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  • 1. Abbasi, R.
    et al.
    Abdou, Y.
    Abu-Zayyad, T.
    Ackermann, M.
    Adams, J.
    Aguilar, J. A.
    Ahlers, M.
    Allen, M. M.
    Altmann, D.
    Andeen, K.
    Auffenberg, J.
    Bai, X.
    Baker, M.
    Barwick, S. W.
    Baum, V.
    Bay, R.
    Alba, J. L. Bazo
    Beattie, K.
    Beatty, J. J.
    Bechet, S.
    Becker, J. K.
    Becker, K. -H
    Benabderrahmane, M. L.
    BenZvi, S.
    Berdermann, J.
    Berghaus, P.
    Berley, D.
    Bernardini, E.
    Bertrand, D.
    Besson, D. Z.
    Bindig, D.
    Bissok, M.
    Blaufuss, E.
    Blumenthal, J.
    Boersma, D. J.
    Bohm, C.
    Bose, D.
    Boeser, S.
    Botner, Olga
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brown, A. M.
    Buitink, S.
    Caballero-Mora, K. S.
    Carson, M.
    Chirkin, D.
    Christy, B.
    Clevermann, F.
    Cohen, S.
    Colnard, C.
    Cowen, D. F.
    Silva, A. H. Cruz
    D'Agostino, M. V.
    Danninger, M.
    Daughhetee, J.
    Davis, J. C.
    De Clercq, C.
    Degner, T.
    Demiroers, L.
    Descamps, F.
    Desiati, P.
    de Vries-Uiterweerd, G.
    DeYoung, T.
    Diaz-Velez, J. C.
    Dierckxsens, M.
    Dreyer, J.
    Dumm, J. P.
    Dunkman, M.
    Eisch, J.
    Ellsworth, R. W.
    Engdegård, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Euler, S.
    Evenson, P. A.
    Fadiran, O.
    Fazely, A. R.
    Fedynitch, A.
    Feintzeig, J.
    Feusels, T.
    Filimonov, K.
    Finley, C.
    Fischer-Wasels, T.
    Fox, B. D.
    Franckowiak, A.
    Franke, R.
    Gaisser, T. K.
    Gallagher, J.
    Gerhardt, L.
    Gladstone, L.
    Gluesenkamp, T.
    Goldschmidt, A.
    Goodman, J. A.
    Gora, D.
    Grant, D.
    Griesel, T.
    Gross, A.
    Grullon, S.
    Gurtner, M.
    Ha, C.
    Ismail, A. Haj
    Hallgren, Allan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Halzen, F.
    Han, K.
    Hanson, K.
    Heinen, D.
    Helbing, K.
    Hellauer, R.
    Hickford, S.
    Hill, G. C.
    Hoffman, K. D.
    Hoffmann, B.
    Homeier, A.
    Hoshina, K.
    Huelsnitz, W.
    Huelss, J. -P
    Hulth, P. O.
    Hultqvist, K.
    Hussain, S.
    Ishihara, A.
    Jakobi, E.
    Jacobsen, J.
    Japaridze, G. S.
    Johansson, H.
    Kampert, K. -H
    Kappes, A.
    Karg, T.
    Karle, A.
    Kenny, P.
    Kiryluk, J.
    Kislat, F.
    Klein, S. R.
    Koehne, H.
    Kohnen, G.
    Kolanoski, H.
    Koepke, L.
    Kopper, S.
    Koskinen, D. J.
    Kowalski, M.
    Kowarik, T.
    Krasberg, M.
    Kroll, G.
    Kurahashi, N.
    Kuwabara, T.
    Labare, M.
    Laihem, K.
    Landsman, H.
    Larson, M. J.
    Lauer, R.
    Luenemann, J.
    Madsen, J.
    Marotta, A.
    Maruyama, R.
    Mase, K.
    Matis, H. S.
    Meagher, K.
    Merck, M.
    Meszaros, P.
    Meures, T.
    Miarecki, S.
    Middell, E.
    Milke, N.
    Miller, J
    Montaruli, T.
    Morse, R.
    Movit, S. M.
    Nahnhauer, R.
    Nam, J. W.
    Naumann, U.
    Nygren, D. R.
    Odrowski, S.
    Olivas, A.
    Olivo, Martino
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    O'Murchadha, A.
    Panknin, S.
    Paul, L.
    Pérez de los Heros, Carlos
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Petrovic, J.
    Piegsa, A.
    Pieloth, D.
    Porrata, R.
    Posselt, J.
    Price, P. B.
    Przybylski, G. T.
    Rawlins, K.
    Redl, P.
    Resconi, E.
    Rhode, W.
    Ribordy, M.
    Richard, A. S.
    Richman, M.
    Rodrigues, J. P.
    Rothmaier, F.
    Rott, C.
    Ruhe, T.
    Rutledge, D.
    Ruzybayev, B.
    Ryckbosch, D.
    Sander, H. -G
    Santander, M.
    Sarkar, S.
    Schatto, K.
    Schmidt, T.
    Schoenwald, A.
    Schukraft, A.
    Schulte, L.
    Schultes, A.
    Schulz, O.
    Schunck, M.
    Seckel, D.
    Semburg, B.
    Seo, S. H.
    Sestayo, Y.
    Seunarine, S.
    Silvestri, A.
    Singh, K.
    Slipak, A.
    Spiczak, G. M.
    Spiering, C.
    Stamatikos, M.
    Stanev, T.
    Stezelberger, T.
    Stokstad, R. G.
    Stoessl, A.
    Strahler, E. A.
    Ström, Rickard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Stueer, M.
    Sullivan, G. W.
    Swillens, Q.
    Taavola, Henric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Taboada, I.
    Tamburro, A.
    Tepe, A.
    Ter-Antonyan, S.
    Tilav, S.
    Toale, P. A.
    Toscano, S.
    Tosi, D.
    van Eijndhoven, N.
    Vandenbroucke, J.
    Van Overloop, A.
    van Santen, J.
    Vehring, M.
    Voge, M.
    Walck, C.
    Waldenmaier, T.
    Wallraff, M.
    Walter, M.
    Weaver, Ch.
    Wendt, C.
    Westerhoff, S.
    Whitehorn, N.
    Wiebe, K.
    Wiebusch, C. H.
    Williams, D. R.
    Wischnewski, R.
    Wissing, H.
    Wolf, M.
    Wood, T. R.
    Woschnagg, K.
    Xu, C.
    Xu, D. L.
    Xu, X. W.
    Yanez, J. P.
    Yodh, G.
    Yoshida, S.
    Zarzhitsky, P.
    Zoll, M.
    IceCube sensitivity for low-energy neutrinos from nearby supernovae2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 535, A109- p.Article in journal (Refereed)
    Abstract [en]

    This paper describes the response of the IceCube neutrino telescope located at the geographic south pole to outbursts of MeV neutrinos from the core collapse of nearby massive stars. IceCube was completed in December 2010 forming a lattice of 5160 photomultiplier tubes that monitor a volume of similar to 1 km(3) in the deep Antarctic ice for particle induced photons. The telescope was designed to detect neutrinos with energies greater than 100 GeV. Owing to subfreezing ice temperatures, the photomultiplier dark noise rates are particularly low. Hence IceCube can also detect large numbers of MeV neutrinos by observing a collective rise in all photomultiplier rates on top of the dark noise. With 2 ms timing resolution, IceCube can detect subtle features in the temporal development of the supernova neutrino burst. For a supernova at the galactic center, its sensitivity matches that of a background-free megaton-scale supernova search experiment. The sensitivity decreases to 20 standard deviations at the galactic edge (30 kpc) and 6 standard deviations at the Large Magellanic Cloud (50 kpc). IceCube is sending triggers from potential supernovae to the Supernova Early Warning System. The sensitivity to neutrino properties such as the neutrino hierarchy is discussed, as well as the possibility to detect the neutronization burst, a short outbreak of nu(e)'s released by electron capture on protons soon after collapse. Tantalizing signatures, such as the formation of a quark star or a black hole as well as the characteristics of shock waves, are investigated to illustrate IceCube's capability for supernova detection.

  • 2. Abbasi, R.
    et al.
    Abdou, Y.
    Abu-Zayyad, T.
    Ackermann, M.
    Adams, J.
    Aguilar, J. A.
    Ahlers, M.
    Allen, M. M.
    Altmann, D.
    Andeen, K.
    Auffenberg, J.
    Bai, X.
    Baker, M.
    Barwick, S. W.
    Bay, R.
    Alba, J. L. Bazo
    Beattie, K.
    Beatty, J. J.
    Bechet, S.
    Becker, J. K.
    Becker, K. -H
    Benabderrahmane, M. L.
    BenZvi, S.
    Berdermann, J.
    Berghaus, P.
    Berley, D.
    Bernardini, E.
    Bertrand, D.
    Besson, D. Z.
    Bindig, D.
    Bissok, M.
    Blaufuss, E.
    Blumenthal, J.
    Boersma, D. J.
    Bohm, C.
    Bose, D.
    Boeser, S.
    Botner, Olga
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brown, A. M.
    Buitink, S.
    Caballero-Mora, K. S.
    Carson, M.
    Chirkin, D.
    Christy, B.
    Clevermann, F.
    Cohen, S.
    Colnard, C.
    Cowen, D. F.
    Silva, A. H. Cruz
    D'Agostino, M. V.
    Danninger, M.
    Daughhetee, J.
    Davis, J. C.
    De Clercq, C.
    Degner, T.
    Demiroers, L.
    Descamps, F.
    Desiati, P.
    de Vries-Uiterweerd, G.
    DeYoung, T.
    Diaz-Velez, J. C.
    Dierckxsens, M.
    Dreyer, J.
    Dumm, J. P.
    Dunkman, M.
    Eisch, J.
    Ellsworth, R. W.
    Engdegård, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Euler, S.
    Evenson, P. A.
    Fadiran, O.
    Fazely, A. R.
    Fedynitch, A.
    Feintzeig, J.
    Feusels, T.
    Filimonov, K.
    Finley, C.
    Fischer-Wasels, T.
    Fox, B. D.
    Franckowiak, A.
    Franke, R.
    Gaisser, T. K.
    Gallagher, J.
    Gerhardt, L.
    Gladstone, L.
    Gluesenkamp, T.
    Goldschmidt, A.
    Goodman, J. A.
    Gora, D.
    Grant, D.
    Griesel, T.
    Gross, A.
    Grullon, S.
    Gurtner, M.
    Ha, C.
    Ismail, A. Haj
    Hallgren, Allan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Halzen, F.
    Han, K.
    Hanson, K.
    Heinen, D.
    Helbing, K.
    Hellauer, R.
    Herquet, P.
    Hickford, S.
    Hill, G. C.
    Hoffman, K. D.
    Hoffmann, B.
    Homeier, A.
    Hoshina, K.
    Huelsnitz, W.
    Huelss, J. -P
    Hulth, P. O.
    Hultqvist, K.
    Hussain, S.
    Ishihara, A.
    Jacobi, E.
    Jacobsen, J.
    Japaridze, G. S.
    Johansson, H.
    Kampert, K. -H
    Kappes, A.
    Karg, T.
    Karle, A.
    Kenny, P.
    Kiryluk, J.
    Kislat, F.
    Klein, S. R.
    Koehne, J. -H
    Kohnen, G.
    Kolanoski, H.
    Koepke, L.
    Kopper, S.
    Koskinen, D. J.
    Kowalski, M.
    Kowarik, T.
    Krasberg, M.
    Kroll, G.
    Kurahashi, N.
    Kuwabara, T.
    Labare, M.
    Laihem, K.
    Landsman, H.
    Larson, M. J.
    Lauer, R.
    Luenemann, J.
    Madsen, J.
    Marotta, A.
    Maruyama, R.
    Mase, K.
    Matis, H. S.
    Meagher, K.
    Merck, M.
    Meszaros, P.
    Meures, T.
    Miarecki, S.
    Middell, E.
    Milke, N.
    Miller, J.
    Montaruli, T.
    Morse, R.
    Movit, S. M.
    Nahnhauer, R.
    Nam, J. W.
    Naumann, U.
    Nygren, D. R.
    Odrowski, S.
    Olivas, A.
    Olivo, M.
    O'Murchadha, A.
    Panknin, S.
    Paul, L.
    Pérez de los Heros, Carlos
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Petrovic, J.
    Piegsa, A.
    Pieloth, D.
    Porrata, R.
    Posselt, J.
    Price, P. B.
    Przybylski, G. T.
    Rawlins, K.
    Redl, P.
    Resconi, E.
    Rhode, W.
    Ribordy, M.
    Richman, M.
    Rodrigues, J. P.
    Rothmaier, F.
    Rott, C.
    Ruhe, T.
    Rutledge, D.
    Ruzybayev, B.
    Ryckbosch, D.
    Sander, H. -G
    Santander, M.
    Sarkar, S.
    Schatto, K.
    Schmidt, T.
    Schoenwald, A.
    Schukraft, A.
    Schultes, A.
    Schulz, O.
    Schunck, M.
    Seckel, D.
    Semburg, B.
    Seo, S. H.
    Sestayo, Y.
    Seunarine, S.
    Silvestri, A.
    Spiczak, G. M.
    Spiering, C.
    Stamatikos, M.
    Stanev, T.
    Stezelberger, T.
    Stokstad, R. G.
    Stoessl, A.
    Strahler, E. A.
    Ström, Rickard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Stueer, M.
    Sullivan, G. W.
    Swillens, Q.
    Taavola, Henric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Taboada, I.
    Tamburro, A.
    Ter-Antonyan, S.
    Tilav, S.
    Toale, P. A.
    Toscano, S.
    Tosi, D.
    van Eijndhoven, N.
    Vandenbroucke, J.
    Van Overloop, A.
    van Santen, J.
    Vehring, M.
    Voge, M.
    Walck, C.
    Waldenmaier, T.
    Wallraff, M.
    Walter, M.
    Weaver, Ch.
    Wendt, C.
    Westerhoff, S.
    Whitehorn, N.
    Wiebe, K.
    Wiebusch, C. H.
    Williams, D. R.
    Wischnewski, R.
    Wissing, H.
    Wolf, M.
    Wood, T. R.
    Woschnagg, K.
    Xu, C.
    Xu, D. L.
    Xu, X. W.
    Yanez, J. P.
    Yodh, G.
    Yoshida, S.
    Zarzhitsky, P.
    Zoll, M.
    Akerlof, C. W.
    Pandey, S. B.
    Yuan, F.
    Zheng, W.
    Searching for soft relativistic jets in core-collapse supernovae with the IceCube optical follow-up program2012In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 539, A60- p.Article in journal (Refereed)
    Abstract [en]

    Context. Transient neutrino sources such as gamma-ray bursts (GRBs) and supernovae (SNe) are hypothesized to emit bursts of high-energy neutrinos on a time-scale of less than or similar to 100 s. While GRB neutrinos would be produced in high relativistic jets, core-collapse SNe might host soft-relativistic jets, which become stalled in the outer layers of the progenitor star leading to an efficient production of high-energy neutrinos. Aims. To increase the sensitivity to these neutrinos and identify their sources, a low-threshold optical follow-up program for neutrino multiplets detected with the IceCube observatory has been implemented. Methods. If a neutrino multiplet, i.e. two or more neutrinos from the same direction within 100 s, is found by IceCube a trigger is sent to the Robotic Optical Transient Search Experiment, ROTSE. The 4 ROTSE telescopes immediately start an observation program of the corresponding region of the sky in order to detect an optical counterpart to the neutrino events. Results. No statistically significant excess in the rate of neutrino multiplets has been observed and furthermore no coincidence with an optical counterpart was found. Conclusions. The search allows, for the first time, to set stringent limits on current models predicting a high-energy neutrino flux from soft relativistic hadronic jets in core-collapse SNe. We conclude that a sub-population of SNe with typical Lorentz boost factor and jet energy of 10 and 3 x 1051 erg, respectively, does not exceed 4.2% at 90% confidence.

  • 3. Abbasi, R.
    et al.
    Abdou, Y.
    Abu-Zayyad, T.
    Adams, J.
    Aguilar, J. A.
    Ahlers, M.
    Andeen, K.
    Auffenberg, J.
    Bai, X.
    Baker, M.
    Barwick, S. W.
    Bay, R.
    Alba, J. L. Bazo
    Beattie, K.
    Beatty, J. J.
    Bechet, S.
    Becker, J. K.
    Becker, K. -H
    Benabderrahmane, M. L.
    BenZvi, S.
    Berdermann, J.
    Berghaus, P.
    Berley, D.
    Bernardini, E.
    Bertrand, D.
    Besson, D. Z.
    Bissok, M.
    Blaufuss, E.
    Blumenthal, J.
    Boersma, D. J.
    Bohm, C.
    Bose, D.
    Boeser, S.
    Botner, Olga
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Braun, J.
    Buitink, S.
    Carson, M.
    Chirkin, D.
    Christy, B.
    Clem, J.
    Clevermann, F.
    Cohen, S.
    Colnard, C.
    Cowen, D. F.
    D'Agostino, M. V.
    Danninger, M.
    Davis, J. C.
    De Clercq, C.
    Demiroers, L.
    Depaepe, O.
    Descamps, F.
    Desiati, P.
    de Vries-Uiterweerd, G.
    DeYoung, T.
    Diaz-Velez, J. C.
    Dierckxsens, M.
    Dreyer, J.
    Dumm, J. P.
    Duvoort, M. R.
    Ehrlich, R.
    Eisch, J.
    Ellsworth, R. W.
    Engdegård, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Euler, S.
    Evenson, P. A.
    Fadiran, O.
    Fazely, A. R.
    Fedynitch, A.
    Feusels, T.
    Filimonov, K.
    Finley, C.
    Foerster, M. M.
    Fox, B. D.
    Franckowiak, A.
    Franke, R.
    Gaisser, T. K.
    Gallagher, J.
    Geisler, M.
    Gerhardt, L.
    Gladstone, L.
    Gluesenkamp, T.
    Goldschmidt, A.
    Goodman, J. A.
    Grant, D.
    Griesel, T.
    Gross, A.
    Grullon, S.
    Gurtner, M.
    Ha, C.
    Hallgren, Allan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Halzen, F.
    Han, K.
    Hanson, K.
    Helbing, K.
    Herquet, P.
    Hickford, S.
    Hill, G. C.
    Hoffman, K. D.
    Homeier, A.
    Hoshina, K.
    Hubert, D.
    Huelsnitz, W.
    Huelss, J. -P
    Hulth, P. O.
    Hultqvist, K.
    Hussain, S.
    Ishihara, A.
    Jacobsen, J.
    Japaridze, G. S.
    Johansson, H.
    Joseph, J. M.
    Kampert, K. H.
    Kappes, A.
    Karg, T.
    Karle, A.
    Kelley, J. L.
    Kemming, N.
    Kenny, P.
    Kiryluk, J.
    Kislat, F.
    Klein, S. R.
    Koehne, J. -H
    Kohnen, G.
    Kolanoski, H.
    Koepke, L.
    Koskinen, D. J.
    Kowalski, M.
    Kowarik, T.
    Krasberg, M.
    Krings, T.
    Kroll, G.
    Kuehn, K.
    Kuwabara, T.
    Labare, M.
    Lafebre, S.
    Laihem, K.
    Landsman, H.
    Larson, M. J.
    Lauer, R.
    Lehmann, R.
    Luenemann, J.
    Madsen, J.
    Majumdar, P.
    Marotta, A.
    Maruyama, R.
    Mase, K.
    Matis, H. S.
    Matusik, M.
    Meagher, K.
    Merck, M.
    Meszaros, P.
    Meures, T.
    Middell, E.
    Milke, N.
    Miller, Jonathan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Montaruli, T.
    Morse, R.
    Movit, S. M.
    Nahnhauer, R.
    Nam, J. W.
    Naumann, U.
    Niessen, P.
    Nygren, D. R.
    Odrowski, S.
    Olivas, A.
    Olivo, M.
    O'Murchadha, A.
    Ono, M.
    Panknin, S.
    Paul, L.
    de los Heros, Carlos Perez
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Petrovic, J.
    Piegsa, A.
    Pieloth, D.
    Porrata, R.
    Posselt, J.
    Price, P. B.
    Prikockis, M.
    Przybylski, G. T.
    Rawlins, K.
    Redl, P.
    Resconi, E.
    Rhode, W.
    Ribordy, M.
    Rizzo, A.
    Rodrigues, J. P.
    Roth, P.
    Rothmaier, F.
    Rott, C.
    Ruhe, T.
    Rutledge, D.
    Ruzybayev, B.
    Ryckbosch, D.
    Sander, H. -G
    Santander, M.
    Sarkar, S.
    Schatto, K.
    Schlenstedt, S.
    Schmidt, T.
    Schukraft, A.
    Schultes, A.
    Schulz, O.
    Schunck, M.
    Seckel, D.
    Semburg, B.
    Seo, S. H.
    Sestayo, Y.
    Seunarine, S.
    Silvestri, A.
    Singh, K.
    Slipak, A.
    Spiczak, G. M.
    Spiering, C.
    Stamatikos, M.
    Stanev, T.
    Stephens, G.
    Stezelberger, T.
    Stokstad, R. G.
    Stoyanov, S.
    Strahler, E. A.
    Straszheim, T.
    Sullivan, G. W.
    Swillens, Q.
    Taavola, Henric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Taboada, I.
    Tamburro, A.
    Tarasova, O.
    Tepe, A.
    Ter-Antonyan, S.
    Tilav, S.
    Toale, P. A.
    Toscano, S.
    Tosi, D.
    Turcan, D.
    van Eijndhoven, N.
    Vandenbroucke, J.
    Van Overloop, A.
    van Santen, J.
    Voge, M.
    Voigt, B.
    Walck, C.
    Waldenmaier, T.
    Wallraff, M.
    Walter, M.
    Weaver, Ch.
    Wendt, C.
    Westerhoff, S.
    Whitehorn, N.
    Wiebe, K.
    Wiebusch, C. H.
    Wikstroem, G.
    Williams, D. R.
    Wischnewski, R.
    Wissing, H.
    Wolf, M.
    Woschnagg, K.
    Xu, C.
    Xu, X. W.
    Yodh, G.
    Yoshida, S.
    Zarzhitsky, P.
    Constraints on high-energy neutrino emission from SN 2008D2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 527, no 4, A28- p.Article in journal (Refereed)
    Abstract [en]

    SN 2008D, a core collapse supernova at a distance of 27 Mpc, was serendipitously discovered by the Swift satellite through an associated X-ray flash. Core collapse supernovae have been observed in association with long gamma-ray bursts and X-ray flashes and a physical connection is widely assumed. This connection could imply that some core collapse supernovae possess mildly relativistic jets in which high-energy neutrinos are produced through proton-proton collisions. The predicted neutrino spectra would be detectable by Cherenkov neutrino detectors like IceCube. A search for a neutrino signal in temporal and spatial correlation with the observed X-ray flash of SN 2008D was conducted using data taken in 2007-2008 with 22 strings of the IceCube detector. Events were selected based on a boosted decision tree classifier trained with simulated signal and experimental background data. The classifier was optimized to the position and a "soft jet" neutrino spectrum assumed for SN 2008D. Using three search windows placed around the X-ray peak, emission time scales from 100-10 000 s were probed. No events passing the cuts were observed in agreement with the signal expectation of 0.13 events. Upper limits on the muon neutrino flux from core collapse supernovae were derived for different emission time scales and the principal model parameters were constrained. While no meaningful limits can be given in the case of an isotropic neutrino emission, the parameter space for a jetted emission can be constrained. Future analyses with the full 86 string IceCube detector could detect up to similar to 100 events for a core-collapse supernova at 10 Mpc according to the soft jet model.

  • 4. Abia, C.
    et al.
    de laverny, P.
    Wahlin, Rurik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Astronomy and Space Physics.
    Chemical analysis of carbon stars in the Local Group2008In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 481, no 1, 161-168 p.Article in journal (Refereed)
    Abstract [en]

    Aims. We present new results of our ongoing chemical study of carbon stars in Local Group galaxies to test the critical dependence of s-process nucleosynthesis on the stellar metallicity. Methods. We collected optical spectra with the VLT/UVES instrument of two carbon stars found in the Carina Dwarf Spheroidal (dSph) galaxy, namely ALW-C6 and ALW-C7. We performed a full chemical analysis using the new generation of hydrostatic, spherically symmetric carbon-rich model atmospheres and the spectral synthesis method in LTE. Results. The luminosities, atmosphere parameters and chemical composition of ALW-C6 and ALW-C7 are compatible with these stars being in the TP-AGB phase undergoing third dredge-up episodes, although their extrinsic nature ( external pollution in a binary stellar system) cannot be definitively excluded. Our chemical analysis shows that the metallicity of both stars agree with the average metallicity ([Fe/H] similar to -1.8 dex) previously derived for this satellite galaxy from the analysis of both low resolution spectra of RGB stars and the observed colour magnitude diagrams. ALW-C6 and ALW-C7 present strong s-element enhancements, [s/Fe] = + 1.6, + 1.5, respectively. These enhancements and the derived s-process indexes [ls/Fe], [hs/Fe] and [hs/ls] are compatible with theoretical s-process nucleosynthesis predictions in low mass AGB stars (similar to 1.5 M(circle dot)) on the basis that the (13)C(alpha, n) (16)O is the main source of neutrons. Furthermore, the analysis of C(2) and CN bands reveals a large carbon enhancement (C/O similar to 7 and 5, respectively), much larger than the values typically found in galactic AGB carbon stars ( C/O similar to 1-2). This is also in agreement with the theoretical prediction that AGB carbon stars are formed more easily through third dredge-up episodes as the initial stellar metallicity drops. However, theoretical low-mass AGB models apparently fail to simultaneously fit the observed s-element and carbon enhancements. On the other hand, Zr is found to be less enhanced in ALW-C7 compared to the other elements belonging to the same s-peak. Although the abundance errors are large, the fact that in this star the abundance of Ti ( which has a similar condensation temperature to Zr) seems also to be lower than those of others metals, may indicate the existence of some depletion into dust-grains in its photosphere.

  • 5. Adén, D.
    et al.
    Eriksson, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Feltzing, S.
    Grebel, E. K.
    Koch, A.
    Wilkinson, M. I.
    An abundance study of red-giant-branch stars in the Hercules dwarf spheroidal galaxy2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 525, A153- p.Article in journal (Refereed)
    Abstract [en]

    Context. Dwarf spheroidal galaxies are some of the most metal-poor, and least luminous objects known. Detailed elemental abundance analysis of stars in these faint objects is key to our understanding of star formation and chemical enrichment in the early universe, and may provide useful information on how larger galaxies form. Aims. Our aim is to provide a determination of [Fe/H] and [Ca/H] for confirmed red-giant branch member stars of the Hercules dwarf spheroidal galaxy. Based on this we explore the ages of the prevailing stellar populations in Hercules, and the enrichment history from supernovae. Additionally, we aim to provide a new simple metallicity calibration for Stromgren photometry for metal-poor, red giant branch stars. Methods. High-resolution, multi-fibre spectroscopy and Stromgren photometry are combined to provide as much information on the stars as possible. From this we derive abundances by solving the radiative transfer equations through marcs model atmospheres. Results. We find that the red-giant branch stars of the Hercules dSph galaxy are more metal-poor than estimated in our previous study that was based on photometry alone. From this, we derive a new metallicity calibration for the Stromgren photometry. Additionally, we find an abundance trend such that [Ca/Fe] is higher for more metal-poor stars, and lower for more metal-rich stars, with a spread of about 0.8 dex. The [Ca/Fe] trend suggests an early rapid chemical enrichment through supernovae of type II, followed by a phase of slow star formation dominated by enrichment through supernovae of type Ia. A comparison with isochrones indicates that the red giants in Hercules are older than 10 Gyr.

  • 6. Alecian, E.
    et al.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Neiner, C.
    Wade, G. A.
    de Batz, B.
    Henrichs, H.
    Grunhut, J. H.
    Bouret, J. -C
    Briquet, M.
    Gagne, M.
    Naze, Y.
    Oksala, M. E.
    Rivinius, T.
    Townsend, R. H. D.
    Walborn, N. R.
    Weiss, W.
    First HARPSpol discoveries of magnetic fields in massive stars2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 536, L6- p.Article in journal (Refereed)
    Abstract [en]

    In the framework of the Magnetism in Massive Stars (MiMeS) project, a HARPSpol Large Program at the 3.6m-ESO telescope has recently started to collect high-resolution spectropolarimetric data of a large number of Southern massive OB stars in the field of the Galaxy and in many young clusters and associations. We report on the first discoveries of magnetic fields in two massive stars with HARPSpol - HD 130807 and HD 122451, and confirm the presence of a magnetic field at the surface of HD 105382 that was previously observed with a low spectral resolution device. The longitudinal magnetic field measurements strongly vary for HD 130807 from similar to-100 G to similar to 700 G. Those of HD 122451 and HD 105382 are less variable with values ranging from similar to-40 to -80 G, and from similar to-300 to -600 G, respectively. The discovery and confirmation of three new magnetic massive stars, including at least two He-weak stars, is an important contribution to one of MiMeS objectives: the understanding of the origin of magnetic fields in massive stars and their impact on stellar structure and evolution.

  • 7. Alecian, E.
    et al.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Petit, V.
    Grunhut, J.
    Landstreet, J.
    Oksala, M. E.
    Wade, G. A.
    Hussain, G.
    Neiner, C.
    Bohlender, D.
    Discovery of new magnetic early-B stars within the MiMeS HARPSpol survey2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 567, A28- p.Article in journal (Refereed)
    Abstract [en]

    Context. The Magnetism in Massive Stars (MiMeS) project aims at understanding the origin of the magnetic fields in massive stars as well as their impact on stellar internal structure, evolution, and circumstellar environment. Aims. One of the objectives of the MiMeS project is to provide stringent observational constraints on the magnetic fields of massive stars; however, identification of magnetic massive stars is challenging, as only a few percent of high-mass stars host strong fields detectable with the current instrumentation. Hence, one of the first objectives of the MiMeS project was to search for magnetic objects among a large sample of massive stars, and to build a sub-sample for in-depth follow-up studies required to test the models and theories of fossil field origins, magnetic wind confinement and magnetospheric properties, and magnetic star evolution. Methods. We obtained high-resolution spectropolarimetric observations of a large number of OB stars thanks to three large programs (LP) of observations that have been allocated on the high-resolution spectropolarimeters ESPaDOnS, Narval, and the polarimetric module HARPSpol of the HARPS spectrograph. We report here on the methods and first analysis of the HARPSpol magnetic detections. We identified the magnetic stars using a multi-line analysis technique. Then, when possible, we monitored the new discoveries to derive their rotation periods, which are critical for follow-up and magnetic mapping studies. We also performed a first-look analysis of their spectra and identified obvious spectral anomalies (e. g., surface abundance peculiarities, Ha emission), which are also of interest for future studies. Results. In this paper, we focus on eight of the 11 stars in which we discovered or confirmed a magnetic field from the HARPSpol LP sample (the remaining three were published in a previous paper). Seven of the fields were detected in early-type Bp stars, while the last field was detected in the Ap companion of a normal early B-type star. We report obvious spectral and multiplicity properties, as well as our measurements of their longitudinal field strengths, and their rotation periods when we are able to derive them. We also discuss the presence or absence of Ha emission with respect to the theory of centrifugally-supported magnetospheres.

  • 8. Alecian, E.
    et al.
    Neiner, C.
    Mathis, S.
    Catala, C.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Landstreet, J.
    The dramatic change of the fossil magnetic field of HD 190073: Evidence of the birth of the convective core in a Herbig star?2013In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 549, L8- p.Article in journal (Refereed)
    Abstract [en]

    In the context of the ESPaDOnS and Narval spectropolarimetric surveys of Herbig Ae/Be stars, we discovered and then monitored the magnetic field of HD 190073 over more than four years, from 2004 to 2009. Our observations all displayed similar Zeeman signatures in the Stokes V spectra, indicating that HD 190073 hosted an aligned dipole, stable over many years, consistent with a fossil origin. We obtained new observations of the star in 2011 and 2012 and detected clear variations of the Zeeman signature on timescales of days to weeks, indicating that the configuration of its field has changed between 2009 and 2011. Such a sudden change of external structure of a fossil field has never previously been observed in any intermediate or high-mass star. HD 190073 is an almost entirely radiative pre-main sequence star, probably hosting a growing convective core. We propose that this dramatic change is the result of the interaction between the fossil field and the ignition of a dynamo field generated in the newly-born convective core.

  • 9.
    Alvarado-Gomez, J. D.
    et al.
    European So Observ, D-85748 Garching, Germany.;Univ Munich, Univ Sternwarte Munchen, D-81679 Munich, Germany..
    Hussain, G. A. J.
    European So Observ, D-85748 Garching, Germany.;Univ Toulouse, UPS OMP, Inst Rech Astrophys & Planetol, F-31400 Toulouse, France..
    Grunhut, J.
    European So Observ, D-85748 Garching, Germany..
    Fares, R.
    INAF Osservatorio Astrofis Catania, I-95123 Catania, Italy..
    Donati, J. -F
    Alecian, E.
    UJF Grenoble 1, CNRS, INSU, IPAG,UMR 5274, Grenoble, France.;Univ Paris Diderot, UPMC, CNRS, LESIA,Observ Paris,UMR 8109, F-92190 Meudon, France..
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Oksala, M.
    Univ Paris Diderot, UPMC, CNRS, LESIA,Observ Paris,UMR 8109, F-92190 Meudon, France..
    Morin, J.
    CNRS, UMR 5299, LUPM, F-34095 Montpellier 05, France.;Univ Montpellier, F-34095 Montpellier 05, France..
    Redfield, S.
    Wesleyan Univ, Dept Astron, Van Vleck Observ, Middletown, CT 06459 USA..
    Cohen, O.
    Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA..
    Drake, J. J.
    Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA..
    Jardine, M.
    Univ St Andrews, Sch Phys & Astron, SUPA, St Andrews KY16 9SS, Fife, Scotland..
    Matt, S.
    Univ Exeter, Dept Phys & Astron, Exeter EX4 4SB, Devon, England..
    Petit, P.
    Univ Toulouse, UPS OMP, Inst Rech Astrophys & Planetol, F-31400 Toulouse, France.;CNRS, Inst Rech Astrophys & Planetol, F-31400 Toulouse, France..
    Walter, F. M.
    SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA..
    Activity and magnetic field structure of the Sun-like planet-hosting star HD 12372015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 582, A38Article in journal (Refereed)
    Abstract [en]

    We analyse the magnetic activity characteristics of the planet-hosting Sun-like star, HD 1237, using HARPS spectro-polarimetric time-series data. We find evidence of rotational modulation of the magnetic longitudinal field measurements that is consistent with our ZDI analysis with a period of 7 days. We investigate the effect of customising the LSD mask to the line depths of the observed spectrum and find that it has a minimal effect on the shape of the extracted Stokes V profile but does result in a small increase in the S/N (similar to 7%). We find that using a Milne-Eddington solution to describe the local line profile provides a better fit to the LSD profiles in this slowly rotating star, which also affects the recovered ZDI field distribution. We also introduce a fit-stopping criterion based on the information content (entropy) of the ZDI map solution set. The recovered magnetic field maps show a strong (+90 G) ring-like azimuthal field distribution and a complex radial field dominating at mid latitudes (similar to 45 degrees). Similar magnetic field maps are recovered from data acquired five months apart. Future work will investigate how this surface magnetic field distribution affeccts the coronal magnetic field and extended environment around this planet-hosting star.

  • 10.
    Aronson, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Waldén, P.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Using near-infrared spectroscopy for characterization of transiting exoplanets2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 578, A133Article in journal (Refereed)
    Abstract [en]

    Context. We propose a method for observing transiting exoplanets with near-infrared high-resolution spectrometers. Aims. We aim to create a robust data analysis method for recovering atmospheric transmission spectra from transiting exoplanets over a wide wavelength range in the near-infrared. Methods. By using an inverse method approach, combined with stellar models and telluric transmission spectra, the method recovers the transiting exoplanet's atmospheric transmittance at high precision over a wide wavelength range. We describe our method and have tested it by simulating observations. Results. This method is capable of recovering transmission spectra of high enough accuracy to identify absorption features from molecules such as O-2, CH4, CO2, and H2O. This accuracy is achievable for Jupiter-size exoplanets at S/N that can be reached for 8m class telescopes using high-resolution spectrometers (R > 20 000) during a single transit, and for Earth-size planets and super-Earths transiting late K or M dwarf stars at S/N reachable during observations of less than 10 transits. We also analyse potential error sources to show the robustness of the method. Conclusions. Detection and characterization of atmospheres of both Jupiter-size planets and smaller rocky planets looks promising using this set-up.

  • 11. Arroyo-Torres, B.
    et al.
    Wittkowski, M.
    Chiavassa, A.
    Scholz, M.
    Freytag, Bernd
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Marcaide, J. M.
    Hauschildt, P. H.
    Wood, P. R.
    Abellan, F. J.
    What causes the large extensions of red supergiant atmospheres?: Comparisons of interferometric observations with 1D hydrostatic, 3D convection, and 1D pulsating model atmospheres2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 575, A50Article in journal (Refereed)
    Abstract [en]

    Aims. This research has two main goals. First, we present the atmospheric structure and the fundamental parameters of three red supergiants (RSGs), increasing the sample of RSGs observed by near-infrared spectro-interferometry. Additionally, we test possible mechanisms that may explain the large observed atmospheric extensions of RSGs. Methods. We carried out spectro-interferometric observations of the.RSGs V602 Car, EID 95687, and EID 183589 in the near-infrared K-band (1.92-2.47 mu m) with the VLTI/AMBER instrument at medium spectral resolution (R similar to 1500). To categorize and comprehend the extended atmospheres, we compared our observational results to predictions by available hydrostatic PHOENIX, available 3D convection, and new 1D self-excited pulsation models of RSGs. Results. Our near-infrared flux spectra of V602 Car, HD 95687, and HD 183589 are well reproduced by the PHOENIX model atmospheres. The continuum visibility values are consistent with a limb-darkened disk as predicted by the PHOENIX models, allowing us to determine the angular diameter and the fundamental parameters of our sources. Nonetheless, in the case of V602 Car and HD 95686, the PHOENIX model visibilities do not predict the large observed extensions of molecular layers, most remarkably in the CO bands. Likewise, the 3D convection models and the ID pulsation models with typical parameters of RSGs lead to compact atmospheric structures as well, which are similar to the structure of the hydrostatic PHOENIX models. They can also not explain the observed decreases in the visibilities and thus the large atmospheric molecular extensions. The full sample of our RSGs indicates increasing observed atmospheric extensions with increasing luminosity and decreasing surface gravity, and no correlation with effective temperature or variability amplitude. Conclusions. The location of our RSG sources in the Hertzsprung-Russell diagram is contirm.ed to be consistent with the red limits of recent evolutionary tracks. The observed extensions of the atmospheric layers of our sample of RSGs are comparable to those of Mira stars. This phenomenon is not predicted by any of the considered model atmospheres including as 311) convection and new 1D pulsation models of.RSGs. This confirms that neither convection nor pulsation alone can levitate the molecular atmospheres of.RSGs. Our observed correlation of atmospheric extension with luminosity supports a scenario of radiative acceleration on Doppler-shifted molecular lines.

  • 12. Auger, A. -T
    et al.
    Groussin, O.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Jorda, L.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Bouley, S.
    Univ Paris 11, Lab GEOPS, Geosci Paris Sud, F-91405 Orsay, France.;Inst Mecan Celeste & Calcul Ephemerides, UMR 8028, F-75014 Paris, France..
    Gaskell, R.
    Planetary Sci Inst, Tucson, AZ 85719 USA..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Capanna, C.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Pommerol, A.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Rodrigo, R.
    Ctr Astrobiol INTA CSIC, Madrid 28691, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Keller, H. U.
    Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, CISAS, I-35100 Padua, Italy..
    Cremonese, G.
    Univ Padua, Dept Mech Engn, I-35131 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    Univ Padua, Dept Mech Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, UNITN, I-38100 Trento, Italy..
    El-Maarry, M. R.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Fulle, M.
    Osserv Astron Trieste, INAF, I-34143 Trieste, Italy..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Ip, W. -H
    Knollenberg, J.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kramm, J. -R
    Kuehrt, E.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kueppers, M.
    European Space Astron Ctr ESA, Operat Dept, Madrid 28691, Spain..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Marchi, S.
    Southwest Res Inst, Boulder, CO 80302 USA..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Massironi, M.
    Osserv Astron Padova, INAF, I-35121 Padua, Italy.;Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Michalik, H.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Datentech & Kommunikat Netze, D-38106 Braunschweig, Germany..
    Naletto, G.
    Univ Padua, CISAS, I-35100 Padua, Italy.;CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Pajola, M.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Sabau, L.
    Inst Nacl Tecn Aeroesp, Madrid 28850, Spain..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Wenzel, K. -P
    Geomorphology of the Imhotep region on comet 67P/Churyumov-Gerasimenko from OSIRIS observations2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, A35Article in journal (Refereed)
    Abstract [en]

    Context. Since August 2014, the OSIRIS Narrow Angle Camera (NAC) onboard the Rosetta spacecraft has acquired high spatial resolution images of the nucleus of comet 67P/Churyumov-Gerasimenko, down to the decimeter scale. This paper focuses on the Imhotep region, located on the largest lobe of the nucleus, near the equator. Aims. We map, inventory, and describe the geomorphology of the Imhotep region. We propose and discuss some processes to explain the formation and ongoing evolution of this region. Methods. We used OSIRIS NAC images, gravitational heights and slopes, and digital terrain models to map and measure the morphologies of Imhotep. Results. The Imhotep region presents a wide variety of terrains and morphologies: smooth and rocky terrains, bright areas, linear features, roundish features, and boulders. Gravity processes such as mass wasting and collapse play a significant role in the geomorphological evolution of this region. Cometary processes initiate erosion and are responsible for the formation of degassing conduits that are revealed by elevated roundish features on the surface. We also propose a scenario for the formation and evolution of the Imhotep region; this implies the presence of large primordial voids inside the nucleus, resulting from its formation process.

  • 13. Bagnulo, S.
    et al.
    Fossati, L.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Landstreet, J. D.
    The importance of non-photon noise in stellar spectropolarimetry The spurious detection of a non-existing magnetic field in the AO supergiant HD 922072013In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 559, A103- p.Article in journal (Refereed)
    Abstract [en]

    Context. The low-resolution, Cassegrain mounted, FORS spectropolarimeter of the ESO Very Large Telescope is being extensively used for magnetic field surveys. Some of the new discoveries suggest that relatively strong magnetic fields may play an important role in numerous physical phenomena observed in the atmospheres as well as in the circumstellar environments of certain kinds of stars. Aims. We show in detail how small instabilities or data-reduction inaccuracies represent an alternative explanation for the origin of certain signals of circular polarisation published in recent years. Methods. With the help of analytical calculations we simulate the observation of a spectral line in spectropolarimetric mode, adding very small spurious wavelength shifts, which may mimic the effects of seeing variations, rapid variations of the stellar radial velocity, or instrument instabilities. As a case study, we then re-visit the FORS2 measurements that have been used to claim the discovery of a magnetic field in the A0 supergiant HD 92207. In addition, we present new observations of this star obtained with the HARPSpol instrument. Results. Both calibration and science data show compelling evidence that photon-noise is not the only source of error in magnetic field measurements, especially in sharp spectral lines. Non-photon noise may be kept under control by accurate data reduction and quality controls. Our re-analysis of FORS2 observations of HD 92207 shows no evidence of a magnetic field, and we are able to reproduce the previous FORS detection only by degrading the quality of our wavelength calibration. Our HARPSpol spectropolarimetric measurements show no evidence of a magnetic field at the level of 10 G. Conclusions. Our work contributes to a better understanding of the importance of accurate data treatment and instrument characterisation, and demonstrates that ultra-high signal-to-noise ratio measurements do not automatically translate into ultra-high accuracy.

  • 14. Bagnulo, S.
    et al.
    Landstreet, J. D.
    Fossati, L.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Magnetic field measurements and their uncertainties: the FORS1 legacy2012In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 538, A129- p.Article in journal (Refereed)
    Abstract [en]

    Context. During the last decade, the FORS1 instrument of the ESO Very Large Telescope has been extensively used to study stellar magnetism. A number of interesting discoveries of magnetic fields in several classes of stars have been announced, many of which obtained at a similar to 3 sigma level; some of the discoveries are confirmed by measurements obtained with other instruments, some are not.

    Aims. We investigate the reasons for the discrepancies between the results obtained with FORS1 and those obtained with other instruments.

    Methods. Using the ESO FORS pipeline, we have developed a semi-automatic procedure for magnetic field determination. We have applied this procedure to the full content of circular spectropolarimetric measurements of the FORS1 archive (except for most of the observations obtained in multi-object spectropolarimetric mode). We have devised and applied a number of consistency checks to our field determinations, and we have compared our results to those previously published in the literature.

    Results. We find that for high signal-to-noise ratio measurements, photon noise does not account for the full error bars. We discuss how field measurements depend on the specific algorithm adopted for data reduction, and we show that very small instrument flexures, negligible in most of the instrument applications, may be responsible for some spurious field detections in the null profiles. Finally, we find that we are unable to reproduce some results previously published in the literature. Consequently, we do not confirm some important discoveries of magnetic fields obtained with FORS1 and reported in previous publications.

    Conclusions. Our revised field measurements show that there is no contradiction between the results obtained with the low-resolution spectropolarimeter FORS1 and those obtained with high-resolution spectropolarimeters. FORS1 is an instrument capable of performing reliable magnetic field measurements, provided that the various sources of uncertainties are properly taken into account.

  • 15. Bailer-Jones, C. A. L.
    et al.
    Andrae, R.
    Arcay, B.
    Astraatmadja, T.
    Bellas-Velidis, I.
    Berihuete, A.
    Bijaoui, A.
    Carrion, C.
    Dafonte, C.
    Damerdji, Y.
    Dapergolas, A.
    de Laverny, P.
    Delchambre, L.
    Drazinos, P.
    Drimmel, R.
    Fremat, Y.
    Fustes, D.
    Garcia-Torres, M.
    Guede, C.
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Janotto, A. -M
    Karampelas, A.
    Kim, D. -W
    Knude, J.
    Kolka, I.
    Kontizas, E.
    Kontizas, M.
    Korn, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Lanzafame, A. C.
    Lebreton, Y.
    Lindstrom, H.
    Liu, C.
    Livanou, E.
    Lobel, A.
    Manteiga, M.
    Martayan, C.
    Ordenovic, Ch.
    Pichon, B.
    Recio-Blanco, A.
    Rocca-Volmerange, B.
    Sarro, L. M.
    Smith, K.
    Sordo, R.
    Soubiran, C.
    Surdej, J.
    Thevenin, F.
    Tsalmantza, P.
    Vallenari, A.
    Zorec, J.
    The Gaia astrophysical parameters inference system (Apsis) Pre-launch description2013In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 559, A74- p.Article in journal (Refereed)
    Abstract [en]

    The Gaia satellite will survey the entire celestial sphere down to 20th magnitude, obtaining astrometry, photometry, and low resolution spectrophotometry on one billion astronomical sources, plus radial velocities for over one hundred million stars. Its main objective is to take a census of the stellar content of our Galaxy, with the goal of revealing its formation and evolution. Gaia's unique feature is the measurement of parallaxes and proper motions with hitherto unparalleled accuracy for many objects. As a survey, the physical properties of most of these objects are unknown. Here we describe the data analysis system put together by the Gaia consortium to classify these objects and to infer their astrophysical properties using the satellite's data. This system covers single stars, (unresolved) binary stars, quasars, and galaxies, all covering a wide parameter space. Multiple methods are used for many types of stars, producing multiple results for the end user according to different models and assumptions. Prior to its application to real Gaia data the accuracy of these methods cannot be assessed definitively. But as an example of the current performance, we can attain internal accuracies (rms residuals) on F, G, K, M dwarfs and giants at G = 15 (V = 15-17) for a wide range of metallicites and interstellar extinctions of around 100 K in effective temperature (T-eff), 0.1 mag in extinction (A(0)), 0.2 dex in metallicity ([Fe/H]), and 0.25 dex in surface gravity (log g). The accuracy is a strong function of the parameters themselves, varying by a factor of more than two up or down over this parameter range. After its launch in December 2013, Gaia will nominally observe for five years, during which the system we describe will continue to evolve in light of experience with the real data.

  • 16. Bailey, J. D.
    et al.
    Landstreet, J. D.
    Bagnulo, S.
    Fossati, L.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Paladini, C.
    Silvester, J.
    Wade, G.
    Magnetic field and atmospheric chemical abundances of the magnetic Ap star HD 3181072011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 535, A25- p.Article in journal (Refereed)
    Abstract [en]

    Context. A new generation of powerful and efficient spectropolarimeters has recently been used to provide the first sample of magnetic Ap stars of accurately known ages. Modelling of these data offer the possibility of significant new insights into the physics and main sequence evolution of these remarkable stars.

    Aims. New spectra have been obtained with the ESPaDOnS spectropolarimeter, and are supplemented with unpolarised spectra from the ESO UVES, UVES-FLAMES, and HARPS spectrographs, of the very peculiar large-field magnetic Ap star HD 318107, a member of the open cluster NGC 6405 and thus a star with a well-determined age. The available data provide sufficient material with which to re-analyse the first-order model of the magnetic field geometry and to derive chemical abundances of Si, Ti, Fe, Nd, Pr, Mg, Cr, Mn, O, and Ca.

    Methods. The models were obtained using ZEEMAN, a program which synthesises spectral line profiles for stars that have magnetic fields. The magnetic field structure was modelled with a low-order colinear multipole expansion, using coefficients derived from the observed variations of the field strength with rotation phase. The abundances of several elements were determined using spectral synthesis. After experiments with a very simple model of uniform abundance on each of three rings of equal width in co-latitude and symmetric about the assumed magnetic axis, we decided to model the spectra assuming uniform abundances of each element over the stellar surface.

    Results. The new magnetic field measurements allow us to refine the rotation period of HD 318107 to P = 9.7088 +/- 0.0007 days. Appropriate magnetic field model parameters were found that very coarsely describe the (apparently rather complex) field moment variations. Spectrum synthesis leads to the derivation of mean abundances for the elements Mg, Si, Ca, Ti, Cr, Fe, Nd, and Pr. All of these elements except for Mg and Ca are strongly overabundant compared to the solar abundance ratios. There is considerable evidence of non-uniformity, for example in the different values of < B(z)> found using lines of different elements.

    Conclusions. The present data set, while limited, is nevertheless sufficient to provide a useful first-order assessment of both the magnetic and surface abundance properties of HD 318107, making it one of the very few magnetic Ap stars of well-known age for which both of these properties have been studied.

  • 17.
    Barklem, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Electron-impact excitation of neutral oxygen2007In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 462, no 2, 781-788 p.Article in journal (Refereed)
    Abstract [en]

    Aims.Our goal was to calculate transition rates from ground and excited states in neutral oxygen atoms due to electron collisions for non-LTE modelling of oxygen in late-type stellar atmospheres, thus enabling the reliable interpretation of oxygen lines in stellar spectra.Methods.A 38-state R-matrix calculation in LS-coupling has been performed. Basis orbitals from the literature are adopted, and a large set of configurations are included to obtain good representations of the target wave functions. Rate coefficients are calculated by averaging over a Maxwellian velocity distribution. Results.Estimates for the cross sections and rate coefficients are presented for transitions between the seven lowest LS states of neutral oxygen. The cross sections for excitation from the ground state compare well with existing experimental and recent theoretical results.

  • 18.
    Barklem, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Non-LTE Balmer line formation in late-type spectra: Effects of atomic processes involving hydrogen atoms2007In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 466, no 1, 327-337 p.Article in journal (Refereed)
    Abstract [en]

    Context.The wings of Balmer lines are often used as effective temperature diagnostics for late-type (F, G, K) stars under the assumption they form in local thermodynamic equilibrium (LTE). Aims.Our goal is to investigate the non-LTE excitation and ionisation of hydrogen and the formation of Balmer lines in late-type stellar atmospheres, to establish if the assumption of LTE is justified. Furthermore, we aim to determine which collision processes are important for the problem; in particular, the role of collision processes with hydrogen atoms is investigated.Methods.A model hydrogen atom for non-LTE calculations has been constructed accounting for various collision processes using the best available data from the literature. The processes included are inelastic collisions with electrons and hydrogen atoms, mutual neutralisation and Penning ionisation. Non-LTE calculations are performed using the MULTI code and the MACKKL semi-empirical solar model, and the relative importance of the collision processes is investigated. Similar calculations are performed for MARCS theoretical models of other late-type stellar atmospheres.Results.Our calculations show electron collisions alone are not sufficient to establish LTE for the formation of Balmer line wings. Mutual neutralisation and Penning ionisation are found to be unimportant. The role of inelastic collisions with neutral hydrogen is unclear. The available data for these processes is of questionable quality, and different prescriptions for the rate coefficents give significantly different results for the Balmer line wings. Conclusions.Improved calculations or experimental data are needed for excitation and, particularly, ionisation of hydrogen atoms in low-lying states by hydrogen atom impact at near threshold energies. Until such data are available, the assumption of LTE for the formation of Balmer line wings in late-type stars is questionable.

  • 19.
    Barklem, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Belyaev, A. K.
    Dickinson, A. S.
    Gadea, F. X.
    Inelastic Na+H collision data for non-LTE applications in stellar atmospheres2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 519, A20- p.Article in journal (Refereed)
    Abstract [en]

    Rate coefficients for inelastic Na+H collisions are calculated for all transitions between the ten levels up to and including the ionic state (ion-pair production), namely Na(3s,3p,4s,3d,4p,5s,4d,4f,5p)+H(1s) and Na++H-. The calculations are based on recent full quantum scattering cross-section calculations. The data are needed for non-LTE applications in cool astrophysical environments, especially cool stellar atmospheres, and are presented for a temperature range of 500-8000 K. From consideration of the sensitivity of the cross-sections to input quantum chemical data and the results of different methods for the scattering calculations, a measure of the possible uncertainties in the rate coefficients is estimated.

  • 20.
    Barklem, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Belyaev, A. K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Guitou, M.
    Feautrier, N.
    Gadea, F. X.
    Spielfiedel, A.
    On inelastic hydrogen atom collisions in stellar atmospheres2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 530, A94- p.Article in journal (Refereed)
    Abstract [en]

    The influence of inelastic hydrogen atom collisions on non-LTE spectral line formation has been, and remains to be, a significant source of uncertainty for stellar abundance analyses, due to the difficulty in obtaining accurate data for low-energy atomic collisions either experimentally or theoretically. For lack of a better alternative, the classical "Drawin formula" is often used. Over recent decades, our understanding of these collisions has improved markedly, predominantly through a number of detailed quantum mechanical calculations. In this paper, the Drawin formula is compared with the quantum mechanical calculations both in terms of the underlying physics and the resulting rate coefficients. It is shown that the Drawin formula does not contain the essential physics behind direct excitation by H atom collisions, the important physical mechanism being quantum mechanical in character. Quantitatively, the Drawin formula compares poorly with the results of the available quantum mechanical calculations, usually significantly overestimating the collision rates by amounts that vary markedly between transitions.

  • 21.
    Barklem, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Belyaev, A. K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Spielfiedel, A.
    Guitou, M.
    Feautrier, N.
    Inelastic Mg plus H collision data for non-LTE applications in stellar atmospheres2012In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 541, A80- p.Article in journal (Refereed)
    Abstract [en]

    Rate coefficients for inelastic Mg+H collisions are calculated for all transitions between the lowest seven levels and the ionic state (charge transfer), namely Mg(3s(2) S-1, 3s3p P-3, 3s3p P-1, 3s4s S-3, 3s4s S-1, 3s3d D-1, 3s4p P-3)+H(1s) and Mg+(3s S-2)+H-. The rate coefficients are based on cross-sections from full quantum scattering calculations, which are themselves based on detailed quantum chemical calculations for the MgH molecule. The data are needed for non-LTE applications in cool astrophysical environments, especially cool stellar atmospheres, and are presented for a temperature range of 500-8000 K. From consideration of the sensitivity of the cross-sections to various uncertainties in the calculations, most importantly input quantum chemical data and the numerical accuracy of the scattering calculations, a measure of the possible uncertainties in the rate coefficients is estimated.

  • 22.
    Barklem, Paul S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Collet, R.
    Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia.;Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munkegade 120, DK-8000 Aarhus C, Denmark..
    Partition functions and equilibrium constants for diatomic molecules and atoms of astrophysical interest2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 588, A96Article in journal (Refereed)
    Abstract [en]

    Partition functions and dissociation equilibrium constants are presented for 291 diatomic molecules for temperatures in the range from near absolute zero to 10 000 K, thus providing data for many diatomic molecules of astrophysical interest at low temperature. The calculations are based on molecular spectroscopic data from the book of Huber & Herzberg (1979, Constants of Diatomic Molecules) with significant improvements from the literature, especially updated data for ground states of many of the most important molecules by Irikura (2007, J. Phys. Chem. Ref. Data, 36, 389). Dissociation energies are collated from compilations of experimental and theoretical values. Partition functions for 284 species of atoms for all elements from H to U are also presented based on data collected at NIST. The calculated data are expected to be useful for modelling a range of low density astrophysical environments, especially star-forming regions, protoplanetary disks, the interstellar medium, and planetary and cool stellar atmospheres. The input data, which will be made available electronically, also provides a possible foundation for future improvement by the community.

  • 23.
    Barucci, M. A.
    et al.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Filacchione, G.
    INAF IAPS, I-00133 Rome, Italy..
    Fornasier, S.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France.;Univ Paris Diderot, Sorbonne Paris Cite, 4 Rue Elsa Morante, F-75205 Paris 13, France..
    Raponi, A.
    INAF IAPS, I-00133 Rome, Italy..
    Deshapriya, J. D. P.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Tosi, F.
    INAF IAPS, I-00133 Rome, Italy..
    Feller, C.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France.;Univ Paris Diderot, Sorbonne Paris Cite, 4 Rue Elsa Morante, F-75205 Paris 13, France..
    Ciarniello, M.
    INAF IAPS, I-00133 Rome, Italy..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Capaccioni, F.
    INAF IAPS, I-00133 Rome, Italy..
    Pommerol, A.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Massironi, M.
    Univ Padua, Dipartimento Geosci, I-35122 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Merlin, F.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France.;Univ Paris Diderot, Sorbonne Paris Cite, 4 Rue Elsa Morante, F-75205 Paris 13, France..
    Vincent, J. -B
    Fulchignoni, M.
    Univ Paris Diderot, Sorbonne Paris Cite, 4 Rue Elsa Morante, F-75205 Paris 13, France..
    Guilbert-Lepoutre, A.
    Observ Sci Univers, F-25000 Besancon, France..
    Perna, D.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Capria, M. T.
    INAF IAPS, I-00133 Rome, Italy..
    Hasselmann, P. H.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Rousseau, B.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Bockelee-Morvan, D.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Lamy, P. L.
    Aix Marseille Univ, F-13388 Marseille 13, France..
    De Sanctis, C.
    INAF IAPS, I-00133 Rome, Italy..
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.;Univ Bern, Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Erard, S.
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Leyrat, C.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Drossart, P.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Keller, H. U.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Arnold, G.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Bertaux, J. -L
    Bertini, I.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Cerroni, P.
    INAF IAPS, I-00133 Rome, Italy..
    Cremonese, G.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6, I-35131 Padua, Italy..
    Davidsson, B. J. R.
    JPL, 4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    El-Maarry, M. R.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Fonti, S.
    Univ Salento, Dipartimento Fis, Lecce, LE, Italy..
    Fulle, M.
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34143 Trieste, Italy..
    Groussin, O.
    CNRS, Lab Astrophys Marseille, UMR 7326, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W.
    Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan..
    Jorda, L.
    CNRS, Lab Astrophys Marseille, UMR 7326, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Kappel, D.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Knollenberg, J.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kramm, J. -R
    Kuehrt, E.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, M.
    ESA ESAC, POB 78, Villanueva De La Canada 28691, Spain..
    Lara, L.
    CSIC, Inst Astrofis Andalucia, Granada 18080, Spain..
    Lazzarin, M.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Moreno, J. J. Lopez
    CSIC, Inst Astrofis Andalucia, Granada 18080, Spain..
    Mancarella, F.
    Univ Salento, Dipartimento Fis, Lecce, LE, Italy..
    Marzari, F.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Mottola, S.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Naletto, G.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6, I-35131 Padua, Italy..
    Pajola, M.
    NASA, Ames Res Ctr, Moffett Field, CA 94035 USA..
    Palomba, E.
    INAF IAPS, I-00133 Rome, Italy..
    Quirico, E.
    UJF Grenoble 1, CNRS INSU, F-38400 St Martin Dheres, France..
    Schmitt, B.
    UJF Grenoble 1, CNRS INSU, F-38400 St Martin Dheres, France..
    Thomas, N.
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Detection of exposed H2O ice on the nucleus of comet 67P/Churyumov-Gerasimenko as observed by Rosetta OSIRIS and VIRTIS instruments2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 595, A102Article in journal (Refereed)
    Abstract [en]

    Context. Since the orbital insertion of the Rosetta spacecraft, comet 67P/Churyumov-Gerasimenko (67P) has been mapped by OSIRIS camera and VIRTIS spectro-imager, producing a huge quantity of images and spectra of the comet's nucleus. Aims. The aim of this work is to search for the presence of H2O on the nucleus which, in general, appears very dark and rich in dehydrated organic material. After selecting images of the bright spots which could be good candidates to search for H2O ice, taken at high resolution by OSIRIS, we check for spectral cubes of the selected coordinates to identify these spots observed by VIRTIS. Methods. The selected OSIRIS images were processed with the OSIRIS standard pipeline and corrected for the illumination conditions for each pixel using the Lommel-Seeliger disk law. The spots with higher I/F were selected and then analysed spectrophotometrically and compared with the surrounding area. We selected 13 spots as good targets to be analysed by VIRTIS to search for the 2 mu m absorption band of water ice in the VIRTIS spectral cubes. Results. Out of the 13 selected bright spots, eight of them present positive H2O ice detection on the VIRTIS data. A spectral analysis was performed and the approximate temperature of each spot was computed. The H2O ice content was confirmed by modeling the spectra with mixing (areal and intimate) of H2O ice and dark terrain, using Hapke's radiative transfer modeling. We also present a detailed analysis of the detected spots.

  • 24.
    Belyaev, Andrey K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Inelastic aluminium-hydrogen collision data for non-LTE applications in stellar atmospheres2013In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 560, A60- p.Article in journal (Refereed)
    Abstract [en]

    Aims. Rate coefficients for inelastic Al + H and Al+ + H- collisions are calculated for all transitions between the seven low-lying levels up to and including the ionic state, namely Al(3p, 4s, 3d, 4p, 5s, nd)+H(1s) and Al+ + H-. The data are needed for non-LTE applications in stellar atmospheres and are presented for a temperature range of 1000-10 000 K.

    Methods. The calculations were obtained by means of the recently proposed model approach based on the asymptotic method for electronic molecular structure determination and on the branching probability current method for the nonadiabatic nuclear dynamics.

    Results. It is shown that the processes with the highest rates are the excitation and de-excitation ones between the Al(3d), Al(4p) and Al(4s) states in collisions with H, as well as the ion-pair formation and the mutual neutralization processes between these states and the ionic state.

  • 25.
    Belyaev, Andrey K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Yakovleva, Svetlana A.
    Barklem, Paul S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Inelastic silicon-hydrogen collision data for non-LTE applications in stellar atmospheres2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 572, A103- p.Article in journal (Refereed)
    Abstract [en]

    Aims. Inelastic processes in low-energy Si + H and Si+ + H- collisions are treated for the states from the ground state up to the ionic state, in order to provide rate coefficients needed for non-LTE modeling of Si in cool stellar atmospheres. Methods. Electronic molecular structure is determined using a recently proposed model approach based on an asymptotic method in combination with available ab initio potentials. Nonadiabatic nuclear dynamics are treated by means of a combination of multichannel formulas and the branching-probability-current method, based on the Landau-Zener model for nonadiabatic transition probabilities. Results. Cross sections and rate coefficients for inelastic processes in Si + H and Si+ + H- collisions for all transitions between 26 low-lying states plus the ionic state are calculated. It is shown that the highest rate coefficient values correspond to the excitation, de-excitation, ion-pair formation, and mutual neutralization processes involving the Si(3p4p D-3), Si(3p3d F-3), Si(3p4p D-1), Si(3p3d P-3), Si(3p4p S-1), and the ionic Si+ + H- states. These processes are likely to be important in non-LTE modeling.

  • 26. Bergemann, M.
    et al.
    Ruchti, G. R.
    Serenelli, A.
    Feltzing, S.
    Alves-Brito, A.
    Asplund, M.
    Bensby, T.
    Gruyters, Pieter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Hourihane, A.
    Korn, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Lind, K.
    Marino, A.
    Jofre, P.
    Nordlander, T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ryde, N.
    Worley, C. C.
    Gilmore, G.
    Randich, S.
    Ferguson, A. M. N.
    Jeffries, R. D.
    Micela, G.
    Negueruela, I.
    Prusti, T.
    Rix, H. -W
    Vallenari, A.
    Alfaro, E. J.
    Allende Prieto, C.
    Bragaglia, A.
    Koposov, S. E.
    Lanzafame, A. C.
    Pancino, E.
    Recio-Blanco, A.
    Smiljanic, R.
    Walton, N.
    Costado, M. T.
    Franciosini, E.
    Hill, V.
    Lardo, C.
    de Laverny, P.
    Magrini, L.
    Maiorca, E.
    Masseron, T.
    Morbidelli, L.
    Sacco, G.
    Kordopatis, G.
    Tautvaisiene, G.
    The Gaia-ESO Survey: radial metallicity gradients and age-metallicity relation of stars in the Milky Way disk2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 565, A89- p.Article in journal (Refereed)
    Abstract [en]

    We study the relationship between age, metallicity, and alpha-enhancement of FGK stars in the Galactic disk. The results are based upon the analysis of high-resolution UVES spectra from the Gaia-ESO large stellar survey. We explore the limitations of the observed dataset, i.e. the accuracy of stellar parameters and the selection effects that are caused by the photometric target preselection. We find that the colour and magnitude cuts in the survey suppress old metal-rich stars and young metal-poor stars. This suppression may be as high as 97% in some regions of the age-metallicity relationship. The dataset consists of 144 stars with a wide range of ages from 0.5 Gyr to 13.5 Gyr, Galactocentric distances from 6 kpc to 9.5 kpc, and vertical distances from the plane 0 < vertical bar Z vertical bar < 1.5 kpc. On this basis, we find that i) the observed age-metallicity relation is nearly flat in the range of ages between 0 Gyr and 8 Gyr; ii) at ages older than 9 Gyr, we see a decrease in [Fe/H] and a clear absence of metal-rich stars; this cannot be explained by the survey selection functions; iii) there is a significant scatter of [Fe/H] at any age; and iv) [Mg/Fe] increases with age, but the dispersion of [Mg/Fe] at ages > 9 Gyr is not as small as advocated by some other studies. In agreement with earlier work, we find that radial abundance gradients change as a function of vertical distance from the plane. The [Mg/Fe] gradient steepens and becomes negative. In addition, we show that the inner disk is not only more alpha-rich compared to the outer disk, but also older, as traced independently by the ages and Mg abundances of stars.

  • 27.
    Bergemann, Maria
    et al.
    Max Planck Inst Astron, D-69117 Heidelberg, Germany..
    Serenelli, Aldo
    Campus UAB, ICE CSIC IEEC, Inst Ciencias Espacio, Carrer Can Magrans S-N, Bellaterra 08193, Spain..
    Schonrich, Ralph
    Univ Oxford, Rudolf Peierls Ctr Theoret Phys, 1 Keble Rd, Oxford OX1 3NP, England..
    Ruchti, Greg
    Lund Observ, Box 43, S-22100 Lund, Sweden..
    Korn, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala Univ, Div Astron & Space Phys, Dept Phys & Astron, Angstrom Lab, Box 516, S-75120 Uppsala, Sweden..
    Hekker, Saskia
    Max Planck Inst Solar Syst Res, Justus von Liebig Weg 3, D-37077 Gttingen, Germany..
    Kovalev, Mikhail
    Max Planck Inst Astron, D-69117 Heidelberg, Germany..
    Mashonkina, Lyudmila
    Gilmore, Gerry
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Randich, Sofia
    INAF Osservatorio Astrofis Arcetri, Largo Fermi 5, I-50125 Florence, Italy..
    Asplund, Martin
    Australian Natl Univ, Mt Stromlo Observ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia..
    Rix, Hans-Walter
    Max Planck Inst Astron, D-69117 Heidelberg, Germany..
    Casey, Andrew R.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Jofre, Paula
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Pancino, Elena
    INAF Osservatorio Astron, Via Ranzani 1, I-40127 Bologna, Italy.;ASI Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy..
    Recio-Blanco, Alejandra
    Univ Nice Sophia Antipolis, CNRS, Observ Cote Azur, Lab Lagrange, BP 4229, F-06304 Nice 4, France..
    de Laverny, Patrick
    Univ Nice Sophia Antipolis, CNRS, Observ Cote Azur, Lab Lagrange, BP 4229, F-06304 Nice 4, France..
    Smiljanic, Rodolfo
    Nicolaus Copernicus Astron Ctr, Dept Astrophys, Ul Rabianska 8, PL-87100 Torun, Poland. Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munckegade 120, DK-8000 Aarhus, Denmark..
    Tautvaisiene, Grazina
    Vilnius Univ, Inst Theoret Phys & Astron, Gostauto 12, LT-01108 Vilnius, Lithuania..
    Bayo, Amelia
    Inst Fis & Astron, Fac Ciencias, Gran Bretana 1111, Playa Ancha, Chile..
    Lewis, Jim
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Koposov, Sergey
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Hourihane, Anna
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Worley, Clare
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Morbidelli, Lorenzo
    INAF Osservatorio Astrofis Arcetri, Largo Fermi 5, I-50125 Florence, Italy..
    Franciosini, Elena
    INAF Osservatorio Astrofis Arcetri, Largo Fermi 5, I-50125 Florence, Italy..
    Sacco, Germano
    INAF Osservatorio Astrofis Arcetri, Largo Fermi 5, I-50125 Florence, Italy..
    Magrini, Laura
    INAF Osservatorio Astrofis Arcetri, Largo Fermi 5, I-50125 Florence, Italy..
    Damiani, Francesco
    INAF Osservatorio Astron Palermo, Piazza Parlamento 1, I-90134 Palermo, Italy. Russian Acad Sci, Inst Astron, Pyatnitskaya St 48, Moscow 119017, Russia..
    Bestenlehner, Joachim M.
    The Gaia-ESO Survey: Hydrogen lines in red giants directly trace stellar mass2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 594, A120Article in journal (Refereed)
    Abstract [en]

    Red giant stars are perhaps the most important type of stars for Galactic and extra-galactic archaeology: they are luminous, occur in all stellar populations, and their surface temperatures allow precise abundance determinations for many different chemical elements. Yet, the full star formation and enrichment history of a galaxy can be traced directly only if two key observables can be determined for large stellar samples: age and chemical composition. While spectroscopy is a powerful method to analyse the detailed abundances of stars, stellar ages are the missing link in the chain, since they are not a direct observable. However, spectroscopy should be able to estimate stellar masses, which for red giants directly infer ages provided their chemical composition is known. Here we establish a new empirical relation between the shape of the hydrogen line in the observed spectra of red giants and stellar mass determined from asteroseismology. The relation allows determining stellar masses and ages with an accuracy of 10-15%. The method can be used with confidence for stars in the following range of stellar parameters: 4000 < T-eff < 5000 K, 0.5 < log g < 3.5, -2.0 < [ Fe/H] < 0.3, and luminosities log L/L-Sun < 2.5. Our analysis provides observational evidence that the H-alpha spectral characteristics of red giant stars are tightly correlated with their mass and therefore their age. We also show that the method samples well all stellar populations with ages above 1 Gyr. Targeting bright giants, the method allows obtaining simultaneous age and chemical abundance information far deeper than would be possible with asteroseismology, extending the possible survey volume to remote regions of the Milky Way and even to neighbouring galaxies such as Andromeda or the Magellanic Clouds even with current instrumentation, such as the VLT and Keck facilities.

  • 28.
    Bergvall, Nils
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Leitet, Elisabet
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Zackrisson, Erik
    Department of Astronomy, Stockholm University, Oscar Klein Center, AlbaNova, Stockholm.
    Marquart, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Lyman continuum leaking galaxies: Search strategies and local candidates2013In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 554, A38- p.Article in journal (Other academic)
    Abstract [en]

    Context. Star-forming dwarf galaxies may have played an important role in the reionization of the Universe, provided that some fraction of their ionizing radiation were able to escape into the intergalactic medium. Local galaxies exhibiting such Lyman-continuum(LyC) leakage could potentially shed light on the escape mechanisms involved, but only two low-redshift cases of LyC leakage have been identified so far. Here, we argue that this meager harvest may be caused by unsuitable selection criteria. Candidates for LyC leakage are normally selected by indicators of starburst activity, one of which is a high equivalent width in H alpha. Such a criterion will guarantee a high production of LyC photons but will also bias the selection in favour of a high column density in the neutral gas, effectively ruling out LyC escape. Aims. In this work we want to investigate whether the lack of local LyC emitters can be caused in part by biased selection criteria, and we present a novel method of selecting targets with high escape fractions. By applying these criteria, we assemble a sample of observation targets to study their basic properties. Methods. We introduce a new selection strategy here where the potential LyC leakers are selected by their blue colours and weak emission lines. The selection is based on data from the Sloan Digital Sky Survey (SDSS). We also take a closer look at the properties of 8 LyCleaking candidates at z similar to 0.03 which we have observed with ESO/NTT in broadband B and H alpha. Results. We find that 7 of the 8 target galaxies are involved in interaction with neighbours or show signs of mergers. In 7 cases the young stellar population is clearly displaced relative to the main body of these galaxies, often directly bordering the halo region. In about half of our targets the absorption spectra show young post-starburst signatures. Comparing the scale lengths in H alpha with those of the stellar continua shows that the scale lengths in H alpha typically are 30% smaller, which is characteristic of galaxies influenced by ram pressure stripping. We tentatively identify a few mechanisms that could improve the conditions for leakage: 1) the combined effects of ram pressure stripping with supernova winds from young stars formed in the front, 2) merger events that increase the star formation rate and displace stars from gas, 3) starbursts in the centres of post-starburst galaxies, whose previous activity has cleared channels for leakage into the intergalactic medium, and 4) a low dust content. Although our target galaxies are rare species in the local universe, we argue that related types could have played a major role in producing ionizing radiation at high redshifts.

  • 29.
    Bergvall, Nils
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Marquart, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Way, Michael J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. NASA Goddard Institute for Space Studies, 2880 Broadway, New York 10025, USA.
    Blomqvist, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Holst, Emma
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Östlin, Göran
    Stockholm Univ, Dept Astron, S-10691 Stockholm, Sweden.
    Zackrisson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Local starburst galaxies and their descendants: Statistics from the Sloan Digital Sky Survey2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 587, A72Article in journal (Refereed)
    Abstract [en]

    Aims: Despite strong interest in the starburst phenomenon in extragalactic astronomy, the concept remains ill-defined. Here we use a strict definition of starburst to examine the statistical properties of starburst galaxies in the local universe. We also seek to establish links between starburst galaxies, post-starburst (hereafter postburst) galaxies, and active galaxies.

    Methods: Data were selected from the Sloan Digital Sky Survey DR7. We applied a novel method of treating dust attenuation and derive star formation rates, ages, and stellar masses assuming a two-component stellar population model. Dynamical masses are calculated from the width of the H alpha line. These masses agree excellently with the photometric masses. The mass (gas + stars) range is similar to 10(9)-10(11.5) M-circle dot. As a selection criterion for starburst galaxies, we use, the birthrate parameter, b = SFR/< SFR >, requiring that b >= 3. For postburst galaxies, we use, the equivalent width of H delta in absorption with the criterion EWH delta,abs >= 6 angstrom.

    Results: We find that only 1% of star-forming galaxies are starburst galaxies. They contribute 3 6% to the stellar production and are therefore unimportant for the local star formation activity. The median starburst age is 70 Myr roughly independent of mass, indicating that star formation is mainly regulated by local feedback processes. The b-parameter strongly depends on burst age. Values close to b = 60 are found at ages similar to 10 Myr, while almost no starbursts are found at ages >1 Gyr. The median baryonic burst mass fraction of sub-L* galaxies is 5% and decreases slowly towards high masses. The median mass fraction of the recent burst in the postburst sample is 5-10%. A smaller fraction of the postburst galaxies, however, originates in non-bursting galaxies. The age-mass distribution of the postburst progenitors (with mass fractions >3%) is bimodal with a break at log M (M-circle dot) similar to 10.6, above which the ages are doubled. The starburst and postburst luminosity functions (LFs) follow each other closely until M-r similar to -21, when active galactic nuclei (AGNs) begin to dominate. The postburst LF continues to follow the AGN LF, while starbursts become less significant. This suggests that the number of luminous starbursts is underestimated by about one dex at high luminosities, because of having large amounts of dust and/or being outshone by an AGN. It also indicates that the starburst phase preceded the AGN phase. Finally, we look at the conditions for global gas outflow caused by stellar feedback and find that massive starburst galaxies are susceptible to such outflows.

  • 30.
    Bertini, I.
    et al.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Moreno, F.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Pajola, M.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Lamy, P.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon Pricipal, France..
    Bertaux, J. -L
    Cremonese, G.
    INAF Osservatorio Astron Padova, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    Univ Padua, Dept Ind Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trent, UNITN, I-38100 Trento, Italy..
    Ferri, F.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon Pricipal, France.;Univ Paris Diderot, Sorbonne Paris Cite, F-75205 Paris 13, France..
    Fulle, M.
    INAF Osservatorio Astron Trieste, I-34143 Trieste, Italy..
    Giacomini, L.
    Univ Padua, Dept Geosci, I-35131 Padua, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S. F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France..
    Knollenberg, J.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kuehrt, E.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kueppers, M.
    ESA ESAC, Villanueva De La Canada 28691, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Magrin, S.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Massironi, M.
    Univ Padua, Dept Geosci, I-35131 Padua, Italy..
    Michalik, H.
    Inst Datentech & Kommunikat Netze, D-38106 Braunschweig, Germany..
    Mottola, S.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Naletto, G.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy.;CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Search for satellites near comet 67P/Churyumov-Gerasimenko using Rosetta/OSIRIS images2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, A19Article in journal (Refereed)
    Abstract [en]

    Context. The European Space Agency Rosetta mission reached and started escorting its main target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, at the beginning of August 2014. Within the context of solar system small bodies, satellite searches from approaching spacecraft were extensively used in the past to study the nature of the visited bodies and their collisional environment. Aims. During the approaching phase to the comet in July 2014, the OSIRIS instrument onboard Rosetta performed a campaign aimed at detecting objects in the vicinity of the comet nucleus and at measuring these objects' possible bound orbits. In addition to the scientific purpose, the search also focused on spacecraft security to avoid hazardous material in the comet's environment. Methods. Images in the red spectral domain were acquired with the OSIRIS Narrow Angle Camera, when the spacecraft was at a distance between 5785 km and 5463 km to the comet, following an observational strategy tailored to maximize the scientific outcome. From the acquired images, sources were extracted and displayed to search for plausible displacements of all sources from image to image. After stars were identified, the remaining sources were thoroughly analyzed. To place constraints on the expected displacements of a potential satellite, we performed Monte Carlo simulations on the apparent motion of potential satellites within the Hill sphere. Results. We found no unambiguous detections of objects larger than similar to 6 m within similar to 20 km and larger than similar to 1 m between similar to 20 km and similar to 110 km from the nucleus, using images with an exposure time of 0.14 s and 1.36 s, respectively. Our conclusions are consistent with independent works on dust grains in the comet coma and on boulders counting on the nucleus surface. Moreover, our analysis shows that the comet outburst detected at the end of April 2014 was not strong enough to eject large objects and to place them into a stable orbit around the nucleus. Our findings underline that it is highly unlikely that large objects survive for a long time around cometary nuclei.

  • 31.
    Bladh, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Höfner, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Exploring wind-driving dust species in cool luminous giants: I. Basic criteria and dynamical models of M-type AGB stars2012In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 546, A76- p.Article in journal (Refereed)
    Abstract [en]

    Context. The heavy mass loss observed in evolved asymptotic giant branch stars is usually attributed to a two-stage process: atmospheric levitation by pulsation-induced shock waves followed by radiative acceleration of dust grains, which transfer momentum to the surrounding gas through collisions. In order for an outflow to occur the two stages of the mass-loss scheme have to connect, i.e., the radiative acceleration can only be initiated if the levitated gas reaches a distance from the stellar photosphere where dust particles can condense. This levitation distance is limited by the kinetic energy transferred to the gas by the shock waves, which imposes strict constraints on potential wind-driving dust species. Aims. This work is part of an ongoing effort aiming at identifying the actual wind-drivers among the dust species observed in circumstellar envelopes. In particular, we focus on the interplay between a strong stellar radiation field and the dust formation process. Methods. To identify critical properties of potential wind-driving dust species we use detailed radiation-hydrodynamical models which include a parameterized dust description, complemented by simple analytical estimates to help with the physical interpretation of the numerical results. The adopted dust description is constructed to mimic different chemical and optical dust properties in order to systematically study the effects of a realistic radiation field on the second stage of the mass loss mechanism. Results. We see distinct trends in which combinations of optical and chemical dust properties are needed to trigger an outflow. Dust species with a low condensation temperature and a near-infrared absorption coefficient that decreases strongly with wavelength will not condense close enough to the stellar surface to be considered as potential wind-drivers. Conclusions. Our models confirm that metallic iron and Fe-bearing silicates are not viable as wind-drivers due to their near-infrared optical properties and resulting large condensation distances. TiO2 is also excluded as a wind-driver due to the low abundance of Ti. Other species, such a SiO2 and Al2O3, are less clear-cut cases due to uncertainties in the optical and chemical data and further work is needed. A strong candidate is Mg2SiO4 with grain sizes of 0.1-1 mu m, where scattering contributes significantly to the radiative acceleration, as suggested by earlier theoretical work and supported by recent observations.

  • 32.
    Bladh, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Höfner, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Nowotny, W.
    Aringer, B.
    Eriksson, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Exploring wind-driving dust species in cool luminous giants II. Constraints from photometry of M-type AGB stars2013In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 553, A20- p.Article in journal (Refereed)
    Abstract [en]

    Context. The heavy mass loss observed in evolved asymptotic giant branch (AGB) stars is usually attributed to a two-stage process: atmospheric levitation by pulsation-induced shock waves, followed by radiative acceleration of newly formed dust grains. The dust transfers momentum to the surrounding gas through collisions and thereby triggers a general outflow. Radiation-hydrodynamical models of M-type AGB stars suggest that these winds can be driven by photon scattering - in contrast to absorption - on Fe-free silicate grains of sizes 0.1-1 mu m. Aims. In this paper we study photometric constraints for wind-driving dust species in M-type AGB stars, as part of an ongoing effort to identify likely candidates among the grain materials observed in circumstellar envelopes. Methods. To investigate the scenario of stellar winds driven by photon scattering on dust, and to explore how different optical and chemical properties of wind-driving dust species affect photometry we focus on two sets of dynamical models atmospheres: (i) models using a detailed description for the growth of Mg2SiO4 grains, taking into account both scattering and absorption cross-sections when calculating the radiative acceleration; and (ii) models using a parameterized dust description, constructed to represent different chemical and optical dust properties. By comparing synthetic photometry from these two sets of models to observations of M-type AGB stars we can provide constraints on the properties of wind-driving dust species. Results. Photometry from wind models with a detailed description for the growth of Mg2SiO4 grains reproduces well both the values and the time-dependent behavior of observations of M-type AGB stars, providing further support for the scenario of winds driven by photon scattering on dust. The photometry from the models with a parameterized dust description suggests that wind-drivers need to have a low absorption cross-section in the visual and near-IR to reproduce the time-dependent behavior, i. e. small variations in (J-K) and spanning a larger range in (V-K). This places constraints on the optical and chemical properties of the wind-driving dust species. Conclusions. To reproduce the observed photometric variations in (V-K) and (J-K) both detailed and parameterized models suggest that the wind-driving dust materials have to be quite transparent in the visual and near-IR. Consequently, strong candidates for outflows driven by photon scattering on dust grains are Mg2SiO4, MgSiO3, and potentially SiO2.

  • 33.
    Bladh, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Susanne, Höfner
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Aringer, Bernhard
    Eriksson, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Exploring wind-driving dust species in cool luminous giants III: Wind models for M-type AGB stars2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 575, A105Article in journal (Refereed)
  • 34. Blanco-Cuaresma, S.
    et al.
    Soubiran, C.
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Asplund, M.
    Carraro, G.
    Costado, M. T.
    Feltzing, S.
    Gonzalez-Hernandez, J. I.
    Jimenez-Esteban, F.
    Korn, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Marino, A. F.
    Montes, D.
    San Roman, I.
    Tabernero, H. M.
    Tautvaisiene, G.
    Testing the chemical tagging technique with open clusters2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 577, A47Article in journal (Refereed)
    Abstract [en]

    Context. Stars are born together from giant molecular clouds and, if we assume that the priors were chemically homogeneous and well-mixed, we expect them to share the same chemical composition. Most of the stellar aggregates are disrupted while orbiting the Galaxy and most of the dynamic information is lost, thus the only possibility of reconstructing the stellar formation history is to analyze the chemical abundances that we observe today. Aims. The chemical tagging technique aims to recover disrupted stellar clusters based merely on their chemical composition. We evaluate the viability of this technique to recover co-natal stars that are no longer gravitationally bound. Methods. Open clusters are co-natal aggregates that have managed to survive together. We compiled stellar spectra from 31 old and intermediate-age open clusters, homogeneously derived atmospheric parameters, and 17 abundance species, and applied machine learning algorithms to group the stars based on their chemical composition. This approach allows us to evaluate the viability and efficiency of the chemical tagging technique. Results. We found that stars at different evolutionary stages have distinct chemical patterns that may be due to NLTE effects, atomic diffusion, mixing, and biases. When separating stars into dwarfs and giants, we observed that a few open clusters show distinct chemical signatures while the majority show a high degree of overlap. This limits the recovery of co-natal aggregates by applying the chemical tagging technique. Nevertheless, there is room for improvement if more elements are included and models are improved.

  • 35. Blanco-Cuaresma, S.
    et al.
    Soubiran, C.
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Jofre, P.
    Determining stellar atmospheric parameters and chemical abundances of FGK stars with iSpec2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 569, A111- p.Article in journal (Refereed)
    Abstract [en]

    Context. An increasing number of high-resolution stellar spectra is available today thanks to many past and ongoing extensive spectroscopic surveys. Consequently, the scientific community needs automatic procedures to derive atmospheric parameters and individual element abundances. Aims. Based on the widely known SPECTRUM code by R.O. Gray, we developed an integrated spectroscopic software framework suitable for the determination of atmospheric parameters (i.e., effective temperature, surface gravity, metallicity) and individual chemical abundances. The code, named iSpec and freely distributed, is written mainly in Python and can be used on different platforms. Methods. iSpec can derive atmospheric parameters by using the synthetic spectral fitting technique and the equivalent width method. We validated the performance of both approaches by developing two different pipelines and analyzing the Gaia FGK benchmark stars spectral library. The analysis was complemented with several tests designed to assess other aspects, such as the interpolation of model atmospheres and the performance with lower quality spectra. Results. We provide a code ready to perform automatic stellar spectral analysis. We successfully assessed the results obtained for FGK stars with high-resolution and high signal-to-noise spectra.

  • 36. Blanco-Cuaresma, S.
    et al.
    Soubiran, C.
    Jofre, P.
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    The Gaia FGK benchmark stars High resolution spectral library2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 566, A98- p.Article in journal (Refereed)
    Abstract [en]

    Context. An increasing number of high-resolution stellar spectra is available today thanks to many past and ongoing spectroscopic surveys. Consequently, numerous methods have been developed to perform an automatic spectral analysis on a massive amount of data. When reviewing published results, biases arise and they need to be addressed and minimized. Aims. We are providing a homogeneous library with a common set of calibration stars (known as the Gaia FGK benchmark stars) that will allow us to assess stellar analysis methods and calibrate spectroscopic surveys. Methods. High-resolution and signal-to-noise spectra were compiled from different instruments. We developed an automatic process to homogenize the observed data and assess the quality of the resulting library. Results. We built a high-quality library that will facilitate the assessment of spectral analyses and the calibration of present and future spectroscopic surveys. The automation of the process minimizes the human subjectivity and ensures reproducibility. Additionally, it allows us to quickly adapt the library to specific needs that can arise from future spectroscopic analyses.

  • 37. Bonifacio, P.
    et al.
    Spite, M.
    Cayrel, R.
    Hill, V.
    Spite, F.
    Francois, P.
    Plez, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ludwig, H. -G
    Caffau, E.
    Molaro, P.
    Depagne, E.
    Andersen, J.
    Barbuy, B.
    Beers, T. C.
    Nordström, B.
    Primas, F.
    First stars XII. Abundances in extremely metal-poor turnoff stars, and comparison with the giants2009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 501, no 2, 519-530 p.Article in journal (Refereed)
    Abstract [en]

    Context. The detailed chemical abundances of extremely metal-poor (EMP) stars are key guides to understanding the early chemical evolution of the Galaxy. Most existing data, however, treat giant stars that may have experienced internal mixing later. Aims. We aim to compare the results for giants with new, accurate abundances for all observable elements in 18 EMP turno. stars. Methods. VLT/UVES spectra at R similar to 45 000 and S/N similar to 130 per pixel (lambda lambda 330-1000 nm) are analysed with OSMARCS model atmospheres and the TURBOSPECTRUM code to derive abundances for C, Mg, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Sr, and Ba. Results. For Ca, Ni, Sr, and Ba, we find excellent consistency with our earlier sample of EMP giants, at all metallicities. However, our abundances of C, Sc, Ti, Cr, Mn and Co are similar to 0.2 dex larger than in giants of similar metallicity. Mg and Si abundances are similar to 0.2 dex lower (the giant [Mg/Fe] values are slightly revised), while Zn is again similar to 0.4 dex higher than in giants of similar [Fe/H] (6 stars only). Conclusions. For C, the dwarf/giant discrepancy could possibly have an astrophysical cause, but for the other elements it must arise from shortcomings in the analysis. Approximate computations of granulation (3D) effects yield smaller corrections for giants than for dwarfs, but suggest that this is an unlikely explanation, except perhaps for C, Cr, and Mn. NLTE computations for Na and Al provide consistent abundances between dwarfs and giants, unlike the LTE results, and would be highly desirable for the other discrepant elements as well. Meanwhile, we recommend using the giant abundances as reference data for Galactic chemical evolution models.

  • 38. Bouchy, F.
    et al.
    Hebb, L.
    Skillen, I.
    Cameron, A. Collier
    Smalley, B.
    Udry, S.
    Anderson, D. R.
    Boisse, I.
    Enoch, B.
    Haswell, C. A.
    Hebrard, G.
    Hellier, C.
    Joshi, Y.
    Kane, S. R.
    Maxted, P. F. L.
    Mayor, M.
    Moutou, C.
    Pepe, F.
    Pollacco, D.
    Queloz, D.
    Segransan, D.
    Simpson, E. K.
    Smith, A. M. S.
    Stempels, H. C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Street, R.
    Triaud, A. H. M. J.
    West, R. G.
    Wheatley, P. J.
    WASP-21b: a hot-Saturn exoplanet transiting a thick disc star2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 519, A98- p.Article in journal (Refereed)
    Abstract [en]

    We report the discovery of WASP-21b, a new transiting exoplanet discovered by the Wide Angle Search for Planets ( WASP) Consortium and established and characterized with the FIES, SOPHIE, CORALIE and HARPS fiber-fed echelle spectrographs. A 4.3-d period, 1.1% transit depth and 3.4-h duration are derived for WASP-21b using SuperWASP-North and high precision photometric observations at the Liverpool Telescope. Simultaneous fitting to the photometric and radial velocity data with a Markov Chain Monte Carlo procedure leads to a planet in the mass regime of Saturn. With a radius of 1.07 R-Jup and mass of 0.30 M-Jup, WASP-21b has a density close to 0.24 rho(Jup) corresponding to the distribution peak at low density of transiting gaseous giant planets. With a host star metallicity [Fe/H] of -0.46, WASP-21b strengthens the correlation between planetary density and host star metallicity for the five known Saturn-like transiting planets. Furthermore there are clear indications that WASP-21b is the first transiting planet belonging to the thick disc.

  • 39.
    Brown, A. G. A.
    et al.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands..
    Vallenari, A.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Prusti, T.
    European Space Res & Technol Ctr ESA ESTEC, Directorate Sci, Sci Support Off, Keplerlaan 1, NL-2201AZ Noordwijk, Netherlands..
    de Bruijne, J. H. J.
    European Space Res & Technol Ctr ESA ESTEC, Directorate Sci, Sci Support Off, Keplerlaan 1, NL-2201AZ Noordwijk, Netherlands..
    Mignard, F.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Drimmel, R.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Babusiaux, C.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Bailer-Jones, C. A. L.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany..
    Bastian, U.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Biermann, M.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Evans, D. W.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Eyer, L.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland..
    Jansen, F.
    European Space Res & Technol Ctr ESA ESTEC, Directorate Sci, Operat Dept, Mission Operat Div, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands..
    Jordi, C.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Katz, D.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Klioner, S. A.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany..
    Lammers, U.
    European Space Astron Ctr ESA ESAC, Camino Bajo dell Castillo S-N, Madrid 28692, Spain..
    Lindegren, L.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Luri, X.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    O'Mullane, W.
    European Space Astron Ctr ESA ESAC, Camino Bajo dell Castillo S-N, Madrid 28692, Spain..
    Panem, C.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Pourbaix, D.
    Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226,Blvd Triomphe, B-1050 Brussels, Belgium.;FRS FNRS, Rue Egmont 5, B-1000 Brussels, Belgium..
    Randich, S.
    Osserv Astrofis Arcetri, INAF, Largo Enrico Fermi 5, I-50125 Florence, Italy..
    Sartoretti, P.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Siddiqui, H. I.
    Telespazio Vega UK Ltd, ESA ESAC, Camino Bajo del Castillo, Madrid 28692, Spain..
    Soubiran, C.
    Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Valette, V.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    van Leeuwen, F.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Walton, N. A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Aerts, C.
    Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium.;Radboud Univ Nijmegen, IMAPP, Dept Astrophys, POB 9010, NL-6500 GL Nijmegen, Netherlands..
    Arenou, F.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Cropper, M.
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England..
    Hog, E.
    Univ Copenhagen, Niels Bohr Inst, Juliane Maries Vej 30, DK-2100 Copenhagen O, Denmark..
    Lattanzi, M. G.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Grebel, E. K.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Holland, A. D.
    Open Univ, Dept Phys Sci, Ctr Elect Imaging, Walton Hall, Milton Keynes MK7 6AA, Bucks, England..
    Huc, C.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Passot, X.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Perryman, M.
    European Space Res & Technol Ctr ESA ESTEC, Directorate Sci, Sci Support Off, Keplerlaan 1, NL-2201AZ Noordwijk, Netherlands..
    Bramante, L.
    ALTEC Spa, Corso Marche 79, I-10146 Turin, Italy..
    Cacciari, C.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Castaneda, J.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Chaoul, L.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Cheek, N.
    Serco Gest Negocios ESA ESAC, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    De Angeli, F.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Fabricius, C.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Guerra, R.
    European Space Astron Ctr ESA ESAC, Camino Bajo dell Castillo S-N, Madrid 28692, Spain..
    Hernandez, J.
    European Space Astron Ctr ESA ESAC, Camino Bajo dell Castillo S-N, Madrid 28692, Spain..
    Jean-Antoine-Piccolo, A.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Masana, E.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Messineo, R.
    ALTEC Spa, Corso Marche 79, I-10146 Turin, Italy..
    Mowlavi, N.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland..
    Nienartowicz, K.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Ordonez-Blanco, D.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Panuzzo, P.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Portell, J.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Richards, P. J.
    Rutherford Appleton Lab, STFC, Didcot OX11 0QX, Oxon, England..
    Riello, M.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Seabroke, G. M.
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England..
    Tanga, P.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Thevenin, F.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Torra, J.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Els, S. G.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany.;ESAC, Gaia DPAC Project Off, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Gracia-Abril, G.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain.;ESAC, Gaia DPAC Project Off, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Comoretto, G.
    Telespazio Vega UK Ltd, ESA ESAC, Camino Bajo del Castillo, Madrid 28692, Spain..
    Garcia-Reinaldos, M.
    European Space Astron Ctr ESA ESAC, Camino Bajo dell Castillo S-N, Madrid 28692, Spain..
    Lock, T.
    European Space Astron Ctr ESA ESAC, Camino Bajo dell Castillo S-N, Madrid 28692, Spain..
    Mercier, E.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany.;ESAC, Gaia DPAC Project Off, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Altmann, M.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany.;UPMC Univ Paris 06, PSL Res Univ, CNRS, SYRTE,Observ Paris,Sorbonne Univ,LNE, 61 Ave Observ, F-75014 Paris, France..
    Andrae, R.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany..
    Astraatmadja, T. L.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany..
    Bellas-Velidis, I.
    Natl Observ Athens, Athens 15236, Greece..
    Benson, K.
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England..
    Berthier, J.
    UPMC Univ Paris 06, PSL Res Univ, IMCCE, Observ Paris,CNRS,Sorbonne Univ,Univ Lille, 77 Av Denfert Rochereau, F-75014 Paris, France..
    Blomme, R.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    Busso, G.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Carry, B.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France.;UPMC Univ Paris 06, PSL Res Univ, IMCCE, Observ Paris,CNRS,Sorbonne Univ,Univ Lille, 77 Av Denfert Rochereau, F-75014 Paris, France..
    Cellino, A.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Clementini, G.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Cowell, S.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Creevey, O.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France.;Univ Paris XI, CNRS, Inst Astrophys Spatiale, UMR 8617, Batiment 121, F-91405 Orsay, France..
    Cuypers, J.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    Davidson, M.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    De Ridder, J.
    Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium..
    de Torres, A.
    ESA ESAC, HE Space Operat BV, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Delchambre, L.
    Univ Liege, Inst Astrophys & Geophys, 19c,Allee 6 Aout, B-4000 Liege, Belgium..
    Dell'Oro, A.
    Osserv Astrofis Arcetri, INAF, Largo Enrico Fermi 5, I-50125 Florence, Italy..
    Ducourant, C.
    Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Fremat, Y.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    Garcia-Torres, M.
    Univ Pablo de Olavide, Area Lenguajes & Sistemas Informat, Ctra Utrera,Km 1, Seville 41013, Spain..
    Gosset, E.
    FRS FNRS, Rue Egmont 5, B-1000 Brussels, Belgium.;Univ Liege, Inst Astrophys & Geophys, 19c,Allee 6 Aout, B-4000 Liege, Belgium..
    Halbwachs, J. -L
    Hambly, N. C.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Harrison, D. L.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.;Univ Cambridge, Kavli Inst Cosmol, Madingley Rd, Cambridge CB3 0HA, England..
    Hauser, M.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Hestroffer, D.
    UPMC Univ Paris 06, PSL Res Univ, IMCCE, Observ Paris,CNRS,Sorbonne Univ,Univ Lille, 77 Av Denfert Rochereau, F-75014 Paris, France..
    Hodgkin, S. T.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Huckle, H. E.
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England..
    Hutton, A.
    ESA ESAC, Aurora Technol, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Jasniewicz, G.
    Univ Montpellier, Lab Univers & Particules Montpellier, Pl Eugene Bataillon,CC72, F-34095 Montpellier 05, France..
    Jordan, S.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Kontizas, M.
    Univ Athens, Dept Astrophys Astron & Mech, Athens 15783, Greece..
    Korn, Andreas J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Lanzafame, A. C.
    Univ Catania, Dipartimento Fis & Astron, Sez Astrofis, Via S Sofia 78, I-95123 Catania, Italy.;Osserv Astrofis Catania, INAF, Via S Sofia 78, I-95123 Catania, Italy..
    Manteiga, M.
    Univ A Coruna, Fac Informat, Campus Elvina S-N, La Coruna 15071, Spain..
    Moitinho, A.
    Univ Lisbon, CENTRA, FCUL, Edif C8, P-1749016 Lisbon, Portugal..
    Muinonen, K.
    Univ Helsinki, Dept Phys, POB 64, FIN-00014 Helsinki, Finland.;Finnish Geospatial Res Inst FGI, Geodeetinrinne 2, Masala 02430, Finland..
    Osinde, J.
    ESA ESAC, Isdefe, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Pancino, E.
    Osserv Astrofis Arcetri, INAF, Largo Enrico Fermi 5, I-50125 Florence, Italy.;ASI Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy..
    Pauwels, T.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    Petit, J. -M
    Recio-Blanco, A.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Robin, A. C.
    Univ Bourgogne Franche Comte, OSU THETA Franche Comte Bourgogne, CNRS, Inst UTINAM UMR6213, F-25000 Besancon, France..
    Sarro, L. M.
    UNED, Dept Inteligencia Artificial, C Juan del Rosal 16, Madrid 28040, Spain..
    Siopis, C.
    Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226,Blvd Triomphe, B-1050 Brussels, Belgium..
    Smith, M.
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England..
    Smith, K. W.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany..
    Sozzetti, A.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Thuillot, W.
    UPMC Univ Paris 06, PSL Res Univ, IMCCE, Observ Paris,CNRS,Sorbonne Univ,Univ Lille, 77 Av Denfert Rochereau, F-75014 Paris, France..
    van Reeven, W.
    ESA ESAC, Aurora Technol, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Viala, Y.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Abbas, U.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Aramburu, A. Abreu
    ESA ESAC, Elecnor Deimos Space, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Accart, S.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Aguado, J. J.
    UNED, Dept Inteligencia Artificial, C Juan del Rosal 16, Madrid 28040, Spain..
    Allan, P. M.
    Rutherford Appleton Lab, STFC, Didcot OX11 0QX, Oxon, England..
    Allasia, W.
    EURIX Srl, Via Carcano 26, I-10153 Turin, Italy..
    Altavilla, G.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Alvarez, M. A.
    Univ A Coruna, Fac Informat, Campus Elvina S-N, La Coruna 15071, Spain..
    Alves, J.
    Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria..
    Anderson, R. I.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.;Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA..
    Andrei, A. H.
    UPMC Univ Paris 06, PSL Res Univ, CNRS, SYRTE,Observ Paris,Sorbonne Univ,LNE, 61 Ave Observ, F-75014 Paris, France.;ON MCTI BR, Rua Gal Jose Cristino 77, BR-20921400 Rio De Janeiro, RJ, Brazil.;OV UFRJ BR, Ladeira Pedro Antonio 43, BR-20080090 Rio De Janeiro, RJ, Brazil..
    Varela, E. Anglada
    Serco Gest Negocios ESA ESAC, Camino Bajo del Castillo S-N, Madrid 28692, Spain.;ESA ESAC, Isdefe, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Antiche, E.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Antoja, T.
    European Space Res & Technol Ctr ESA ESTEC, Directorate Sci, Sci Support Off, Keplerlaan 1, NL-2201AZ Noordwijk, Netherlands..
    Anton, S.
    Univ Porto, Fac Ciencias, Dept Matemat, Rua Campo Alegre 687, P-4169007 Oporto, Portugal.;Univ Lisbon, Inst Astrofis & Ciencias Espaco, Fac Ciencias, P-1749016 Lisbon, Portugal..
    Arcay, B.
    Univ A Coruna, Fac Informat, Campus Elvina S-N, La Coruna 15071, Spain..
    Bach, N.
    ESA ESAC, Aurora Technol, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Baker, S. G.
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England..
    Balaguer-Nunez, L.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Barache, C.
    UPMC Univ Paris 06, PSL Res Univ, CNRS, SYRTE,Observ Paris,Sorbonne Univ,LNE, 61 Ave Observ, F-75014 Paris, France..
    Barata, C.
    Univ Lisbon, CENTRA, FCUL, Edif C8, P-1749016 Lisbon, Portugal..
    Barbier, A.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Barblan, F.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland..
    Barrado y Navascues, D.
    ESA ESAC, Ctr Astrobiol CSIC INTA, Dept Astrofis, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Barros, M.
    Univ Lisbon, CENTRA, FCUL, Edif C8, P-1749016 Lisbon, Portugal..
    Barstow, M. A.
    Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England..
    Becciani, U.
    Osserv Astrofis Catania, INAF, Via S Sofia 78, I-95123 Catania, Italy..
    Bellazzini, M.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Garcia, A. Bello
    Univ Oviedo, Campus Univ, Gijon 33203, Spain..
    Belokurov, V.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Bendjoya, P.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Berihuete, A.
    Univ Cadiz, Avd Univ, Cadiz 11002, Spain..
    Bianchi, L.
    EURIX Srl, Via Carcano 26, I-10153 Turin, Italy..
    Bienayme, O.
    Univ Strasbourg, Observ Astron Strasbourg, CNRS, UMR 7550, 11 Rue Univ, F-67000 Strasbourg, France..
    Billebaud, F.
    Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Blagorodnova, N.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Blanco-Cuaresma, S.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.;Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Boch, T.
    Univ Strasbourg, Observ Astron Strasbourg, CNRS, UMR 7550, 11 Rue Univ, F-67000 Strasbourg, France..
    Bombrun, A.
    ESA ESAC, HE Space Operat BV, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Borrachero, R.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Bouquillon, S.
    UPMC Univ Paris 06, PSL Res Univ, CNRS, SYRTE,Observ Paris,Sorbonne Univ,LNE, 61 Ave Observ, F-75014 Paris, France..
    Bourda, G.
    Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Bouy, H.
    ESA ESAC, Ctr Astrobiol CSIC INTA, Dept Astrofis, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Bragaglia, A.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Breddels, M. A.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands..
    Brouillet, N.
    Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Bruesemeister, T.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Bucciarelli, B.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Burgess, P.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Burgon, R.
    Open Univ, Dept Phys Sci, Ctr Elect Imaging, Walton Hall, Milton Keynes MK7 6AA, Bucks, England..
    Burlacu, A.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Busonero, D.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Buzzi, R.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Caffau, E.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Cambras, J.
    Univ Catalunya, Consorci Serv, C Gran Capita 2-4 3rd Floor, Barcelona 08034, Spain..
    Campbell, H.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Cancelliere, R.
    Univ Turin, Dept Comp Sci, Corso Svizzera 185, I-10149 Turin, Italy..
    Cantat-Gaudin, T.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Carlucci, T.
    UPMC Univ Paris 06, PSL Res Univ, CNRS, SYRTE,Observ Paris,Sorbonne Univ,LNE, 61 Ave Observ, F-75014 Paris, France..
    Carrasco, J. M.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Castellani, M.
    Osserv Astron Roma, INAF, Via Frascati 33, I-00078 Rome, Italy..
    Charlot, P.
    Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Charnas, J.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Chiavassa, A.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Clotet, M.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Cocozza, G.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Collins, R. S.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Costigan, G.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands..
    Crifo, F.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Cross, N. J. G.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Crosta, M.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Crowley, C.
    ESA ESAC, HE Space Operat BV, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Dafonte, C.
    Univ A Coruna, Fac Informat, Campus Elvina S-N, La Coruna 15071, Spain..
    Damerdji, Y.
    Univ Liege, Inst Astrophys & Geophys, 19c,Allee 6 Aout, B-4000 Liege, Belgium.;CRAAG, Route Observ,BP 63 Bouzareah, Algiers 16340, Algeria..
    Dapergolas, A.
    Natl Observ Athens, Athens 15236, Greece..
    David, P.
    UPMC Univ Paris 06, PSL Res Univ, IMCCE, Observ Paris,CNRS,Sorbonne Univ,Univ Lille, 77 Av Denfert Rochereau, F-75014 Paris, France..
    David, M.
    Univ Antwerp, Onderzoeksgrp Toegepaste Wiskunde, Middelheimlaan 1, B-2020 Antwerp, Belgium..
    De Cat, P.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    de Felice, F.
    Univ Padua, Dept Phys & Astron, Via Marzolo 8, I-35131 Padua, Italy..
    de laverny, P.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    De Luise, F.
    Osservatorio Astron Teramo, INAF, Via Mentore Maggini, I-64100 Teramo, Italy..
    De March, R.
    ALTEC Spa, Corso Marche 79, I-10146 Turin, Italy..
    de Martino, D.
    Osserv Astron Capodimonte, INAF, Via Moiariello 16, I-80131 Naples, Italy..
    de Souza, R.
    Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao,1226 Cidade Univ, BR-05508900 Sao Paulo, SP, Brazil..
    Debosscher, J.
    Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium..
    del Pozo, E.
    ESA ESAC, Aurora Technol, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Delbo, M.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Delgado, A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Delgado, H. E.
    UNED, Dept Inteligencia Artificial, C Juan del Rosal 16, Madrid 28040, Spain..
    Di Matteo, P.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Diakite, S.
    Univ Bourgogne Franche Comte, OSU THETA Franche Comte Bourgogne, CNRS, Inst UTINAM UMR6213, F-25000 Besancon, France..
    Distefano, E.
    Osserv Astrofis Catania, INAF, Via S Sofia 78, I-95123 Catania, Italy..
    Dolding, C.
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England..
    Dos Anjos, S.
    Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao,1226 Cidade Univ, BR-05508900 Sao Paulo, SP, Brazil..
    Drazinos, P.
    Univ Athens, Dept Astrophys Astron & Mech, Athens 15783, Greece..
    Duran, J.
    ESA ESAC, Isdefe, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Dzigan, Y.
    Tel Aviv Univ, Dept Geosci, IL-6997801 Tel Aviv, Israel.;Univ Amsterdam, Astron Inst Anton Pannekoek, POB 94249, NL-1090 GE Amsterdam, Netherlands..
    Edvardsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Enke, H.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Evans, N. W.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Bontemps, G. Eynard
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Fabre, C.
    CNES Ctr Spatial Toulouse, ATOS, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Fabrizio, M.
    ASI Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy.;Osservatorio Astron Teramo, INAF, Via Mentore Maggini, I-64100 Teramo, Italy..
    Faigler, S.
    Tel Aviv Univ, Sch Phys & Astron, IL-6997801 Tel Aviv, Israel..
    Falcao, A. J.
    UNINOVA CTS, Campus FCT UNL, P-2829516 Caparica, Portugal..
    Casas, M. Farras
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Federici, L.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Fedorets, G.
    Univ Helsinki, Dept Phys, POB 64, FIN-00014 Helsinki, Finland..
    Fernandez-Hernandez, J.
    Serco Gest Negocios ESA ESAC, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Fernique, P.
    Univ Strasbourg, Observ Astron Strasbourg, CNRS, UMR 7550, 11 Rue Univ, F-67000 Strasbourg, France..
    Fienga, A.
    Univ Nice Sophia Antipolis, Lab Geoazur, UMR 7329, CNRS,Observ Cote dAzur, 250 Rue A Einstein, F-06560 Valbonne, France..
    Figueras, F.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Filippi, F.
    ALTEC Spa, Corso Marche 79, I-10146 Turin, Italy..
    Findeisen, K.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Fonti, A.
    ALTEC Spa, Corso Marche 79, I-10146 Turin, Italy..
    Fouesneau, M.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany..
    Fraile, E.
    ESA ESAC, RHEA, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Fraser, M.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Fuchs, J.
    Acad Sci Czech Republic, Astron Inst, Fricova 298, Ondrejov 25165, Czech Republic..
    Gai, M.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Galleti, S.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Galluccio, L.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Garabato, D.
    Univ A Coruna, Fac Informat, Campus Elvina S-N, La Coruna 15071, Spain..
    Garcia-Sedano, F.
    UNED, Dept Inteligencia Artificial, C Juan del Rosal 16, Madrid 28040, Spain..
    Garofalo, A.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Garralda, N.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Gavras, P.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France.;Natl Observ Athens, Athens 15236, Greece.;Univ Athens, Dept Astrophys Astron & Mech, Athens 15783, Greece..
    Gerssen, J.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Geyer, R.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany..
    Gilmore, G.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Girona, S.
    Barcelona Supercomp Ctr, Centro Nacl Supercomp, C Jordi Girona 29,Ed Nexus 2, Barcelona 08034, Spain..
    Giuffrida, G.
    ASI Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy..
    Gomes, M.
    Univ Lisbon, CENTRA, FCUL, Edif C8, P-1749016 Lisbon, Portugal..
    Gonzalez-Marcos, A.
    Univ La Rioja, Dept Mech Engn, C San Jose de Calasanz 31, Logrono 26004, La Rioja, Spain..
    Gonzalez-Nunez, J.
    Serco Gest Negocios ESA ESAC, Camino Bajo del Castillo S-N, Madrid 28692, Spain.;Univ Vigo, ETSE Telecomunicac, Campus Lagoas Marcosende, Vigo 36310, Galicia, Spain..
    Gonzalez-Vidal, J. J.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Granvik, M.
    Univ Helsinki, Dept Phys, POB 64, FIN-00014 Helsinki, Finland..
    Guerrier, A.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Guillout, P.
    Univ Strasbourg, Observ Astron Strasbourg, CNRS, UMR 7550, 11 Rue Univ, F-67000 Strasbourg, France..
    Guiraud, J.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Gurpide, A.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Gutierrez-Sanchez, R.
    Telespazio Vega UK Ltd, ESA ESAC, Camino Bajo del Castillo, Madrid 28692, Spain..
    Guy, L. P.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Haigron, R.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Hatzidimitriou, D.
    Univ Athens, Dept Astrophys Astron & Mech, Athens 15783, Greece..
    Haywood, M.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Helmi, A.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands..
    Hobbs, D.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Hofmann, W.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Holl, B.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland..
    Holland, G.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Hunt, J. A. S.
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England..
    Hypki, A.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands..
    Icardi, V.
    ALTEC Spa, Corso Marche 79, I-10146 Turin, Italy..
    Irwin, M.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    de Fombelle, G. Jevardat
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Jofre, P.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.;Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Jonker, P. G.
    Radboud Univ Nijmegen, IMAPP, Dept Astrophys, POB 9010, NL-6500 GL Nijmegen, Netherlands.;SRON Netherlands Inst Space Res, SRON, Sorbonnelaan 2, NL-3584 CA Utrecht, Netherlands..
    Jorissen, A.
    Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226,Blvd Triomphe, B-1050 Brussels, Belgium..
    Julbe, F.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Karampelas, A.
    Natl Observ Athens, Athens 15236, Greece.;Univ Athens, Dept Astrophys Astron & Mech, Athens 15783, Greece..
    Kochoska, A.
    Univ Ljubljana, Fac Math & Phys, Jadranska Ulica 19, Ljubljana 1000, Slovenia..
    Kohley, R.
    European Space Astron Ctr ESA ESAC, Camino Bajo dell Castillo S-N, Madrid 28692, Spain..
    Kolenberg, K.
    Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium.;Univ Antwerp, Dept Phys, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.;Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA..
    Kontizas, E.
    Natl Observ Athens, Athens 15236, Greece..
    Koposov, S. E.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Kordopatis, G.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France.;Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Koubsky, P.
    Acad Sci Czech Republic, Astron Inst, Fricova 298, Ondrejov 25165, Czech Republic..
    Krone-Martins, A.
    Univ Lisbon, CENTRA, FCUL, Edif C8, P-1749016 Lisbon, Portugal..
    Kudryashova, M.
    UPMC Univ Paris 06, PSL Res Univ, IMCCE, Observ Paris,CNRS,Sorbonne Univ,Univ Lille, 77 Av Denfert Rochereau, F-75014 Paris, France..
    Kull, I.
    Tel Aviv Univ, Sch Phys & Astron, IL-6997801 Tel Aviv, Israel..
    Bachchan, R. K.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Lacoste-Seris, F.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Lanza, A. F.
    Osserv Astrofis Catania, INAF, Via S Sofia 78, I-95123 Catania, Italy..
    Lavigne, J. -B
    Le Poncin-Lafitte, C.
    UPMC Univ Paris 06, PSL Res Univ, CNRS, SYRTE,Observ Paris,Sorbonne Univ,LNE, 61 Ave Observ, F-75014 Paris, France..
    Lebreton, Y.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France.;Univ Rennes 1, Inst Phys Rennes, F-35042 Rennes, France..
    Lebzelter, T.
    Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria..
    Leccia, S.
    Osserv Astron Capodimonte, INAF, Via Moiariello 16, I-80131 Naples, Italy..
    Leclerc, N.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Lecoeur-Taibi, I.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Lemaitre, V.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Lenhardt, H.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Leroux, F.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Liao, S.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy.;Chinese Acad Sci, Shanghai Astron Observ, 80 Nandan Rd, Shanghai 200030, Peoples R China..
    Licata, E.
    EURIX Srl, Via Carcano 26, I-10153 Turin, Italy..
    Lindstrom, H. E. P.
    Univ Copenhagen, Niels Bohr Inst, Juliane Maries Vej 30, DK-2100 Copenhagen O, Denmark.;CSC Danmark AS, Retortvej 8, DK-2500 Valby, Denmark..
    Lister, T. A.
    Las Cumbres Observ Global Telescope Network Inc, 6740 Cortona Dr,Suite 102, Goleta, CA 93117 USA..
    Livanou, E.
    Univ Athens, Dept Astrophys Astron & Mech, Athens 15783, Greece..
    Lobel, A.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    Loeffler, W.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Lopez, M.
    ESA ESAC, Ctr Astrobiol CSIC INTA, Dept Astrofis, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Lorenz, D.
    Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria..
    MacDonald, I.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Fernandes, T. Magalhacs
    UNINOVA CTS, Campus FCT UNL, P-2829516 Caparica, Portugal..
    Managau, S.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Mann, R. G.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Mantelet, G.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Marchal, O.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Marchant, J. M.
    Liverpool John Moores Univ, Astrophys Res Inst, Liverpool L3 5RF, Merseyside, England..
    Marconi, M.
    Osserv Astron Capodimonte, INAF, Via Moiariello 16, I-80131 Naples, Italy..
    Marinoni, S.
    ASI Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy.;Osserv Astron Roma, INAF, Via Frascati 33, I-00078 Rome, Italy..
    Marrese, P. M.
    ASI Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy.;Osserv Astron Roma, INAF, Via Frascati 33, I-00078 Rome, Italy..
    Marschalko, G.
    Hungarian Acad Sci, Res Ctr Astron & Earth Sci, Konkoly Observ, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary.;Univ Szeged, Baja Observ, Szegedi Ut 3-70, H-6500 Baja, Hungary..
    Marshall, D. J.
    Univ Paris Diderot, CEA Saclay, CEA DSM CNRS, IRFU,Serv Astrophys,Lab AIM, Bat 709, F-91191 Gif Sur Yvette, France..
    Martin-Fleitas, J. M.
    ESA ESAC, Aurora Technol, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Martino, M.
    ALTEC Spa, Corso Marche 79, I-10146 Turin, Italy..
    Mary, N.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Matijevic, G.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Mazeh, T.
    Tel Aviv Univ, Sch Phys & Astron, IL-6997801 Tel Aviv, Israel..
    McMillan, P. J.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Messina, S.
    Osserv Astrofis Catania, INAF, Via S Sofia 78, I-95123 Catania, Italy..
    Michalik, D.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Millar, N. R.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Miranda, B. M. H.
    Univ Lisbon, CENTRA, FCUL, Edif C8, P-1749016 Lisbon, Portugal..
    Molina, D.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Molinaro, R.
    Osserv Astron Capodimonte, INAF, Via Moiariello 16, I-80131 Naples, Italy..
    Molinaro, M.
    Osserv Astron Trieste, INAF, Via GB Tiepolo 11, I-34143 Trieste, Italy..
    Molnar, L.
    Hungarian Acad Sci, Res Ctr Astron & Earth Sci, Konkoly Observ, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary..
    Moniez, M.
    Univ Paris Saclay, CNRS IN2P3, Univ Paris Sud, Lab Accelerateur Lineaire, F-91898 Orsay, France..
    Montegriffo, P.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Mor, R.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Mora, A.
    ESA ESAC, Aurora Technol, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Morbidelli, R.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Morel, T.
    Univ Liege, Inst Astrophys & Geophys, 19c,Allee 6 Aout, B-4000 Liege, Belgium..
    Morgenthaler, S.
    Ecole Polytech Fed Lausanne, SB MATHAA STAP, MA B1 473,Batiment MA,Stn 8, CH-1015 Lausanne, Switzerland..
    Morris, D.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Mulone, A. F.
    ALTEC Spa, Corso Marche 79, I-10146 Turin, Italy..
    Muraveva, T.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Musella, I.
    Osserv Astron Capodimonte, INAF, Via Moiariello 16, I-80131 Naples, Italy..
    Narbonne, J.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Nelemans, G.
    Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium.;Radboud Univ Nijmegen, IMAPP, Dept Astrophys, POB 9010, NL-6500 GL Nijmegen, Netherlands..
    Nicastro, L.
    INAF IASF Bologna, Via P Gobetti 101, I-40129 Bologna, Italy..
    Noval, L.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Ordenovic, C.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Ordieres-Mere, J.
    Tech Univ Madrid, Jose Gutierrez Abascal 2, Madrid 28006, Spain..
    Osborne, P.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Pagani, C.
    Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England..
    Pagano, I.
    Osserv Astrofis Catania, INAF, Via S Sofia 78, I-95123 Catania, Italy..
    Pailler, F.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Palacin, H.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Palaversa, L.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland..
    Parsons, P.
    Telespazio Vega UK Ltd, ESA ESAC, Camino Bajo del Castillo, Madrid 28692, Spain..
    Pecoraro, M.
    EURIX Srl, Via Carcano 26, I-10153 Turin, Italy..
    Pedrosa, R.
    CNES Ctr Spatial Toulouse, EQUERT Int, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Pentikainen, H.
    Univ Helsinki, Dept Phys, POB 64, FIN-00014 Helsinki, Finland..
    Pichon, B.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Piersimoni, A. M.
    Osservatorio Astron Teramo, INAF, Via Mentore Maggini, I-64100 Teramo, Italy..
    Pincau, F. -X
    Plachy, E.
    Hungarian Acad Sci, Res Ctr Astron & Earth Sci, Konkoly Observ, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary..
    Plum, G.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Poujoulet, E.
    CNES Ctr Spatial Toulouse, AKKA, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Prsa, A.
    Villanova Univ, Dept Astrophys & Planetary Sci, 800 E Lancaster Ave, Villanova, PA 19085 USA..
    Pulone, L.
    Osserv Astron Roma, INAF, Via Frascati 33, I-00078 Rome, Italy..
    Ragaini, S.
    Osservatorio Astron Bologna, INAF, Via Ranzani 1, I-40127 Bologna, Italy..
    Rago, S.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Rambaux, N.
    UPMC Univ Paris 06, PSL Res Univ, IMCCE, Observ Paris,CNRS,Sorbonne Univ,Univ Lille, 77 Av Denfert Rochereau, F-75014 Paris, France..
    Ramos-Lerate, M.
    ESA ESAC, Vitrociset Belgium, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Ranalli, P.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Rauw, G.
    Univ Liege, Inst Astrophys & Geophys, 19c,Allee 6 Aout, B-4000 Liege, Belgium..
    Read, A.
    Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England..
    Regibo, S.
    Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium..
    Reyle, C.
    Univ Bourgogne Franche Comte, OSU THETA Franche Comte Bourgogne, CNRS, Inst UTINAM UMR6213, F-25000 Besancon, France..
    Ribeiro, R. A.
    UNINOVA CTS, Campus FCT UNL, P-2829516 Caparica, Portugal..
    Rimoldini, L.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Ripepi, V.
    Osserv Astron Capodimonte, INAF, Via Moiariello 16, I-80131 Naples, Italy..
    Riva, A.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Rixon, G.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Roelens, M.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland..
    Romero-Gomez, M.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Rowell, N.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Royer, F.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Ruiz-Dern, L.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Sadowski, G.
    Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226,Blvd Triomphe, B-1050 Brussels, Belgium..
    Selles, T. Sagrista
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Sahlmann, J.
    European Space Astron Ctr ESA ESAC, Camino Bajo dell Castillo S-N, Madrid 28692, Spain..
    Salgado, J.
    ESA ESAC, Isdefe, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Salguero, E.
    ESA ESAC, Isdefe, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Sarasso, M.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Savietto, H.
    Fork Res, Rua Cruzado Osberno,Lt 1,9 Esq, Lisbon, Portugal..
    Schultheis, M.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Sciacca, E.
    Osserv Astrofis Catania, INAF, Via S Sofia 78, I-95123 Catania, Italy..
    Segol, M.
    CNES Ctr Spatial Toulouse, APAVE SUDEUROPE SAS, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Segovia, J. C.
    Serco Gest Negocios ESA ESAC, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Segransan, D.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland..
    Shih, I. -C
    Smareglia, R.
    Osserv Astron Trieste, INAF, Via GB Tiepolo 11, I-34143 Trieste, Italy..
    Smart, R. L.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Solano, E.
    ESA ESAC, Ctr Astrobiol CSIC INTA, Dept Astrofis, Camino Bajo del Castillo S-N, Madrid 28692, Spain.;Spanish Virtual Observ, Granada, Spain..
    Solitro, F.
    ALTEC Spa, Corso Marche 79, I-10146 Turin, Italy..
    Sordo, R.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Nieto, S. Soria
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Souchay, J.
    UPMC Univ Paris 06, PSL Res Univ, CNRS, SYRTE,Observ Paris,Sorbonne Univ,LNE, 61 Ave Observ, F-75014 Paris, France..
    Spagna, A.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Spoto, F.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Stampa, U.
    Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg, Germany..
    Steele, I. A.
    Liverpool John Moores Univ, Astrophys Res Inst, Liverpool L3 5RF, Merseyside, England..
    Steidelmueller, H.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany..
    Stephenson, C. A.
    Telespazio Vega UK Ltd, ESA ESAC, Camino Bajo del Castillo, Madrid 28692, Spain..
    Stoev, H.
    INAF, Fdn Galileo Galilei, Rambla Jose Ana Fernandez Perez 7, Brena Baja 38712, Santa Cruz De T, Spain..
    Suess, F. F.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Suveges, M.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Surdej, J.
    Univ Liege, Inst Astrophys & Geophys, 19c,Allee 6 Aout, B-4000 Liege, Belgium..
    Szabados, L.
    Hungarian Acad Sci, Res Ctr Astron & Earth Sci, Konkoly Observ, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary..
    Szegedi-Elek, E.
    Hungarian Acad Sci, Res Ctr Astron & Earth Sci, Konkoly Observ, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary..
    Tapiador, D.
    ESA ESAC, INSA, Camino Bajo del Castillo S-N, Madrid 28692, Spain.;Univ Complutense Madrid, Dept Arquitectura Comp & Automat, Fac Informat, C Prof Jose Garcia Santesmases S-N, E-28040 Madrid, Spain..
    Taris, F.
    UPMC Univ Paris 06, PSL Res Univ, CNRS, SYRTE,Observ Paris,Sorbonne Univ,LNE, 61 Ave Observ, F-75014 Paris, France..
    Tauran, G.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Taylor, M. B.
    Univ Bristol, HH Wills Phys Lab, Tyndall Ave, Bristol BS8 1TL, Avon, England..
    Teixeira, R.
    Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao,1226 Cidade Univ, BR-05508900 Sao Paulo, SP, Brazil..
    Terrett, D.
    Rutherford Appleton Lab, STFC, Didcot OX11 0QX, Oxon, England..
    Tingley, B.
    Aarhus Univ, Stellar Astrophys Ctr, Dept Phys & Astron, 120 Ny Munkegade,Bldg 1520, DK-8000 Aarhus C, Denmark..
    Trager, S. C.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands..
    Turon, C.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Ulla, A.
    Univ Vigo, Dept Appl Phys, Vigo 36310, Spain..
    Utrilla, E.
    ESA ESAC, Aurora Technol, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Valentini, G.
    Osservatorio Astron Teramo, INAF, Via Mentore Maggini, I-64100 Teramo, Italy..
    van Elteren, A.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands..
    Van Hemelryck, E.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    van Leeuwen, M.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Varadi, M.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.;Hungarian Acad Sci, Res Ctr Astron & Earth Sci, Konkoly Observ, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary..
    Vecchiato, A.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Veljanoski, J.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands..
    Via, T.
    Univ Catalunya, Consorci Serv, C Gran Capita 2-4 3rd Floor, Barcelona 08034, Spain..
    Vicente, D.
    Barcelona Supercomp Ctr, Centro Nacl Supercomp, C Jordi Girona 29,Ed Nexus 2, Barcelona 08034, Spain..
    Vogt, S.
    ESA ESTEC, HE Space Operat BV, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands..
    Voss, H.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Votruba, V.
    Acad Sci Czech Republic, Astron Inst, Fricova 298, Ondrejov 25165, Czech Republic..
    Voutsinas, S.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Walmsley, G.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Weiler, M.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Weingrill, K.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Wevers, T.
    Radboud Univ Nijmegen, IMAPP, Dept Astrophys, POB 9010, NL-6500 GL Nijmegen, Netherlands..
    Wyrzykowski, L.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.;Univ Warsaw Observ, Al Ujazdowskie 4, PL-00478 Warsaw, Poland..
    Yoldas, A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Zerjal, M.
    Univ Ljubljana, Fac Math & Phys, Jadranska Ulica 19, Ljubljana 1000, Slovenia..
    Zucker, S.
    Tel Aviv Univ, Dept Geosci, IL-6997801 Tel Aviv, Israel..
    Zurbach, C.
    Univ Montpellier, Lab Univers & Particules Montpellier, Pl Eugene Bataillon,CC72, F-34095 Montpellier 05, France..
    Zwitter, T.
    Univ Ljubljana, Fac Math & Phys, Jadranska Ulica 19, Ljubljana 1000, Slovenia..
    Alecu, A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Allen, M.
    European Space Res & Technol Ctr ESA ESTEC, Directorate Sci, Sci Support Off, Keplerlaan 1, NL-2201AZ Noordwijk, Netherlands..
    Prieto, C. Allende
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England.;Inst Astrofis Canarias, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, Tenerife 38206, Spain..
    Amorim, A.
    Univ Lisbon, CENTRA, FCUL, Edif C8, P-1749016 Lisbon, Portugal..
    Anglada-Escude, G.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Arsenijevic, V.
    Univ Lisbon, CENTRA, FCUL, Edif C8, P-1749016 Lisbon, Portugal..
    Azaz, S.
    European Space Res & Technol Ctr ESA ESTEC, Directorate Sci, Sci Support Off, Keplerlaan 1, NL-2201AZ Noordwijk, Netherlands..
    Balm, P.
    Telespazio Vega UK Ltd, ESA ESAC, Camino Bajo del Castillo, Madrid 28692, Spain..
    Beck, M.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Bernstein, H. -H
    Bigot, L.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Bijaoui, A.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Blasco, C.
    ESA ESTEC, RHEA, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands..
    Bonfigli, M.
    Osservatorio Astron Teramo, INAF, Via Mentore Maggini, I-64100 Teramo, Italy..
    Bono, G.
    Osserv Astron Roma, INAF, Via Frascati 33, I-00078 Rome, Italy..
    Boudreault, S.
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England.;Max Planck Inst Solar Syst Res, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Bressan, A.
    SISSA, Via Bonomea 265, I-34136 Trieste, Italy..
    Brown, S.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Brunet, P. -M
    Bunclark, P.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Buonanno, R.
    Osserv Astron Roma, INAF, Via Frascati 33, I-00078 Rome, Italy..
    Butkevich, A. G.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany..
    Carret, C.
    CNES Ctr Spatial Toulouse, EQUERT Int, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Carrion, C.
    UNED, Dept Inteligencia Artificial, C Juan del Rosal 16, Madrid 28040, Spain..
    Chemin, L.
    Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France.;Minist Ciencia Tecnol, Inst Nacl Pesquisas Espaciais, Ave Astronautas 1758, BR-12227010 Sao Jose Dos Campos, SP, Brazil..
    Chereau, F.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Corcione, L.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Darmigny, E.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    de Boer, K. S.
    Univ Bonn, Argelander Inst Astron, Hugel 71, D-53121 Bonn, Germany..
    de Teodoro, P.
    Serco Gest Negocios ESA ESAC, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    de Zeeuw, P. T.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands.;European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Delle Luche, C.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France.;CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Domingues, C. D.
    Univ Lisbon, Lab Opt Lasers & Syst, Fac Sci, Campus Lumiar,Estr Paco Lumiar 22, P-1649038 Lisbon, Portugal..
    Dubath, P.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Fodor, F.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Frezouls, B.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Fries, A.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Fustes, D.
    Univ A Coruna, Fac Informat, Campus Elvina S-N, La Coruna 15071, Spain..
    Fyfe, D.
    Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England..
    Gallardo, E.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Gallegos, J.
    Serco Gest Negocios ESA ESAC, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Gardiol, D.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Gebran, M.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain.;Notre Dame Univ, Dept Phys & Astron, POB 72, Zouk Mikael, Lebanon..
    Gomboc, A.
    Univ Ljubljana, Fac Math & Phys, Jadranska Ulica 19, Ljubljana 1000, Slovenia.;Univ Nova Gorica, Vipavska 13, Nova Gorica 5000, Slovenia..
    Gomez, A.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Grux, E.
    Univ Bourgogne Franche Comte, OSU THETA Franche Comte Bourgogne, CNRS, Inst UTINAM UMR6213, F-25000 Besancon, France..
    Gueguen, A.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France.;OPINAS, Max Planck Inst Extraterr Phys, Giessenbachstr, D-85741 Garching, Germany..
    Heyrovsky, A.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Hoar, J.
    European Space Astron Ctr ESA ESAC, Camino Bajo dell Castillo S-N, Madrid 28692, Spain..
    Iannicola, G.
    Osserv Astron Roma, INAF, Via Frascati 33, I-00078 Rome, Italy..
    Parache, Y. Isasi
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Janotto, A. -M
    Joliet, E.
    ESA ESAC, HE Space Operat BV, Camino Bajo del Castillo S-N, Madrid 28692, Spain.;CALTECH, NASA IPAC Infrared Sci Arch, Mail Code 100-22,770 South Wilson Ave, Pasadena, CA 91125 USA..
    Jonckheere, A.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    Keil, R.
    Univ Bremen, Ctr Appl Space Technol & Micrograv ZARM, Fallturm 1, D-28359 Bremen, Germany.;ESA ESOC, RHEA Syst, Robert Bosch Str 5, D-64293 Darmstadt, Germany..
    Kim, D. -W
    Klagyivik, P.
    Hungarian Acad Sci, Res Ctr Astron & Earth Sci, Konkoly Observ, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary..
    Klar, J.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Knude, J.
    Univ Copenhagen, Niels Bohr Inst, Juliane Maries Vej 30, DK-2100 Copenhagen O, Denmark..
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Kolka, I.
    Tartu Observ, EE-61602 Toravere, Estonia..
    Kos, J.
    Univ Ljubljana, Fac Math & Phys, Jadranska Ulica 19, Ljubljana 1000, Slovenia.;Univ Sydney, Sch Phys A28, Sydney Inst Astron, Sydney, NSW 2006, Australia..
    Kutka, A.
    Acad Sci Czech Republic, Astron Inst, Fricova 298, Ondrejov 25165, Czech Republic.;Slovak Org Space Activ, Zamocka 18, Bratislava 85101, Slovakia..
    Lainey, V.
    UPMC Univ Paris 06, PSL Res Univ, IMCCE, Observ Paris,CNRS,Sorbonne Univ,Univ Lille, 77 Av Denfert Rochereau, F-75014 Paris, France..
    LeBouquin, D.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Liu, C.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.;Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China..
    Loreggia, D.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Makarov, V. V.
    US Naval Observ, Astrometry Dept, 3450 Massachusetts Ave NW, Washington, DC 20392 USA..
    Marseille, M. G.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Martayan, C.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium.;European Southern Observ, Alonso de Cordova 3107, Casilla 19001, Santiago De Chi, Chile..
    Martinez-Rubi, O.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Massart, B.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France.;CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.;Airbus Def & Space SAS, 31 Rue Cosmonautes, F-31402 Toulouse 4, France..
    Meynadier, F.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France.;UPMC Univ Paris 06, PSL Res Univ, CNRS, SYRTE,Observ Paris,Sorbonne Univ,LNE, 61 Ave Observ, F-75014 Paris, France..
    Mignot, S.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Munari, U.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Nguyen, A. -T
    Nordlander, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Ocvirk, P.
    Univ Strasbourg, Observ Astron Strasbourg, CNRS, UMR 7550, 11 Rue Univ, F-67000 Strasbourg, France.;Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    O'Flaherty, K. S.
    ESA ESTEC, EJR Quartz BV, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands..
    Sanz, A. Olias
    ESA ESAC, Server Labs, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Ortiz, P.
    Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England..
    Osorio, J.
    Univ Porto, Fac Ciencias, Dept Matemat, Rua Campo Alegre 687, P-4169007 Oporto, Portugal..
    Oszkiewicz, D.
    Univ Helsinki, Dept Phys, POB 64, FIN-00014 Helsinki, Finland.;Adam Mickiewicz Univ, Fac Phys, Astron Observ Inst, Ul Sloneczna 36, PL-60286 Poznan, Poland..
    Ouzounis, A.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Palmer, M.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Park, P.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland..
    Pasquato, E.
    Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226,Blvd Triomphe, B-1050 Brussels, Belgium..
    Peltzer, C.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Peralta, J.
    Peturaud, F.
    Univ Paris Diderot, PSL Res Univ, CNRS, GEPI,Observ Paris,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Pieniluoma, T.
    Univ Helsinki, Dept Phys, POB 64, FIN-00014 Helsinki, Finland..
    Pigozzi, E.
    ALTEC Spa, Corso Marche 79, I-10146 Turin, Italy..
    Poels, J.
    Univ Liege, Inst Astrophys & Geophys, 19c,Allee 6 Aout, B-4000 Liege, Belgium..
    Prat, G.
    CNES Ctr Spatial Toulouse, CS Syst Informat, 18 Ave Edouard Belin, F-31401 Toulouse 9, France..
    Prod'homme, T.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands.;European Space Res & Technol Ctr ESA ESTEC, Directorate Sci, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands..
    Raison, F.
    OPINAS, Max Planck Inst Extraterr Phys, Giessenbachstr, D-85741 Garching, Germany.;ESA ESAC, Praesepe BV, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Rebordao, J. M.
    Univ Lisbon, Lab Opt Lasers & Syst, Fac Sci, Campus Lumiar,Estr Paco Lumiar 22, P-1649038 Lisbon, Portugal..
    Risquez, D.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands..
    Rocca-Volmerange, B.
    UPMC, Sorbonne Univ, F-75014 Paris, France.;Inst Astrophys Paris, CNRS, UMR7095, F-75014 Paris, France..
    Rosen, S.
    Univ Coll London, Mullard Space Sci Lab, Surrey RH5 6NT, England.;Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England..
    Ruiz-Fuertes, M. I.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland..
    Russo, F.
    Osserv Astron Torino, INAF, Via Osservatorio 20, I-10025 Pino Torinese, TO, Italy..
    Sembay, S.
    Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England..
    Vizcaino, I. Serraller
    ESA ESAC, GMV, Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Short, A.
    European Space Res & Technol Ctr ESA ESTEC, Directorate Sci, Sci Support Off, Keplerlaan 1, NL-2201AZ Noordwijk, Netherlands..
    Siebert, A.
    Univ Strasbourg, Observ Astron Strasbourg, CNRS, UMR 7550, 11 Rue Univ, F-67000 Strasbourg, France.;Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Silva, H.
    UNINOVA CTS, Campus FCT UNL, P-2829516 Caparica, Portugal..
    Sinachopoulos, D.
    Natl Observ Athens, Athens 15236, Greece..
    Slezak, E.
    Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote dAzur, CNRS, CS 34229, F-06304 Nice, France..
    Soffel, M.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany..
    Sosnowska, D.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland..
    Straizys, V.
    Vilnius Univ, Inst Theoret Phys & Astron, Sauletekio Al 3, LT-10222 Vilnius, Lithuania..
    ter Linden, M.
    ESA ESAC, HE Space Operat BV, Camino Bajo del Castillo S-N, Madrid 28692, Spain.;S&T Corp, POB 608, NL-2600 AP Delft, Netherlands..
    Terrell, D.
    Southwest Res Inst SwRI, Dept Space Studies, 1050 Walnut St,Suite 300, Boulder, CO 80302 USA..
    Theil, S.
    Inst Space Syst, Deutsch Zentrum Luft & Raumfahrt, Fallturm 1, D-28359 Bremen, Germany..
    Tiede, C.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.;Univ Appl Sci Munich, Karlstr 6, D-80333 Munich, Germany..
    Troisi, L.
    ASI Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy.;Univ Roma Tor Vergata, Dipartimento Fis, Via Ric Sci 1, I-00133 Rome, Italy..
    Tsalmantza, P.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany..
    Tur, D.
    Univ Catalunya, Consorci Serv, C Gran Capita 2-4 3rd Floor, Barcelona 08034, Spain..
    Vaccari, M.
    Univ Western Cape, Dept Phys & Astron, Robert Sobukwe Rd, ZA-7535 Cape Town, South Africa.;INAF Ist Radioastron, Via Gobetti 101, I-40129 Bologna, Italy..
    Vachier, F.
    UPMC Univ Paris 06, PSL Res Univ, IMCCE, Observ Paris,CNRS,Sorbonne Univ,Univ Lille, 77 Av Denfert Rochereau, F-75014 Paris, France..
    Valles, P.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti Franques 1, E-08028 Barcelona, Spain..
    Van Hamme, W.
    Florida Int Univ, Dept Phys, 11200 SW 8th St, Miami, FL 33199 USA..
    Veltz, L.
    Univ Paris XI, CNRS, Inst Astrophys Spatiale, UMR 8617, Batiment 121, F-91405 Orsay, France.;Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Virtanen, J.
    Univ Helsinki, Dept Phys, POB 64, FIN-00014 Helsinki, Finland.;Finnish Geospatial Res Inst FGI, Geodeetinrinne 2, Masala 02430, Finland..
    Wallut, J. -M
    Wichmann, R.
    Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg, Germany..
    Wilkinson, M. I.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.;Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England..
    Ziaeepour, H.
    Univ Bourgogne Franche Comte, OSU THETA Franche Comte Bourgogne, CNRS, Inst UTINAM UMR6213, F-25000 Besancon, France..
    Zschocke, S.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany..
    Gaia Data Release 1 Summary of the astrometric, photometric, and survey properties2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 595, A2Article in journal (Refereed)
    Abstract [en]

    Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues - a realisation of the Tycho-Gaia Astrometric Solution (TGAS) - and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of similar to 3000 Cepheid and RR Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr(-1) for the proper motions. A systematic component of similar to 0.3 mas should be added to the parallax uncertainties. For the subset of similar to 94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr(-1). For the secondary astrometric data set, the typical uncertainty of the positions is similar to 10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to similar to 0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data.

  • 40. Caffau, E.
    et al.
    Ludwig, H. -G.
    Steffen, M.
    Ayres, T. R.
    Bonifacio, P.
    Cayrel, R.
    Freytag, B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Plez, B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    The photospheric solar oxygen project - I. Abundance analysis of atomic lines and influence of atmospheric models2008In: Astronomy and Astrophysics, ISSN 0004-6361, Vol. 488, no 3, 1031-1046 p.Article in journal (Refereed)
    Abstract [en]

    Context. The solar oxygen abundance has undergone a major downward revision in the past decade, the most noticeable one being the update including 3D hydrodynamical simulations to model the solar photosphere. Up to now, such an analysis has only been carried out by one group using one radiation-hydrodynamics code. Aims. We investigate the photospheric oxygen abundance considering lines from atomic transitions. We also consider the relationship between the solar model used and the resulting solar oxygen abundance, to understand whether the downward abundance revision is specifically related to 3D hydrodynamical effects. Methods. We performed a new determination of the solar photospheric oxygen abundance by analysing different high-resolution high signal-to-noise ratio atlases of the solar flux and disc-centre intensity, making use of the latest generation of CO5BOLD 3D solar model atmospheres. Results. We find 8.73 <= log (N-O/N-H) + 12 <= 8.79. The lower and upper values represent extreme assumptions on the role of collisional excitation and ionisation by neutral hydrogen for the NLTE level populations of neutral oxygen. The error of our analysis is +/- (0.04 +/- 0.03) dex, the last being related to NLTE corrections, the first error to any other effect. The 3D "granulation effects" do not play a decisive role in lowering the oxygen abundance. Conclusions. Our recommended value is log (N-O/N-H) = 8.76 +/- 0.07, considering our present ignorance of the role of collisions with hydrogen atoms on the NLTE level populations of oxygen. The reasons for lower O abundances in the past are identified as (1) the lower equivalent widths adopted and (2) the choice of neglecting collisions with hydrogen atoms in the statistical equilibrium calculations for oxygen.

  • 41.
    Calvo, F.
    et al.
    Ist Ric Solari Locarno IRSOL, Via Patocchi 57 Prato Pernice, CH-6605 Locarno, Switzerland.;Univ Geneva, Observ Geneva, Ch Maillettes 51, CH-1290 Sauverny, Switzerland..
    Steiner, O.
    Ist Ric Solari Locarno IRSOL, Via Patocchi 57 Prato Pernice, CH-6605 Locarno, Switzerland.;Kiepenheuer Inst Sonnenphys, Schoneckstr 6, D-79104 Freiburg, Germany..
    Freytag, Bernd
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Non-magnetic photospheric bright points in 3D simulations of the solar atmosphere2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 596, A43Article in journal (Refereed)
    Abstract [en]

    Context. Small-scale bright features in the photosphere of the Sun, such as faculae or G-band bright points, appear in connection with small-scale magnetic flux concentrations. Aims. Here we report on a new class of photospheric bright points that are free of magnetic fields. So far, these are visible in numerical simulations only. We explore conditions required for their observational detection. Methods. Numerical radiation (magneto-) hydrodynamic simulations of the near-surface layers of the Sun were carried out. The magnetic field-free simulations show tiny bright points, reminiscent of magnetic bright points, only smaller. A simple toy model for these non-magnetic bright points (nMBPs) was established that serves as a base for the development of an algorithm for their automatic detection. Basic physical properties of 357 detected nMBPs were extracted and statistically evaluated. We produced synthetic intensity maps that mimic observations with various solar telescopes to obtain hints on their detectability. Results. The nMBPs of the simulations show a mean bolometric intensity contrast with respect to their intergranular surroundings of approximately 20%, a size of 60-80 km, and the isosurface of optical depth unity is at their location depressed by 80-100 km. They are caused by swirling downdrafts that provide, by means of the centripetal force, the necessary pressure gradient for the formation of a funnel of reduced mass density that reaches from the subsurface layers into the photosphere. Similar, frequently occurring funnels that do not reach into the photosphere, do not produce bright points. Conclusions. Non-magnetic bright points are the observable manifestation of vertically extending vortices (vortex tubes) in the photosphere. The resolving power of 4-m-class telescopes, such as the DKIST, is needed for an unambiguous detection of them.

  • 42. Chiavassa, A.
    et al.
    Freytag, Bernd
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Masseron, T.
    Plez, B.
    Radiative hydrodynamics simulations of red supergiant stars IV. Gray versus non-gray opacities2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 535, A22- p.Article in journal (Refereed)
    Abstract [en]

    Context. Red supergiants are massive evolved stars that contribute extensively to the chemical enrichment of our Galaxy. It has been shown that convection in those stars produces large granules that cause surface inhomogeneities and shock waves in the photosphere. The understanding of their dynamics is crucial for unveiling the unknown mass-loss mechanism, their chemical composition, and their stellar parameters.

    Aims. We present a new generation of red supergiant simulations with a more sophisticated opacity treatment performed with 3D radiative-hydrodynamics code CO5BOLD.

    Methods. In the code the coupled equations of compressible hydrodynamics and non-local radiation transport are solved in the presence of a spherical potential. The stellar core is replaced by a special spherical inner boundary condition, where the gravitational potential is smoothed and the energy production by fusion is mimicked by a simply producing heat corresponding to the stellar luminosity. All outer boundaries are transmitting for matter and light. The post-processing radiative transfer code OPTIM3D is used to extract spectroscopic and interferometric observables.

    Results. We show that if one relaxes the assumption of frequency-independent opacities, this leads to a steeper mean thermal gradient in the optical thin region that strongly affects the atomic strengths and the spectral energy distribution. Moreover, the weaker temperature fluctuations reduce the incertitude on the radius determination with interferometry. We show that 1D models of red supergiants must include a turbulent velocity that is calibrated on 3D simulations to obtain the effective surface gravity that mimics the effect of turbulent pressure on the stellar atmosphere. We provide an empirical calibration of the ad hoc micro- and macroturbulence parameters for 1D models using the 3D simulations: we find that there is no clear distinction between the different macroturbulent profiles needed in 1D models to fit 3D synthetic lines.

  • 43. Chiavassa, A.
    et al.
    Haubois, X.
    Young, J. S.
    Plez, B.
    Josselin, E.
    Perrin, G.
    Freytag, B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Radiative hydrodynamics simulations of red supergiant stars II. Simulations of convection on Betelgeuse match interferometric observations2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 515, A12- p.Article in journal (Refereed)
    Abstract [en]

    Context. The red supergiant (RSG) Betelgeuse is an irregular variable star. Convection may play an important role in understanding this variability. Interferometric observations can be interpreted using sophisticated simulations of stellar convection. Aims. We compare the visibility curves and closure phases obtained from our 3D simulation of RSG convection with CO5BOLD to various interferometric observations of Betelgeuse from the optical to the H band to characterize and measure the convection pattern on this star. Methods. We use a 3D radiative-hydrodynamics (RHD) simulation to compute intensity maps in different filters and thus derive interferometric observables using the post-processing radiative transfer code OPTIM3D. The synthetic visibility curves and closure phases are compared to observations. Results. We provide a robust detection of the granulation pattern on the surface of Betelgeuse in both the optical and the H band based on excellent fits to the observed visibility points and closure phases. We determine that the Betelgeuse surface in the H band is covered by small to medium scale (5-15 mas) convection-related surface structures and a large (approximate to 30 mas) convective cell. In this spectral region, H2O molecules are the main absorbers and contribute to both the small structures and the position of the first null of the visibility curve (i.e., the apparent stellar radius).

  • 44. Chiavassa, A.
    et al.
    Lacour, S.
    Millour, F.
    Driebe, T.
    Wittkowski, M.
    Plez, B.
    Thiebaut, E.
    Josselin, E.
    Freytag, B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Scholz, M.
    Haubois, X.
    VLTI/AMBER spectro-interferometric imaging of VX Sagittarii's inhomogenous outer atmosphere2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 511, A51- p.Article in journal (Refereed)
    Abstract [en]

    Aims. We aim to explore the photosphere of the very cool late-type star VX Sgr and in particular the characterization of molecular layers above the continuum forming photosphere. Methods. We obtained interferometric observations with the VLTI/AMBER interferometer using the fringe tracker FINITO in the spectral domain 1.45-2.50 mu m with a spectral resolution of approximate to 35 and baselines ranging from 15 to 88 m. We performed independent image reconstruction for different wavelength bins and fit the interferometric data with a geometrical toy model. We also compared the data to 1D dynamical models of Miras atmosphere and to 3D hydrodynamical simulations of red supergiant (RSG) and asymptotic giant branch (AGB) stars. Results. Reconstructed images and visibilities show a strong wavelength dependence. The H-band images display two bright spots whose positions are confirmed by the geometrical toy model. The inhomogeneities are qualitatively predicted by 3D simulations. At approximate to 2.00 mu m and in the region 2.35-2.50 mu m, the photosphere appears extended and the radius is larger than in the H band. In this spectral region, the geometrical toy model locates a third bright spot outside the photosphere that can be a feature of the molecular layers. The wavelength dependence of the visibility can be qualitatively explained by 1D dynamical models of Mira atmospheres. The best-fitting photospheric models show a good match with the observed visibilities and give a photospheric diameter of Theta = 8.82 +/- 0.50 mas. The H2O molecule seems to be the dominant absorber in the molecular layers. Conclusions. We show that the atmosphere of VX Sgr seems to resemble Mira/AGB star model atmospheres more closely than do RSG model atmospheres. In particular, we see molecular ( water) layers that are typical of Mira stars.

  • 45. Chiavassa, A.
    et al.
    Pasquato, E.
    Jorissen, A.
    Sacuto, S.
    Babusiaux, C.
    Freytag, Bernd
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ludwig, H. -G
    Cruzalebes, P.
    Rabbia, Y.
    Spang, A.
    Chesneau, O.
    Radiative hydrodynamic simulations of red supergiant stars III. Spectro-photocentric variability, photometric variability, and consequences on Gaia measurements2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 528, A120- p.Article in journal (Refereed)
    Abstract [en]

    Context. It has been shown that convection in red supergiant stars (RSG) gives rise to large granules that cause surface inhomogeneities and shock waves in the photosphere. The resulting motion of the photocentre (on time scales ranging from months to years) could possibly have adverse effects on the parallax determination with Gaia. Aims. We explore the impact of the granulation on the photocentric and photometric variability. We quantify these effects in order to better characterise the error that could possibly alter the parallax. Methods. We use 3D radiative-hydrodynamics (RHD) simulations of convection with CO5BOLD and the post-processing radiative transfer code Optim3D to compute intensity maps and spectra in the Gaia G band [325-1030 nm]. Results. We provide astrometric and photometric predictions from 3D simulations of RSGs that are used to evaluate the possible degradation of the astrometric parameters of evolved stars derived by Gaia. We show in particular from RHD simulations that a supergiant like Betelgeuse exhibits a photocentric noise characterised by a standard deviation of the order of 0.1 AU. The number of bright giant and supergiant stars whose Gaia parallaxes will be altered by the photocentric noise ranges from a few tens to several thousands, depending on the poorly known relation between the size of the convective cells and the atmospheric pressure scale height of supergiants, and to a lower extent, on the adopted prescription for galactic extinction. In the worst situation, the degradation of the astrometric fit caused by this photocentric noise will be noticeable up to about 5 kpc for the brightest supergiants. Moreover, parallaxes of Betelgeuse-like supergiants are affected by an error of the order of a few percents. We also show that the photocentric noise, as predicted by the 3D simulation, does account for a substantial part of the supplementary "cosmic noise" that affects Hipparcos measurements of Betelgeuse and Antares.

  • 46. Chiavassa, A
    et al.
    Plez, B
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Josselin, E
    Freytag, B
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Radiative hydrodynamics simulations of red supergiant stars I. interpretation of interferometric observations2009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 506, no 3, 1351-1365 p.Article in journal (Refereed)
    Abstract [en]

    Context. It has been proposed that convection in red supergiant (RSG) stars produces large-scale granules causing observable surface inhomogeneities. This convection is also extremely vigorous and is suspected to be one of the main causes of mass-loss in RSGs. It should thus be understood in detail. Evidence has accumulated of asymmetries in the photospheres of RSGs, but detailed studies of granulation are still lacking. Interferometric observations provide an innovative way of addressing this question, but they are still often interpreted using smooth symmetrical limb-darkened intensity distributions, or simple, spotted, ad hoc models. Aims. We explore the impact of the granulation on visibility curves and closure phases using the radiative transfer code OPTIM3D. We simultaneously assess how 3D simulations of convection in RSG with (COBOLD)-B-5 can be tested by comparing with these observations. Methods. We use 3D radiative hydrodynamical (RHD) simulations of convection to compute intensity maps at various wavelengths and time, from which we derive interferometric visibility amplitudes and phases. We study their behaviour with time, position angle, and wavelength, and compare them to observations of the RSG alpha Ori. Results. We provide average limb-darkening coefficients for RSGs. We describe the prospects for the detection and characterization of granulation (i.e., contrast, size) on RSGs. We demonstrate that our RHD simulations provide an excellent fit to existing interferometric observations of alpha Ori, in contrast to limb darkened disks. This confirms the existence of large convective cells on the surface of Betelgeuse.

  • 47.
    Christlieb, N.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Schorck, T.
    Frebel, A.
    Beers, T. C.
    Wisotzki, L.
    Reimers, D.
    The stellar content of the Hamburg/ESO survey - IV. Selection of candidate metal-poor stars2008In: Astronomy and Astrophysics, ISSN 0004-6361, Vol. 484, no 3, 721-732 p.Article in journal (Refereed)
    Abstract [en]

    We present the quantitative methods used for selecting candidate metal-poor stars in the Hamburg/ESO objective-prism survey (HES). The selection is based on the strength of the Ca II K line, B - V colors (both measured directly from the digital HES spectra), as well as J - K colors from the 2 Micron All Sky Survey. The KP index for Ca II K can be measured from the HES spectra with an accuracy of 1.0 angstrom, and a calibration of the HES B - V colors, using CCD photometry, yields a 1-sigma uncertainty of 0.07 mag for stars in the color range 0.3 < B - V < 1.4. These accuracies make it possible to reliably reject stars with [Fe/H] > -2.0 without sacrificing completeness at the lowest metallicities. A test of the selection using 1121 stars of the HK survey of Beers, Preston, and Shectman present on HES plates suggests that the completeness at [Fe/H] < -3.5 is close to 100% and that, at the same time, the contamination of the candidate sample with false positives is low: 50% of all stars with [Fe/H] > -2.5 and 97% of all stars with [Fe/H] > -2.0 are rejected. The selection was applied to 379 HES fields, covering a nominal area of 8853 deg(2) of the southern high Galactic latitude sky. The candidate sample consists of 20 271 stars in the magnitude range 10 less than or similar to B less than or similar to 18. A comparison of the magnitude distribution with that of the HK survey shows that the magnitude limit of the HES sample is about 2mag fainter. Taking the overlap of the sky areas covered by both surveys into account, it follows that the survey volume for metal-poor stars has been increased by the HES by about a factor of 10 with respect to the HK survey. We have already identified several very rare objects with the HES, including, e. g., the three most heavy-element deficient stars currently known.

  • 48.
    Cole, E. M.
    et al.
    Univ Helsinki, Dept Phys, FIN-00014 Helsinki, Finland..
    Hackman, T.
    Univ Helsinki, Dept Phys, FIN-00014 Helsinki, Finland.;Univ Turku, Finnish Ctr Astron ESO, Piikkio 21500, Finland..
    Kapyka, M. J.
    Aalto Univ, Dept Comp Sci, ReSoLVE Ctr Excellence, Espoo 00076, Finland..
    Ilyin, I.
    Leibniz Inst Astrophys Potsdam, D-14882 Potsdam, Germany..
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Doppler imaging of LQ Hydrae for 1998-20022015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 581, A69Article in journal (Refereed)
    Abstract [en]

    Aims. We study the spot distribution on the surface of LQ Hya during the observing seasons October 1998-November 2002. We look for persistent active longitudes, trends in the level of spot activity and compare to photometric data. Methods. We apply the Doppler imaging technique on photospheric spectral lines using an inversion code to retrieve images of the surface temperature. Results. We present new temperature maps using multiple spectral lines for a total of 7 seasons. Conclusions. We find no evidence for active longitudes persisting over multiple observing seasons. The spot activity appears to be concentrated to two latitude regions. Using the currently accepted rotation period, we find spot structures to show a trend in the phase-time plot, indicative of a need for a longer period. We conclude that the long-term activity of LQ Hya is more chaotic than that of some magnetically active binary stars analyzed with similar methods, but still with clear indications of an activity cycle from the photometry.

  • 49.
    Collet, Remo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Asplund, Martin
    Trampedach, Regner
    Three-dimensional hydrodynamical simulations of surface convection in red giant stars: Impact on spectral line formation and abundance analysis2007In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 469, no 2, 687-706 p.Article in journal (Refereed)
    Abstract [en]

    Aims. We investigate the impact of realistic three-dimensional (3D) hydrodynamical model atmospheres of red giant stars at different metallicities on the formation of spectral lines of a number of ions and molecules.

    Methods. We carry out realistic, ab initio, 3D, hydrodynamical simulations of surface convection at the surface of red giant stars with varying effective temperatures and metallicities. We use the convection simulations as time-dependent hydrodynamical model stellar atmospheres to calculate spectral lines of a number of ions (Li I, O I, Na I, Mg I, Ca I, Fe I, and Fe II) and molecules ( CH, NH, and OH) under the assumption of local thermodynamic equilibrium (LTE). We carry out a differential comparison of the line strengths computed in 3D with the results of analogous line formation calculations for classical, 1D, hydrostatic, plane-parallel marcs model atmospheres in order to estimate the impact of 3D models on the derivation of elemental abundances.

    Results. The temperature and density inhomogeneities and correlated velocity fields in 3D models, as well as the differences between the mean 3D stratifications and corresponding 1D model atmospheres significantly affect the predicted strengths of spectral lines. Under the assumption of LTE, the low atmospheric temperatures encountered in 3D model atmospheres of very metal-poor giant stars cause spectral lines from neutral species and molecules to appear stronger than within the framework of 1D models. As a consequence, elemental abundances derived from these lines using 3D models are significantly lower than according to 1D analyses. In particular, the differences between 3D and 1D abundances of C, N, and O derived from CH, NH, and OH weak low-excitation lines are found to be in the range - 0.5 dex to - 1.0 dex for the the red giant stars at [Fe/H] = - 3 considered here. At this metallicity, large negative corrections ( about - 0.8 dex) are also found, in LTE, for weak low-excitation Fe I lines. We caution, however, that the neglected departures from LTE might be significant for these and other elements and comparable to the effects due to stellar granulation.

  • 50. Creevey, O. L.
    et al.
    Thevenin, F.
    Berio, P.
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    von Braun, K.
    Mourard, D.
    Bigot, L.
    Boyajian, T. S.
    Kervella, P.
    Morel, P.
    Pichon, B.
    Chiavassa, A.
    Nardetto, N.
    Perraut, K.
    Meilland, A.
    Mc Alister, H. A.
    ten Brummelaar, T. A.
    Farrington, C.
    Sturmann, J.
    Sturmann, L.
    Turner, N.
    Benchmark stars for Gaia Fundamental properties of the Population II star HD 140283 from interferometric, spectroscopic, and photometric data2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 575, A26Article in journal (Refereed)
    Abstract [en]

    Metal-poor halo stars are important astrophysical laboratories that allow us to unravel details about many aspects of astrophysics, including the chemical conditions at the formation of our Galaxy, understanding the processes of diffusion in stellar interiors, and determining precise effective temperatures and calibration of colour-effective temperature relations. To address any of these issues the fundamental properties of the stars must first be determined. HD140283 is the closest and brightest metal-poor Population II halo star (distance = 58 pc and V = 7.21), an ideal target that allows us to approach these questions, and one of a list of 34 benchmark stars defined for Gaia astrophysical parameter calibration. In the framework of characterizing these benchmark stars, we determined the fundamental properties of HD140283 (radius, mass, age, and effective temperature) by obtaining new interferometric and spectroscopic measurements and combining them with photometry from the literature. The interferometric measurements were obtained using the visible interferometer VEGA on the CHARA array and we determined a 1D limb-darkened angular diameter of theta(1D) = 0.353 +/- 0.013 milliarcsec. Using photometry from the literature we derived the bolometric flux in two ways: a zero reddening solution (A(V) = 0.0 mag) of F-bol of 3.890 +/- 0.066 x 10(-8) erg s(-1) cm(-2),and a maximum of A(V) = 0.1 mag solution of 4.220 +/- 0.067 x 10(-8) erg s(-1) cm(-2). The interferometric T-eff is thus between 5534 +/- 103 K and 5647 +/- 105 K and its radius is R = 2.21 +/- 0.08 R-circle dot. Spectroscopic measurements of HD140283 were obtained using HARPS, NARVAL, and UVES and a 1D LTE analysis of Ha line wings yielded T-effspec = 5626 +/- 75 K. Using fine-tuned stellar models including diffusion of elements we then determined the mass M and age t of HD140283. Once the metallicity has been fixed, the age of the star depends on M, initial helium abundance Y-i, and mixing-length parameter alpha, only two of which are independent. We derive simple equations to estimate one from the other two. We need to adjust a to much lower values than the solar one (similar to 2) in order to fit the observations, and if A(V) = 0.0 mag then 0.5 <= alpha <= 1. We give an equation to estimate t from M, Y-i (alpha), and A(V). Establishing a reference alpha = 1.00 and adopting Y-i = 0.245 we derive a mass and age of HD140283: M = 0.780 +/- 0.010 M-circle dot and t = 13.7 +/- 0.7 Gyr (A(V) = 0.0 mag), or M = 0.805 +/- 0.010 M-circle dot and t = 12.2 +/- 0.6 Gyr (A(V) = 0.1 mag). Our stellar models yield an initial (interior) metal-hydrogen mass fraction of [Z/X](i) = -1.70 and log g = 3.65 +/- 0.03. Theoretical advances allowing us to impose the mixing-length parameter would greatly improve the redundancy between M, Y-i, and age, while from an observational point of view, accurate determinations of extinction along with asteroseismic observations would provide critical information allowing us to overcome the current limitations in our results.

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