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  • 1.
    Albert, Damien
    et al.
    Univ Grenoble Alpes, CNRS, OSUG, Unite Mixte Rech 832, F-38000 Grenoble, France..
    Antony, Bobby K.
    Indian Sch Mines, Indian Inst Technol, Dhanbad 826004, Bihar, India..
    Ba, Yaye Awa
    Univ Paris 06, Sorbonne Univ, UPMC, CNRS,LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Babikov, Yuri L.
    Russian Acad Sci, Siberian Branch, VE Zuev Inst Atmospher Opt, Zuev Sq 1, Tomsk 634055, Russia.;Tomsk State Univ, Phys Dept, Lab Quantum Mech & Radiat Transfer QUAMER, Tomsk 634050, Russia..
    Bollard, Philippe
    Univ Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France..
    Boudon, Vincent
    Univ Bourgogne Franche Comte, Lab Interdisciplinaire Carnot Bourgogne, CNRS, UMR 6303, 9 Ave Alain Savary,BP 47 870, F-21078 Dijon, France..
    Delahaye, Franck
    Univ Paris 06, Sorbonne Univ, UPMC, CNRS,LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Del Zanna, Giulio
    DAMTP, Ctr Math Sci, Wilberforce Rd, Cambridge CB3 0WA, England..
    Dimitrijevic, Milan S.
    Univ Paris 06, Sorbonne Univ, UPMC, CNRS,LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France.;Astron Observ, Volgina 7, Belgrade 11060, Serbia..
    Drouin, Brian J.
    CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Dubernet, Marie-Lise
    Univ Paris 06, Sorbonne Univ, UPMC, CNRS,LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Duensing, Felix
    Univ Innsbruck, Inst Ion Phys & Appl Phys, Technikerstr 25-3, A-6020 Innsbruck, Austria..
    Emoto, Masahiko
    Natl Inst Nat Sci, Natl Inst Fus Sci, Toki, Gifu 5095292, Japan..
    Endres, Christian P.
    Max Planck Inst Extraterr Phys, Giessenbachstr, D-85748 Garching, Germany..
    Fazliev, Alexandr Z.
    Russian Acad Sci, Siberian Branch, VE Zuev Inst Atmospher Opt, Zuev Sq 1, Tomsk 634055, Russia..
    Glorian, Jean-Michel
    Univ Toulouse UPS, Inst Rech Astrophys & Planetol, CNRS, CNES, 9 Av Colonel Roche, F-31028 Toulouse 4, France..
    Gordon, Iouli E.
    Ctr Astrophys Harvard & Smithsonian, Atom & Mol Phys Div, MS50,60 Garden St, Cambridge, MA 02138 USA..
    Gratier, Pierre
    Univ Bordeaux, CNRS, Lab Astrophys Bordeaux, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Hill, Christian
    Vienna Int Ctr, Div Phys & Chem Sci, Nucl Data Sect, Int Atom Energy Agcy IAEA, A-1400 Vienna, Austria..
    Jevremovic, Darko
    Astron Observ, Volgina 7, Belgrade 11060, Serbia..
    Joblin, Christine
    Univ Toulouse UPS, Inst Rech Astrophys & Planetol, CNRS, CNES, 9 Av Colonel Roche, F-31028 Toulouse 4, France..
    Kwon, Duck-Hee
    Korea Atom Energy Res Inst, Nucl Data Ctr, Daejeon 34057, South Korea..
    Kochanov, Roman V.
    Russian Acad Sci, Siberian Branch, VE Zuev Inst Atmospher Opt, Zuev Sq 1, Tomsk 634055, Russia.;Tomsk State Univ, Phys Dept, Lab Quantum Mech & Radiat Transfer QUAMER, Tomsk 634050, Russia..
    Krishnakumar, Erumathadathil
    Raman Res Inst, CV Raman Ave, Bangalore 560080, Karnataka, India..
    Leto, Giuseppe
    INAF Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy..
    Loboda, Petr A.
    All Russian Inst Tech Phys RFNC VNIITF, Russian Fed Nucl Ctr, Snezhinsk 456770, Russia.;Natl Res Nucl Univ, Moscow Engn Phys Inst MEPhI, Moscow 115409, Russia..
    Lukashevskaya, Anastasiya A.
    Russian Acad Sci, Siberian Branch, VE Zuev Inst Atmospher Opt, Zuev Sq 1, Tomsk 634055, Russia..
    Lyulin, Oleg M.
    Russian Acad Sci, Siberian Branch, VE Zuev Inst Atmospher Opt, Zuev Sq 1, Tomsk 634055, Russia..
    Marinkovic, Bratislav P.
    Univ Belgrade, Inst Phys Belgrade, POB 57, Belgrade 11001, Serbia..
    Markwick, Andrew
    Univ Manchester, Sch Phys & Astron, Jodrell Bank Ctr Astrophys, Oxford Rd, Manchester M13 9PL, Lancs, England..
    Marquart, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Mason, Nigel J.
    Univ Kent, Sch Phys Sci, Ingram Bldg, Canterbury CT2 7NH, Kent, England..
    Mendoza, Claudio
    Western Michigan Univ, Dept Phys, Kalamazoo, MI 49008 USA..
    Millar, Tom J.
    Queens Univ Belfast, Sch Math & Phys, Univ Rd, Belfast BT7 1NN, Antrim, North Ireland..
    Moreau, Nicolas
    Univ Paris 06, Sorbonne Univ, UPMC, CNRS,LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Morozov, Serguei V.
    All Russian Inst Tech Phys RFNC VNIITF, Russian Fed Nucl Ctr, Snezhinsk 456770, Russia..
    Moeller, Thomas
    Univ Cologne, Phys Inst 1, Zulpicher Str 77, D-50937 Cologne, Germany..
    Mueller, Holger S. P.
    Univ Cologne, Phys Inst 1, Zulpicher Str 77, D-50937 Cologne, Germany..
    Mulas, Giacomo
    Univ Toulouse UPS, Inst Rech Astrophys & Planetol, CNRS, CNES, 9 Av Colonel Roche, F-31028 Toulouse 4, France.;Osservatorio Astron Cagliari, Ist Nazl AstroFis, Via Sci 5, I-09047 Selargius, CA, Italy..
    Murakami, Izumi
    Natl Inst Nat Sci, Natl Inst Fus Sci, Toki, Gifu 5095292, Japan.;Grad Univ Adv Studies, Dept Fus Sci, SOKENDAI, Toki, Gifu 5095292, Japan..
    Pakhomov, Yury
    Russian Acad Sci, Inst Astron, Pyatnitskaya 48, Moscow 119017, Russia..
    Palmeri, Patrick
    Univ Mons, Phys Atom & Astrophys, B-7000 Mons, Belgium..
    Penguen, Julien
    Univ La Rochelle, Observ Aquitain Sci Univers, Univ Bordeaux, POREA,CNRS,IRSTEA, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Perevalov, Valery I.
    Russian Acad Sci, Siberian Branch, VE Zuev Inst Atmospher Opt, Zuev Sq 1, Tomsk 634055, Russia..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Postler, Johannes
    Univ Innsbruck, Inst Ion Phys & Appl Phys, Technikerstr 25-3, A-6020 Innsbruck, Austria..
    Privezentsev, Alexei I.
    Russian Acad Sci, Siberian Branch, VE Zuev Inst Atmospher Opt, Zuev Sq 1, Tomsk 634055, Russia..
    Quinet, Pascal
    Univ Mons, Phys Atom & Astrophys, B-7000 Mons, Belgium.;Univ Liege, IPNAS, B-4000 Liege, Belgium..
    Ralchenko, Yuri
    Natl Inst Stand & Technol, Atom Spect Grp, Gaithersburg, MD 20899 USA..
    Rhee, Yong-Joo
    Inst Basic Sci, Ctr Relativist Laser Sci, Gwang Ju 61005, South Korea..
    Richard, Cyril
    Univ Bourgogne Franche Comte, Lab Interdisciplinaire Carnot Bourgogne, CNRS, UMR 6303, 9 Ave Alain Savary,BP 47 870, F-21078 Dijon, France..
    Rixon, Guy
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Rothman, Laurence S.
    Ctr Astrophys Harvard & Smithsonian, Atom & Mol Phys Div, MS50,60 Garden St, Cambridge, MA 02138 USA..
    Roueff, Evelyne
    Univ Paris 06, Sorbonne Univ, UPMC, CNRS,LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Ryabchikova, Tatiana
    Russian Acad Sci, Inst Astron, Pyatnitskaya 48, Moscow 119017, Russia..
    Sahal-Brechot, Sylvie
    Univ Paris 06, Sorbonne Univ, UPMC, CNRS,LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Scheier, Paul
    Univ Innsbruck, Inst Ion Phys & Appl Phys, Technikerstr 25-3, A-6020 Innsbruck, Austria..
    Schilke, Peter
    Univ Cologne, Phys Inst 1, Zulpicher Str 77, D-50937 Cologne, Germany..
    Schlemmer, Stephan
    Univ Cologne, Phys Inst 1, Zulpicher Str 77, D-50937 Cologne, Germany..
    Smith, Ken W.
    Queens Univ Belfast, Sch Math & Phys, Univ Rd, Belfast BT7 1NN, Antrim, North Ireland..
    Schmitt, Bernard
    Univ Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France..
    Skobelev, Igor Yu.
    Natl Res Nucl Univ, Moscow Engn Phys Inst MEPhI, Moscow 115409, Russia.;Russian Acad Sci, Joint Inst High Temp, Moscow 141570, Russia..
    Sreckovic, Vladimir A.
    Univ Belgrade, Inst Phys Belgrade, POB 57, Belgrade 11001, Serbia..
    Stempels, H. C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Tashkun, Serguey A.
    Russian Acad Sci, Siberian Branch, VE Zuev Inst Atmospher Opt, Zuev Sq 1, Tomsk 634055, Russia..
    Tennyson, Jonathan
    UCL, Dept Phys & Astron, London WC1E 6BT, England..
    Tyuterev, Vladimir G.
    Tomsk State Univ, Phys Dept, Lab Quantum Mech & Radiat Transfer QUAMER, Tomsk 634050, Russia.;UFR Sci, CNRS, Grp Spectrometr Mol & Atmospher GSMA, UMR 7331, BP 1039-51687, Reims 2, France..
    Vastel, Charlotte
    Univ Toulouse UPS, Inst Rech Astrophys & Planetol, CNRS, CNES, 9 Av Colonel Roche, F-31028 Toulouse 4, France..
    Vujcic, Veljko
    Astron Observ, Volgina 7, Belgrade 11060, Serbia.;Univ Belgrade, Fac Org Sci, Jove Ilica 33, Belgrade 11000, Serbia..
    Wakelam, Valentine
    Univ Bordeaux, CNRS, Lab Astrophys Bordeaux, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Walton, Nicholas A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Zeippen, Claude
    Univ Paris 06, Sorbonne Univ, UPMC, CNRS,LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Zwolf, Carlo Maria
    Univ Paris 06, Sorbonne Univ, UPMC, CNRS,LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    A Decade with VAMDC: Results and Ambitions2020In: Atoms, E-ISSN 2218-2004, Vol. 8, no 4, article id 76Article in journal (Refereed)
    Abstract [en]

    This paper presents an overview of the current status of the Virtual Atomic and Molecular Data Centre (VAMDC) e-infrastructure, including the current status of the VAMDC-connected (or to be connected) databases, updates on the latest technological development within the infrastructure and a presentation of some application tools that make use of the VAMDC e-infrastructure. We analyse the past 10 years of VAMDC development and operation, and assess their impact both on the field of atomic and molecular (A&M) physics itself and on heterogeneous data management in international cooperation. The highly sophisticated VAMDC infrastructure and the related databases developed over this long term make them a perfect resource of sustainable data for future applications in many fields of research. However, we also discuss the current limitations that prevent VAMDC from becoming the main publishing platform and the main source of A&M data for user communities, and present possible solutions under investigation by the consortium. Several user application examples are presented, illustrating the benefits of VAMDC in current research applications, which often need the A&M data from more than one database. Finally, we present our vision for the future of VAMDC.

    Download full text (pdf)
    FULLTEXT01
  • 2.
    Aronson, Erik
    et al.
    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.
    Model-free inverse method for transit imaging of stellar surfaces: Using transit surveys to map stellar spot coverage2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 630, article id A122Article in journal (Refereed)
    Abstract [en]

    Context: We present a model-free method for mapping surface brightness variations.

    Aims: We aim to develop a method that is not dependent on either stellar atmosphere models or limb-darkening equation. This method is optimized for exoplanet transit surveys such that a large database of stellar spot coverage can be created.

    Methods: The method uses light curves from several transit events of the same system. These light curves are phase-folded and median-combined to for a high-quality light curve without temporal local brightness variations. Stellar specific intensities are extracted from this light curve using a model-free method. We search individual light curves for departures from the median-combined light curve. Such departures are interpreted as brightness variations on the stellar surface. A map of brightness variations on the stellar surface is produced by finding the brightness distribution that can produce a synthetic light curve that fits observations well. No assumptions about the size, shape, or contrast of brightness variations are made.

    Results: We successfully reproduce maps of stellar disks from both synthetic data and archive observations from FORS2, the visual and near UV FOcal Reducer and low dispersion Spectrograph for the Very Large Telescope (VLT).

  • 3.
    Aronson, Erik
    et al.
    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.
    Model-independent Exoplanet Transit Spectroscopy2018In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 155, no 5, article id 208Article in journal (Refereed)
    Abstract [en]

    We propose a new data analysis method for obtaining transmission spectra of exoplanet atmospheres and brightness variation across the stellar disk from transit observations. The new method is capable of recovering exoplanet atmosphere absorption spectra and stellar specific intensities without relying on theoretical models of stars and planets. We simultaneously fit both stellar specific intensity and planetary radius directly to transit light curves. This allows stellar models to be removed from the data analysis. Furthermore, we use a data quality weighted filtering technique to achieve an optimal trade-off between spectral resolution and reconstruction fidelity homogenizing the signal-to-noise ratio across the wavelength range. Such an approach is more efficient than conventional data binning onto a low-resolution wavelength grid. We demonstrate that our analysis is capable of reproducing results achieved by using an explicit quadratic limb-darkening equation and that the filtering technique helps eliminate spurious spectral features in regions with strong telluric absorption. The method is applied to the VLT FORS2 observations of the exoplanets GJ 1214 b and WASP-49 b, and our results are in agreement with previous studies. Comparisons between obtained stellar specific intensity and numerical models indicates that the method is capable of accurately reconstructing the specific intensity. The proposed method enables more robust characterization of exoplanetary atmospheres by separating derivation of planetary transmission and stellar specific intensity spectra (that is model-independent) from chemical and physical interpretation.

  • 4.
    Barklem, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    O'Mara, B. J.
    Stempels, H. C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Hydrogen Line Formation in Cool Stars2001In: 11th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun / [ed] Garcia Lopez, Ramon J.; Rebolo, Rafael; Zapaterio Osorio, Mario Rosa, San Francisco: Astronomical Society of the Pacific , 2001, p. 766-Conference paper (Other academic)
  • 5.
    Barklem, Paul
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Hydrogen Balmer Lines as Probes of Stellar Atmospheres2003In: IAUS 210, Modelling of stellar atmospheres, 2003, p. E28-Conference paper (Other scientific)
  • 6.
    Barklem, Paul
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    O'Mara, BJ
    A list of data for the broadening of metallic lines by neutral hydrogen collisions2000In: ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES, ISSN 0365-0138, Vol. 142, no 3, p. 467-473Article in journal (Refereed)
  • 7.
    Barklem, Paul
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    O'Mara, BJ
    Self broadening of hydrogen lines: initial results2000In: ASTRONOMY AND ASTROPHYSICS, ISSN 0004-6361, Vol. 355, no 1, p. L5-L8Article in journal (Refereed)
  • 8.
    Barklem, Paul
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    O'Mara, BJ
    Self-broadening in Balmer line wing formation in stellar atmospheres2000In: ASTRONOMY AND ASTROPHYSICS, ISSN 0004-6361, Vol. 363, no 3, p. 1091-1105Article in journal (Refereed)
  • 9.
    Barklem, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Stempels, H.C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Allende Prieto, C.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    O'Mara, B.J.
    Detailed analysis of Balmer lines in cool dwarf stars2002In: Astronomy & Astrophysics, ISSN 0004-6361, Vol. 385, p. 951-Article in journal (Refereed)
  • 10.
    Barklem, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Stempels, H.C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    O'Mara, J.B.
    Balmer lines and effective temperatures in cool stars2003In: 12th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, 2003, p. 1103-Conference paper (Other academic)
  • 11.
    Boyarchuk, A. A.
    et al.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Shustov, B. M.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Savanov, I. S.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Sachkov, M. E.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Bisikalo, D. V.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Mashonkina, L. I.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Wiebe, D. Z.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Shematovich, V. I.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Shchekinov, Yu. A.
    Southern Fed Univ, Rostov Na Donu 344006, Russia..
    Ryabchikova, T. A.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Chugai, N. N.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Ivanov, P. B.
    Russian Acad Sci, Lebedev Phys Inst, Ctr Astro Space, Moscow, Russia..
    Voshchinnikov, N. V.
    St Petersburg State Univ, St Petersburg 199034, Russia..
    Gomez de Castro, A. I.
    Univ Complutense Madrid, Plaza Ciencias 3, E-28040 Madrid, Spain..
    Lamzin, S. A.
    Moscow MV Lomonosov State Univ, Sternberg Astron Inst, Moscow 119992, Russia..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ayres, T.
    Univ Colorado, Boulder, CO 80309 USA..
    Strassmeier, K. G.
    Leibniz Inst Astrophys Potsdam, Sternwarte 16, D-14482 Potsdam, Germany..
    Jeffrey, S.
    Armagh Observ, Coll Hill, Armagh BT61 9DG, North Ireland..
    Zwintz, S. K.
    Univ Innsbruck, Tech Str 25-8, A-6020 Innsbruck, Austria..
    Shulyak, D.
    Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Gerard, J. -C
    Hubert, B.
    Univ Liege, LPAP, Liege, Belgium..
    Fossati, L.
    Austrian Acad Sci, Space Res Inst, Schmiedlstr 6, A-8042 Graz, Austria..
    Lammer, H.
    Austrian Acad Sci, Space Res Inst, Schmiedlstr 6, A-8042 Graz, Austria..
    Werner, K.
    Univ Tubingen, Tubingen, Germany..
    Zhilkin, A. G.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Kaigorodov, P. V.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Sichevskii, S. G.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Ustamuich, S.
    Univ Complutense Madrid, Plaza Ciencias 3, E-28040 Madrid, Spain..
    Kanev, E. N.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Kil'pio, E. Yu.
    Russian Acad Sci, Inst Astron, Ul Pyatnitskaya 48, Moscow 119017, Russia..
    Scientific problems addressed by the Spektr-UV space project (world space Observatory-Ultraviolet)2016In: Astronomy reports (Print), ISSN 1063-7729, E-ISSN 1562-6881, Vol. 60, no 1, p. 1-42Article in journal (Refereed)
    Abstract [en]

    The article presents a review of scientific problems and methods of ultraviolet astronomy, focusing on perspective scientific problems (directions) whose solution requires UV space observatories. These include reionization and the history of star formation in the Universe, searches for dark baryonic matter, physical and chemical processes in the interstellar medium and protoplanetary disks, the physics of accretion and outflows in astrophysical objects, from Active Galactic Nuclei to close binary stars, stellar activity (for both low-mass and high-mass stars), and processes occurring in the atmospheres of both planets in the solar system and exoplanets. Technological progress in UV astronomy achieved in recent years is also considered. The well advanced, international, Russian-led Spektr-UV (World Space Observatory-Ultraviolet) project is described in more detail. This project is directed at creating a major space observatory operational in the ultraviolet (115-310 nm). This observatory will provide an effective, and possibly the only, powerful means of observing in this spectral range over the next ten years, and will be an powerful tool for resolving many topical scientific problems.

  • 12. Brewer, John M.
    et al.
    Fischer, Debra A.
    Basu, Sarbani
    Valenti, Jeff A.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Accurate Gravities of F, G, and K Stars from High Resolution Spectra Without External Constraints2015In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 805, no 2, article id 126Article in journal (Refereed)
    Abstract [en]

    We demonstrate a new procedure to derive accurate and precise surface gravities from high resolution spectra without the use of external constraints. Our analysis utilizes Spectroscopy Made Easy with robust spectral line constraints and uses an iterative process to mitigate degeneracies in the fitting process. We adopt an updated radiative transfer code, a new treatment for neutral perturber broadening, a line list with multiple gravity constraints and separate fitting for global stellar properties and abundance determinations. To investigate the sources of temperature dependent trends in determining log g noted in previous studies, we obtained Keck HIRES spectra of 42 Kepler asteroseismic stars. In comparison to asteroseismically determined log g our spectroscopic analysis has a constant offset of 0.01 dex with a rms scatter of 0.05 dex. We also analyzed 30 spectra which had published surface gravities determined using the a/R-* technique from planetary transits and found a constant offset of 0.06 dex and rms scatter of 0.07 dex. The two samples covered effective temperatures between 5000 and 6700 K with log g between 3.7 and 4.6.

  • 13. Briquet, M.
    et al.
    Aerts, C.
    Lüftinger, T.
    De Cat, P.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Scuflaire, R.
    He and Si surface inhomogeneities of four Bp variable stars2004In: Astronomy & Astrophysics, ISSN 0004-6361, Vol. 413, p. 273-Article in journal (Other scientific)
  • 14.
    Bristow, Paul
    et al.
    ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Baruffolo, Andrea
    INAF Osservatorio Astron Padova, Padua, Italy..
    Smoker, Jonathan
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Rodler, Florian
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Dorn, Reinhold J.
    ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Cumani, Claudio
    ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Ives, Derek J.
    ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Jung, Yves
    ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Marquart, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Moins, Christophe
    ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Neeser, Mark J.
    ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Oliva, Ernesto
    INAF Arcetri Osservatorio, Largo E Fermi 5, I-50125 Florence, Italy..
    Paufique, Jerome
    ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Schmutzer, Ricardo
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Seemann, Ulf
    ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Slumstrup, Ditte
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Valenzuela, Jose Javier
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    CRIRES+: Characterisation and preparation during the pandemic2022In: Ground-based and Airborne Instrumentation for Astronomy IX / [ed] Evans, CJ Bryant, JJ Motohara, K, SPIE - International Society for Optical Engineering, 2022, article id 121845XConference paper (Refereed)
    Abstract [en]

    In early 2020 the upgraded(1) CRIRES2 instrument, was installed at the VLT, however the onset of the global pandemic prevented the completion of some aspects of the installation while characterisation and commissioning had to be conducted with a remote connection from Europe. This resulted in a somewhat experimental, ad-hoc, approach to characterisation that required tight co-ordination between Paranal scientists and the instrument team in Europe. Moreover, with the observatory operating at minimal staffing, we had to find workarounds for some unfinished parts of the installation and adapt our characterisation, calibration and operations strategies accordingly. In particular, we discuss the adaptation made to the metrology strategy that illustrates well the pragmatic and ultimately successful approach adopted for getting CRIRES+ ready for operations.

  • 15. Brown, A.
    et al.
    Korhonen, H.
    Berdyugina, S.
    Tofany, B.
    Ayres, T. R.
    Kowalski, A.
    Hawley, S.
    Harper, G.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Starspot variability and evolution from modeling Kepler photometry of active late-type stars2011In: IAU Symposium 273 (The Physics of Sun and Star Spots), 2011, Vol. 273, p. 78-82Conference paper (Refereed)
    Abstract [en]

    The Kepler satellite provides a unique opportunity to study the detailed optical photometric variability of late-type stars with unprecedentedly long (several year) continuous monitoring and sensitivity to very small-scale variations. We are studying a sample of over two hundred cool (mid-A - late-K spectral type) stars using Kepler long-cadence (30 minute sampling) observations. These stars show a remarkable range of photometric variability, but in this paper we concentrate on rotational modulation due to starspots and flaring. Modulation at the 0.1% level is readily discernable. We highlight the rapid timescales of starspot evolution seen on solar-like stars with rotational periods between 2 and 7 days.

  • 16. Brown, A.
    et al.
    Korhonen, H.
    Berdyugina, S.
    Walkowicz, L.
    Kowalski, A.
    Hawley, S.
    Neff, J.
    Ramsey, L.
    Redman, S.
    Saar, S.
    Furesz, G.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Harper, G.
    Ayres, T.
    Tofany, B.
    Kepler Observations of Starspot Evolution, Differential Rotation, and Flares on Late-Type Stars2011In: American Astronomical Society Meeting Abstracts #218, 2011Conference paper (Refereed)
    Abstract [en]

    The Kepler satellite is providing spectacular optical photometric light-curves of unprecedented precision and duration that routinely allow detailed studies of stellar magnetic activity on late-type stars that were difficult, if not impossible, to attempt previously. Rotational modulation due to starspots is commonly seen in the Kepler light-curves of late-type stars, allowing detailed study of the surface distribution of their photospheric magnetic activity. Kepler is providing multi-year duration light-curves that allow us to investigate how activity phenomena – such as the growth, migration, and decay of starspots, differential rotation, activity cycles, and flaring – operate on single and binary stars with a wide range of mass and convection zone depth. We present the first results from detailed starspot modeling using newly-developed light-curve inversion codes for a range of GALEX-selected stars with typical rotation periods of a few days, that we have observed as part of our 200 target Kepler Cycle 1/2 Guest Observer programs. The physical properties of the stars have been measured using high resolution optical spectroscopy, which allows the Kepler results to be placed within the existing framework of knowledge regarding stellar magnetic activity. These results demonstrate the powerful diagnostic capability provided by tracking starspot evolution essentially continuously for more than 16 months. The starspots are clearly sampling the stellar rotation rate at different latitudes, enabling us to measure the differential rotation and starspot lifetimes. As would be expected, stars with few day rotation show frequent flaring that is easily seen as ”white-light” flares in Kepler light-curves. We compare the observed flare rates and occurrence with the starspot properties. This work contains results obtained using the NASA Kepler satellite and from the Apache Point Observatory, the MMT (using NOAO community access time), and the Hobby-Eberly Telescope. Funding is provided by NASA Kepler grants NNX10AC51G and NNX11AC79G.

  • 17. Brown, Alexander
    et al.
    Neff, James E.
    Ayres, Thomas R.
    Kowalski, Adam
    Hawley, Suzanne
    Berdyugina, Svetlana
    Harper, Graham M.
    Korhonen, Heidi
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Saar, Steven
    Walkowicz, Lucianne
    Wells, Mark A.
    Serendipitous Discovery of a Dwarf Nova in the Kepler Field Near the G Dwarf Kic 54388452015In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 149, no 2, article id 67Article in journal (Refereed)
    Abstract [en]

    The Kepler satellite provides a unique window into stellar temporal variability by observing a wide variety of stars with multi-year, near-continuous, high precision, optical photometric time series. While most Kepler targets are faint stars with poorly known physical properties, many unexpected discoveries should result from a long photometric survey of such a large area of sky. During our Kepler Guest Observer programs that monitored late-type stars for starspot and flaring variability, we discovered a previously unknown dwarf nova that lies within a few arcseconds of the mid-G dwarf star KIC 5438845. This dwarf nova underwent nine outbursts over a 4 year time span. The two largest outbursts lasted similar to 17-18 days and show strong modulations with a 110.8 minute period and a declining amplitude during the outburst decay phase. These properties are characteristic of an SU UMa-type cataclysmic variable. By analogy with other dwarf nova light curves, we associate the 110.8 minute (1.847 hr) period with the superhump period, close to but slightly longer than the orbital period of the binary. No precursor outbursts are seen before the super-outbursts and the overall super-outburst morphology corresponds to Osaki & Meyer "Case B" outbursts, which are initiated when the outer edge of the disk reaches the tidal truncation radius. "Case B" outbursts are rare within the Kepler light curves of dwarf novae. The dwarf nova is undergoing relatively slow mass transfer, as evidenced by the long intervals between outbursts, but the mass transfer rate appears to be steady, because the smaller "normal" outbursts show a strong correlation between the integrated outburst energy and the elapsed time since the previous outburst. At super-outburst maximum the system was at V similar to 18, but in quiescence it is fainter than V similar to 22, which will make any detailed quiescent follow-up of this system difficult.

  • 18.
    Brucalassi, Anna
    et al.
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Dorn, Reinhold J.
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Follert, Roman
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany.
    Hatzes, Artie
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany.
    Bristow, Paul
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Seemann, Ulf
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.
    Cumani, Claudio
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Eschbaumer, Siegfried
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Haimerl, Andreas
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Haug, Marcus
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Hinterschuster, Renate
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Ives, Derek J.
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Jung, Yves
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Kerber, Florian
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Klein, Barbara
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Lavail, Alexis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Lizon, Jean Louis
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Marquart, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Moins, Christophe
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Molina-Conde, Ignacio
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Oliva, Ernesto
    Osservatorio Arcetri, INAF, Largo E Fermi 5, I-50125 Florence, Italy.
    Pasquini, Luca
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Paufique, Jerome
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Stegmeier, Joerg
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Stempels, Eric H. C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Tordo, Sebastien
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Valenti, Elena
    ESO, Karl Schwarzschild Strae 2, D-85748 Garching, Germany.
    Anwand-Heerwart, Heiko
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.
    Hauptner, Katja
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.
    Jeep, Peter
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.
    Marvin, Christopher
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.
    Reiners, Ansgar
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.
    Rhode, Petra
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.
    Schmidt, Christof
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.
    Umlauf, Tim
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.
    Full System Test and early Preliminary Acceptance Europe results for CRIRES2018In: Ground-Based And Airborne Instrumentation For Astronomy VII / [ed] Evans, CJ, Simard, L, Takami, H, 2018, article id UNSP 1070239Conference paper (Refereed)
    Abstract [en]

    CRIRES+ is the new high-resolution NIR echelle spectrograph intended to be operated at the platform B of VLT Unit telescope UT3. It will cover from Y to M bands (0.95-5.3um) with a spectral resolution of R = 50000 or R = 100000. The main scientific goals are the search of super-Earths in the habitable zone of low-mass stars, the characterisation of transiting planets atmosphere and the study of the origin and evolution of stellar magnetic fields. Based on the heritage of the old adaptive optics (AO) assisted VLT instrument CRIRES, the new spectrograph will present improved optical layout, a new detector system and a new calibration unit providing optimal performances in terms of simultaneous wavelength coverage and radial velocity accuracy (a few m/s). The total observing efficiency will be enhanced by a factor of 10 with respect to CRIRES. An innovative spectro-polarimetry mode will be also offered and a new metrology system will ensure very high system stability and repeatability. Fiinally, the CRIRES+ project will also provide the community with a new data reduction software (DRS) package. CRIRES+ is currently at the initial phase of its Preliminary Acceptance in Europe (PAE) and it will be commissioned early in 2019 at VLT. This work outlines the main results obtained during the initial phase of the full system test at ESO HQ Garching.

  • 19.
    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, Observational 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, article id 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.

  • 20.
    Cole-Kodikara, Elizabeth M.
    et al.
    Leibniz Inst Astrophys Potsdam, Sternwarte 16, D-14482 Potsdam, Germany.
    Kaepylae, Maarit J.
    Max Planck Inst Solar Syst Res, Justus von Liebig Weg 3, Gottingen, Germany;Aalto Univ, ReSoLVE Ctr Excellence, Dept Comp Sci, Helsinki, Finland.
    Lehtinen, Jyri J.
    Max Planck Inst Solar Syst Res, Justus von Liebig Weg 3, Gottingen, Germany;Aalto Univ, ReSoLVE Ctr Excellence, Dept Comp Sci, Helsinki, Finland.
    Hackman, Thomas
    Univ Helsinki, Dept Phys, POB 64, FIN-00014 Helsinki, Finland.
    Ilyin, Ilya, V
    Leibniz Inst Astrophys Potsdam, Sternwarte 16, D-14482 Potsdam, Germany.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Spot evolution on LQ Hya from 2006-2017: temperature maps based on SOFIN and FIES data2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 629, no Sept, article id A120Article in journal (Refereed)
    Abstract [en]

    Context. LQ Hya is one of the most frequently studied young solar analogue stars. Recently, it has been observed to show intriguing behaviour when analysing long-term photometry. For instance, from 2003-2009, a coherent spot structure migrating in the rotational frame was reported by various authors. However, ever since, the star has entered a chaotic state where coherent structures seem to have disappeared and rapid phase jumps of the photometric minima occur irregularly over time. Aims. LQ Hya is one of the stars included in the SOFIN/FIES long-term monitoring campaign extending over 25 yr. Here, we publish new temperature maps for the star during 2006-2017, covering the chaotic state of the star. Methods. We used a Doppler imaging technique to derive surface temperature maps from high-resolution spectra. Results. From the mean temperatures of the Doppler maps, we see a weak but systematic increase in the surface temperature of the star. This is consistent with the simultaneously increasing photometric magnitude. During nearly all observing seasons, we see a high-latitude spot structure which is clearly non-axisymmetric. The phase behaviour of this structure is very chaotic but agrees reasonably well with the photometry. Equatorial spots are also frequently seen, but we interpret many of them to be artefacts due to the poor to moderate phase coverage. Conclusions. Even during the chaotic phase of the star, the spot topology has remained very similar to the higher activity epochs with more coherent and long-lived spot structures. In particular, we see high-latitude and equatorial spot activity, the mid latitude range still being most often void of spots. We interpret the erratic jumps and drifts in phase of the photometric minima to be caused by changes in the high-latitude spot structure rather than the equatorial spots.

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  • 21. Cowley, C.R.
    et al.
    Hubrig, S.
    Ryabchikova, T.A.
    Mathys, G.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Mittermayer, P.
    The core-wing anomaly of cool Ap stars - Abnormal Balmer profiles2001In: Astronomy & Astrophysics, ISSN 0004-6361, Vol. 367, no 3, p. 939-942Article in journal (Refereed)
  • 22.
    de Jong, Roelof S.
    et al.
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Barden, Samuel C.
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Bellido-Tirado, Olga
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Brynnel, Joar G.
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Frey, Steffen
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Giannone, Domenico
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Haynes, Roger
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany.;InnoFSPEC, Potsdam, Germany..
    Johl, Diana
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Phillips, Daniel
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Schnurr, Olivier
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Walcher, Jakob C.
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Winkler, Roland
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Ansorge, Wolfgang R.
    RAMS CON Management Consultants, Assling, Germany..
    Feltzing, Sofia
    Lund Observ, Lund, Sweden..
    McMahon, Richard G.
    Univ Cambridge, Cambridge CB2 1TN, England..
    Baker, Gabriella
    Australian Astron Observ, Sydney, NSW, Australia..
    Caillier, Patrick
    Ctr Rech Astrophys Lyon, Lyon, France..
    Dwelly, Tom
    Max Planck Inst Extraterr Phys, Munich, Germany..
    Gaessler, Wolfgang
    Max Planck Inst Astron, Heidelberg, Germany..
    Iwer, Olaf
    European Southern Observ, Garching, Germany..
    Mandel, Holger G.
    Heidelberg Univ, Zentrum Astron, Heidelberg, Germany..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Pragt, Johan H.
    NOVA ASTRON, Dwingeloo, Netherlands..
    Walton, Nicholas A.
    Univ Cambridge, Cambridge CB2 1TN, England..
    Bensby, Thomas
    Lund Observ, Lund, Sweden..
    Bergemann, Maria
    Max Planck Inst Astron, Heidelberg, Germany..
    Chiappini, Cristina
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Christlieb, Norbert
    Heidelberg Univ, Zentrum Astron, Heidelberg, Germany..
    Cioni, Maria-Rosa L.
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Driver, Simon
    Univ Western Australia, Perth, WA, Australia..
    Finoguenov, Alexis
    Max Planck Inst Extraterr Phys, Munich, Germany..
    Helmi, Amina
    Kapteyn Astron Inst, Groningen, Netherlands..
    Irwin, Michael J.
    Univ Cambridge, Cambridge CB2 1TN, England..
    Kitaur, Francisco-Shu
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Kneib, Jean-Paul
    Ecole Polytech Fed Lausanne, CH-1015 Lausanne, Switzerland..
    Liske, Jochen
    Univ Hamburg, Hamburg, Germany. Univ Potsdam, Potsdam, Germany. Univ Hertfordshire, Hatfield AL10 9AB, Herts, England..
    Merloni, Andrea
    Max Planck Inst Extraterr Phys, Munich, Germany..
    Minchev, Ivan
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    Richard, Johan
    Ctr Rech Astrophys Lyon, Lyon, France..
    Starkenburg, Else
    Leibniz Inst Astrophys Potsdam AIP, An Sternwarte 16, D-14482 Potsdam, Germany..
    4MOST: the 4-metre Multi-Object Spectroscopic Telescope project at preliminary design review2016In: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY VI / [ed] Christopher J Evans, 2016, Vol. 9908, article id UNSP 99081OConference paper (Refereed)
    Abstract [en]

    We present an overview of the 4MOST project at the Preliminary Design Review. 4MOST is a major new wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of ESO. 4MOST has a broad range of science goals ranging from Galactic Archaeology and stellar physics to the high-energy physics, galaxy evolution, and cosmology. Starting in 2021, 4MOST will deploy 2436 fibres in a 4.1 square degree field-of-view using a positioner based on the tilting spine principle. The fibres will feed one high-resolution (R similar to 20,000) and two medium-resolution (R similar to 5000) spectrographs with fixed 3-channel designs and identical 6k x 6k CCD detectors. 4MOST will have a unique operations concept in which 5-year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept, showing that we can expect to observe more than 25 million objects in each 5-year survey period and will eventually be used to plan and conduct the actual survey.

  • 23.
    Dorn, R. J.
    et al.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Bristow, P.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Smoker, J. V.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Rodler, F.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Lavail, Alexis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Accardo, M.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    van den Ancker, M.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Baade, D.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Baruffolo, A.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Courtney-Barrer, B.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Blanco, L.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Brucalassi, A.
    INAF Arcetri Osservatorio, Largo E Fermi 5, I-50125 Florence, Italy..
    Cumani, C.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Follert, R.
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Haimerl, A.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Hatzes, A.
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Haug, M.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Hinterschuster, R.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Hubin, N.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Ives, D. J.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Jung, Y.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Jones, M.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Kaeufl, H. -u.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Kirchbauer, J. -p.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Klein, B.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Korhonen, H. H.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Koehler, J.
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Lizon, J-l.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Moins, C.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Molina-Conde, I.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Marquart, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Neeser, M.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Oliva, E.
    INAF Arcetri Osservatorio, Largo E Fermi 5, I-50125 Florence, Italy..
    Pallanca, L.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Pasquini, L.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Paufique, J.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Reiners, A.
    Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Schneller, D.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Schmutzer, R.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Seemann, U.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Slumstrup, D.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Smette, A.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Stegmeier, J.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Stempels, Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Tordo, S.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Valenti, E.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Valenzuela, J. J.
    European Southern Observ, Alonso Cordova 3107, Santiago, Vitacura, Chile..
    Vernet, J.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Vinther, J.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Wehrhahn, Ansgar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    CRIRES+ on sky at the ESO Very Large Telescope: Observing the Universe at infrared wavelengths and high spectral resolution2023In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 671, article id A24Article in journal (Refereed)
    Abstract [en]

    The CRyogenic InfraRed Echelle Spectrograph (CRIRES) Upgrade project CRIRES+ extended the capabilities of CRIRES. It transformed this VLT instrument into a cross-dispersed spectrograph to increase the wavelength range that is covered simultaneously by up to a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 mu m cutoff wavelength replaced the existing detectors. Amongst many other improvements, a new spectropolarimetric unit was added and the calibration system has been enhanced. The instrument was installed at the VLT on Unit Telescope 3 at the beginning of 2020 and successfully commissioned and verified for science operations during 2021, partly remotely from Europe due to the COVID-19 pandemic. The instrument was subsequently offered to the community from October 2021 onwards. This article describes the performance and capabilities of the upgraded instrument and presents on sky results.

    Download full text (pdf)
    fulltext
  • 24.
    Dorn, Reinhold J.
    et al.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Bristow, Paul
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Smoker, Jonathan
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Rodler, Florian
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Accardo, Matteo
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Van den Ancker, Mario
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Baruffolo, Andrea
    INAF Osservatorio Astronomico Padova, Padua, Italy..
    Courtney-Barrer, Benjamin
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Blanco, Leonardo
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Brucalassi, Anna
    INAF Arcetri Osservatorio, Largo Fermi 5, I-50125 Florence, Italy..
    Cumani, Claudio
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Haimerl, Andreas
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Hatzes, Artie
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Haug, Marcus
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Heiter, Ulrike
    Hinterschuster, Renate
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Hubin, Norbert
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Ives, Derek J.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Jung, Yves
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Jones, Matias
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Kirchbauer, Jean Paul
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Klein, Barbara
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Korhonen, Heidi Helena
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Koehler, Jana
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Lavail, Alexis
    Lizon, Jean Louis
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Moins, Christophe
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Molina-Conde, Ignacio
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Marquart, Thomas
    Oliva, Ernesto
    Pallanca, Laurent
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Pasquini, Luca
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Paufique, Jerome
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Reiners, Ansgar
    Univ Gottingen, Inst Astrophysik, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Schneller, Dominik
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Schmutzer, Ricardo
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Seemann, Ulf
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Slumstrup, Ditte
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Smette, Alain
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Stegmeier, Joerg
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Stempels, Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Tordo, Sebastien
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Valenti, Elena
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    Valenzuela, Jose Javier
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Vernet, Joel
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Munich, Germany..
    CRIRES+ on sky: High spectral resolution at infrared wavelength enabling better science at the ESO VLT2022In: Ground-Based And Airborne Instrumentation For Astronomy IX / [ed] Evans, CJ, Bryant, JJ, Motohara, K, SPIE - International Society for Optical Engineering, 2022, Vol. 12184, article id 121841FConference paper (Refereed)
    Abstract [en]

    CRIRES+ extended the capabilities of CRIRES, the CRyogenic InfraRed Echelle Spectrograph. It transformed this VLT instrument into a cross-dispersed spectrograph to increase the wavelength range that is covered simultaneously by a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 mu m cut-off wavelength replaced the existing detectors. Amongst many other improvements a new spectropolarimetric unit was added and the calibration system has been enhanced. The instrument was installed at the VLT on Unit Telescope 3 beginning of 2020 and successfully commissioned and verified for science operations during 2021, partly remote from Europe due to the pandemic. The instrument was subsequently offered to the community from October 2021 onwards. This article describes the performance and capabilities of this development and presents on sky results.

  • 25.
    Dorn, Reinhold J.
    et al.
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Follert, Roman
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Bristow, Paul
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Cumani, Claudio
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Eschbaumer, Siegfried
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Grunhut, Jason
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Haimerl, Andreas
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Hatzes, Artie
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Hinterschuster, Renate
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Ives, Derek J.
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Jung, Yves
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Kerber, Florian
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Klein, Barbara
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Lavail, Alexis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Lizon, Jean Louis
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Loewinger, Tom
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Molina-Conde, Ignacio
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Nicholson, Belinda
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Marquart, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Oliva, Ernesto
    INAF Arcetri Osservatorio, Largo E Fermi 5, I-50125 Florence, Italy..
    Origlia, Livia
    INAF Bologna Observ, Via Ranzani 1, I-40127 Bologna, Italy..
    Pasquini, Luca
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Paufique, Jerome
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Reiners, Ansgar
    Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Seemann, Ulf
    Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Stegmeier, Jorg
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Stempels, Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Tordo, Sebastien
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    The " plus " for CRIRES: enabling better science at infrared wavelength and high spectral resolution at the ESO VLT2016In: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY VI / [ed] Christopher J Evans, 2016, Vol. 9908, article id 99080IConference paper (Refereed)
    Abstract [en]

    The adaptive optics (AO) assisted CRIRES instrument was a IR (0.92 - 5.2 mu m) high-resolution spectrograph in operation from 2006 to 2014 at the Very Large Telescope (VLT) observatory. CRIRES was a unique instrument, accessing a parameter space (wavelength range and spectral resolution) up to now largely uncharted. It consisted of a single-order spectrograph providing long-slit (40 arcsecond) spectroscopy with a resolving power up to R=100 000. However the setup was limited to a narrow, single-shot, spectral range of about 1/70 of the central wavelength, resulting in low observing efficiency for many scientific programmes requiring a broad spectral coverage. The CRIRES upgrade project, CRIRES, transfouns this VLT instrument into a cross-dispersed spectrograph to increase the simultaneously covered wavelength range by a factor of ten. A new and larger detector focal plane array of three Hawaii 2RG detectors with 5.3 mu m cut-off wavelength will replace the existing detectors. For advanced wavelength calibration, custom-made absorption gas cells and an etalon system will be added. A spectro-polarimetric unit will allow the recording of circular and linear polarized spectra. This upgrade will be supported by dedicated data reduction software allowing the community to take full advantage of the new capabilities. CRIRES has now entered its assembly and integration phase and will return with all new capabilities by the beginning of 2018 to the Very Large Telescope in Chile. This article will provide the reader with an update of the current status of the instrument as well as the remaining steps until final installation at the Paranal Observatory.

  • 26.
    Dorval, Patrick
    et al.
    Leiden Univ, Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands.
    Snik, Frans
    Leiden Univ, Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Navarro, Ramon
    NOVA, Opt IR Instrumentat Grp ASTRON, POB 2, NL-7990 AA Dwingeloo, Netherlands.
    Kragt, Jan
    NOVA, Opt IR Instrumentat Grp ASTRON, POB 2, NL-7990 AA Dwingeloo, Netherlands.
    ter Horst, Rik
    NOVA, Opt IR Instrumentat Grp ASTRON, POB 2, NL-7990 AA Dwingeloo, Netherlands.
    Kunst, Peter
    NOVA, Opt IR Instrumentat Grp ASTRON, POB 2, NL-7990 AA Dwingeloo, Netherlands.
    Snellen, Ignas
    Leiden Univ, Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands.
    Naylor, Tim
    Univ Exeter, Dept Phys & Astron, Stocker Rd, Exeter EX4 4QL, Devon, England.
    Thompson, Samantha
    Univ Cambridge, Astrophys Grp, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Analysis of the polarimetric performance of the HARPS3 Cassegrain adaptor unit2018In: Ground-Based And Airborne Instrumentation For Astronomy VII / [ed] Evans, CJ Simard, L Takami, H, 2018, article id UNSP 107026BConference paper (Refereed)
    Abstract [en]

    The third version of the High Accuracy Radial velocity Planet Searcher (HARPS3) instrument is built for a ten-year programme aimed at achieving 10 cm/sec radial velocity precision on nearby stars to search for Earth-like planets. HARPS3 will be commissioned on the to-be-roboticized 2.54-m Isaac Newton Telescope at La Palma in 2021. One of the main changes compared to its predecessors is the novel dual-beam Cassegrain focus, featuring a stabilised beam feed into the HARPS3 spectrograph and an insertable polarimetric sub-unit. This polarimetric sub-unit enables HARPS3 to directly measure stellar activity signatures, which can be useful for correcting activity-induced radial velocity jitter in the search for Earth-like planets. The sub-unit consists of superachromatic polymer quarter- and half-wave retarders for circular and linear polarizations respectively, designed to suppress polarized fringing, and a novel polarimetric beam splitter based on a wire-grid design, separating the two polarimetric beams by 30 mm and feeding two separate science fibers. The dual-beam exchange implementation in combination with the extreme stability of the HARPS3 spectrograph enables a polarimetric sensitivity of 10(-5) on bright stars. One of the main challenges of such a system is in the characterization of instrumental polarization effects which limit the polarimetric accuracy of the polarimetric observing mode. By design and characterization of this subsystem and by pre-emptively mitigating possible noise sources, we can minimize the noise characteristics of the polarization sub-unit to allow for precise observations. In this paper we report on the design, realization, assembly, alignment, and testing of the polarimetric unit to be installed in the Cassegrain Adaptor Unit of the HARPS3 spectrograph.

  • 27.
    Dubernet, M. L.
    et al.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Antony, B. K.
    Indian Sch Mines, Dept Appl Phys, Dhanbad 826004, Bihar, India..
    Ba, Y. A.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Babikov, Yu L.
    Russian Acad Sci, Inst Atmospher Opt, Zuev Sq 1, Tomsk 634021, Russia.;Tomsk State Univ, Tomsk 634050, Russia..
    Bartschat, K.
    Drake Univ, Dept Phys & Astron, Des Moines, IA 50311 USA..
    Boudon, V.
    Univ Bourgogne Franche Comte, CNRS, UMR 6303, Lab Interdisciplinaire Carnot Bourgogne, 9 Ave Alain Savary,BP 47 870, F-21078 Dijon, France..
    Braams, B. J.
    IAEA, Vienna Int Ctr, Div Phys & Chem Sci, Nucl Data Sect, A-1400 Vienna, Austria..
    Chung, H-K
    IAEA, Vienna Int Ctr, Div Phys & Chem Sci, Nucl Data Sect, A-1400 Vienna, Austria..
    Daniel, F.
    Univ Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France..
    Delahaye, F.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Del Zanna, G.
    Ctr Math Sci, DAMTP, Wilberforce Rd, Cambridge CB3 0WA, England..
    de Urquijo, J.
    Univ Nacl Autonoma Mexico, Inst Ciencias Fis, POB 48-3, Cuernavaca 62251, Morelos, Mexico..
    Dimitrijevic, M. S.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France.;Astron Observ, Volgina 7, Belgrade 11060, Serbia..
    Domaracka, A.
    UCN, ENSICAEN, CNRS, CIMAP,UMR 6252,CEA, Bd Henri Becquerel,BP 5133, F-14070 Caen 5, France..
    Doronin, M.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Drouin, B. J.
    CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Endres, C. P.
    Max Planck Inst Extraterr Phys, Giessenbachstr, D-85748 Garching, Germany..
    Fazliev, A. Z.
    Russian Acad Sci, Inst Atmospher Opt, Zuev Sq 1, Tomsk 634021, Russia..
    Gagarin, S. V.
    Russian Fed Nucl Ctr All Russian Inst Tech Phys R, Snezhinsk, Russia..
    Gordon, I. E.
    Harvard Smithsonian Ctr Astrophys, Atom & Mol Phys Div, MS50,60 Garden St, Cambridge, MA 02138 USA..
    Gratier, P.
    Univ Bordeaux, LAB, UMR 5804, F-33270 Florac, France.;CNRS, LAB, UMR 5804, F-33270 Florac, France..
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Hill, C.
    UCL, Dept Phys & Astron, Mortimer St, London WC1E 6BT, England..
    Jevremovic, D.
    Astron Observ, Volgina 7, Belgrade 11060, Serbia..
    Joblin, C.
    Univ Toulouse, UPS OMP, CNRS, Inst Rech Astrophys & Planetol, 9 Av Colonel Roche, F-31028 Toulouse 4, France..
    Kasprzak, A.
    Observ Paris, SRCV, 61 Av Denfert Rochereau, F-75014 Paris, France..
    Krishnakumar, E.
    Tata Inst Fundamental Res, Dept Nucl & Atom Phys, Homi Bhabha Rd, Bombay 400005, Maharashtra, India..
    Leto, G.
    INAF Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy..
    Loboda, P. A.
    Russian Fed Nucl Ctr All Russian Inst Tech Phys R, Snezhinsk, Russia.;Natl Res Nucl Univ, Moscow Engn Phys Inst MEPhI, Moscow, Russia..
    Louge, T.
    Univ Toulouse, UPS OMP, CNRS, Inst Rech Astrophys & Planetol, 9 Av Colonel Roche, F-31028 Toulouse 4, France..
    Maclot, S.
    UCN, ENSICAEN, CNRS, CIMAP,UMR 6252,CEA, Bd Henri Becquerel,BP 5133, F-14070 Caen 5, France.;Univ Caen Normandie, Esplanade Paix, CS 14032, F-14032 Caen 5, France..
    Marinkovic, B. P.
    Univ Belgrade, Inst Phys Belgrade, POB 57, Belgrade 11001, Serbia..
    Markwick, A.
    Univ Manchester, Sch Phys & Astron, Jodrell Bank Ctr Astrophys, Oxford Rd, Manchester M13 9PL, Lancs, England..
    Marquart, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Mason, H. E.
    Ctr Math Sci, DAMTP, Wilberforce Rd, Cambridge CB3 0WA, England..
    Mason, N. J.
    Open Univ, Dept Phys Sci, Walton Hall, Milton Keynes MK7 6AA, Bucks, England..
    Mendoza, C.
    IVIC, Ctr Fis, POB 20632, Caracas 1020A, Venezuela..
    Mihajlov, A. A.
    Univ Belgrade, Inst Phys Belgrade, POB 57, Belgrade 11001, Serbia..
    Millar, T. J.
    Queens Univ Belfast, Sch Math & Phys, Univ Rd, Belfast BT7 1NN, Antrim, North Ireland..
    Moreau, N.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Mulas, G.
    Univ Toulouse, UPS OMP, CNRS, Inst Rech Astrophys & Planetol, 9 Av Colonel Roche, F-31028 Toulouse 4, France.;Osservatorio Astron Cagliari, Ist Nazl AstroFis, Via Sci 5, I-09047 Selargius, CA, Italy..
    Pakhomov, Yu
    RAS, Inst Astron, Pyatnitskaya 48, Moscow 119017, Russia..
    Palmeri, P.
    Univ Mons, Phys Atom & Astrophys, B-7000 Mons, Belgium..
    Pancheshnyi, S.
    ABB Corp Res, Segelhofstr 1K, CH-5405 Baden, Switzerland..
    Perevalov, V. I.
    Russian Acad Sci, Inst Atmospher Opt, Zuev Sq 1, Tomsk 634021, Russia..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Postler, J.
    Univ Innsbruck, Inst Ion Phys & Appl Phys, Technikerstr 25-3, A-6020 Innsbruck, Austria..
    Quinet, P.
    Univ Mons, Phys Atom & Astrophys, B-7000 Mons, Belgium.;Univ Liege, IPNAS, B-4000 Liege, Belgium..
    Quintas-Sanchez, E.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Ralchenko, Yu
    NIST, Atom Spect Grp, Gaithersburg, MD 20899 USA..
    Rhee, Y-J
    Korea Atom Energy Res Inst, Nucl Data Ctr, Taejon 305353, South Korea..
    Rixon, G.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Rothman, L. S.
    Harvard Smithsonian Ctr Astrophys, Atom & Mol Phys Div, MS50,60 Garden St, Cambridge, MA 02138 USA..
    Roueff, E.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Ryabchikova, T.
    RAS, Inst Astron, Pyatnitskaya 48, Moscow 119017, Russia..
    Sahal-Brechot, S.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Scheier, P.
    Univ Innsbruck, Inst Ion Phys & Appl Phys, Technikerstr 25-3, A-6020 Innsbruck, Austria..
    Schlemmer, S.
    Univ Cologne, Inst Phys 1, zulpicher Str 77, D-50937 Kln, Germany..
    Schmitt, B.
    Univ Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France..
    Stempels, Eric H. C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Tashkun, S.
    Russian Acad Sci, Inst Atmospher Opt, Zuev Sq 1, Tomsk 634021, Russia..
    Tennyson, J.
    UCL, Dept Phys & Astron, Mortimer St, London WC1E 6BT, England..
    Tyuterev, Vl G.
    Univ Reims, GSMA, UMR CNRS 7331, Reims, France..
    Vujcic, V.
    Astron Observ, Volgina 7, Belgrade 11060, Serbia.;Univ Belgrade, Fac Org Sci, Jove Ilica 33, Belgrade 11000, Serbia..
    Wakelam, V.
    Univ Bordeaux, LAB, UMR 5804, F-33270 Florac, France.;CNRS, LAB, UMR 5804, F-33270 Florac, France..
    Walton, N. A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Zatsarinny, O.
    Drake Univ, Dept Phys & Astron, Des Moines, IA 50311 USA..
    Zeippen, C. J.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Zwoelf, C. M.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    The virtual atomic and molecular data centre (VAMDC) consortium2016In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 49, no 7, article id 074003Article in journal (Refereed)
    Abstract [en]

    The Virtual Atomic and Molecular Data Centre (VAMDC) Consortium is a worldwide consortium which federates atomic and molecular databases through an e-science infrastructure and an organisation to support this activity. About 90% of the inter-connected databases handle data that are used for the interpretation of astronomical spectra and for modelling in many fields of astrophysics. Recently the VAMDC Consortium has connected databases from the radiation damage and the plasma communities, as well as promoting the publication of data from Indian institutes. This paper describes how the VAMDC Consortium is organised for the optimal distribution of atomic and molecular data for scientific research. It is noted that the VAMDC Consortium strongly advocates that authors of research papers using data cite the original experimental and theoretical papers as well as the relevant databases.

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    fulltext
  • 28. Fischer, Debra A.
    et al.
    Gaidos, Eric
    Howard, Andrew W.
    Giguere, Matthew J.
    Johnson, John A.
    Marcy, Geoffrey W.
    Wright, Jason T.
    Valenti, Jeff A.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Clubb, Kelsey I.
    Isaacson, Howard
    Apps, Kevin
    Lepine, Sebastien
    Mann, Andrew
    Moriarty, John
    Brewer, John
    Spronck, Julien F. P.
    Schwab, Christian
    Szymkowiak, Andrew
    M2K. II. A Triple-Planet System Orbiting Hip 572742012In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 745, no 1, p. 21-Article in journal (Refereed)
    Abstract [en]

    Doppler observations from Keck Observatory have revealed a triple-planet system orbiting the nearby K4V star, HIP 57274. The inner planet, HIP 57274b, is a super-Earth with M sin i = 11.6 M-circle plus (0.036 M-Jup), an orbital period of 8.135 +/- 0.004 days, and slightly eccentric orbit e = 0.19 +/- 0.1. We calculate a transit probability of 6.5% for the inner planet. The second planet has M sin i = 0.4 M-Jup with an orbital period of 32.0 +/- 0.02 days in a nearly circular orbit (e = 0.05 +/- 0.03). The third planet has M sin i = 0.53 M-Jup with an orbital period of 432 +/- 8 days (1.18 years) and an eccentricity e = 0.23 +/- 0.03. This discovery adds to the number of super-Earth mass planets with M sin i < 12 M-circle plus that have been detected with Doppler surveys. We find that 56% +/- 18% of super-Earths are members of multi-planet systems. This is certainly a lower limit because of observational detectability limits, yet significantly higher than the fraction of Jupiter mass exoplanets, 20% +/- 8%, that are members of Doppler-detected, multi-planet systems.

  • 29. Follert, R.
    et al.
    Dorn, R. J.
    Oliva, E.
    Lizon, J. L.
    Hatzes, A.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Reiners, A.
    Seemann, U.
    Stempels, Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Heiter, Ulrike
    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.
    Lockhart, Matthew
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Anglada-Escude, G.
    Loewinger, T.
    Baade, D.
    Grunhut, J.
    Bristow, P.
    Klein, B.
    Jung, Y.
    Ives, D. J.
    Kerber, F.
    Pozna, E.
    Paufique, J.
    Kaeufl, H. U.
    Origlia, L.
    Valenti, E.
    Gojak, D.
    Hilker, M.
    Pasquini, L.
    Smette, A.
    Smoker, J.
    CRIRES plus: a cross-dispersed high-resolution infrared spectrograph for the ESO VLT2014In: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V, 2014, Vol. 9147, article id 914719Conference paper (Refereed)
    Abstract [en]

    High-resolution infrared spectroscopy plays an important role in astrophysics from the search for exoplanets to cosmology. Yet, many existing infrared spectrographs are limited by a rather small simultaneous wavelength coverage. The AO assisted CRIRES instrument, installed at the ESO VLT on Paranal, is one of the few IR (0.92-5.2 mu m) high-resolution spectrographs in operation since 2006. However it has a limitation that hampers its efficient use: the wavelength range covered in a single exposure is limited to similar to 15 nanometers. The CRIRES Upgrade project (CRIRES+) will transform CRIRES into a cross-dispersed spectrograph and will also add new capabilities. By introducing cross-dispersion elements the simultaneously covered wavelength range will be increased by at least a factor of 10 with respect to the present configuration, while the operational wavelength range will be preserved. For advanced wavelength calibration, new custom made absorption gas cells and etalons will be added. A spectro-polarimetric unit will allow one for the first time to record circularly polarized spectra at the highest spectral resolution. This will be all supported by a new data reduction software which will allow the community to take full advantage of the new capabilities of CRIRES+.

  • 30.
    Follert, Roman
    et al.
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Taubert, Dieter
    Phys Tech Bundesanstalt, Fachbereich Detektorradiometrie & Strahlungstherm, Abbestr 2-12, D-10587 Berlin, Germany..
    Hollandt, Joerg
    Phys Tech Bundesanstalt, Fachbereich Detektorradiometrie & Strahlungstherm, Abbestr 2-12, D-10587 Berlin, Germany..
    Monte, Christian
    Phys Tech Bundesanstalt, Fachbereich Detektorradiometrie & Strahlungstherm, Abbestr 2-12, D-10587 Berlin, Germany..
    Oliva, Ernesto
    INAF Osservatori Arcetri, Largo E Fermi 5, I-50125 Florence, Italy..
    Seemann, Ulf
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Loewinger, Tom
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Anwand-Heerwart, Heiko
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Schmidt, Christof
    Georg August Univ Gottingen, Zent Werkstatt Fak Phys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Dorn, Reinhold J.
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Bristow, Paul
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Hatzes, Artie
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Reiners, Ansgar
    Georg August Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Stempels, Eric
    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.
    Lavail, Alexis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Cumani, Claudio
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Grunhut, Jason
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Haimerl, Andreas
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Hinterschuster, Renate
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Ives, Derek J.
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Jung, Yves
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Kerber, Florian
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Klein, Barbara
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Lizon, Jean Louis
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Molina-Conde, Ignacio
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Nicholson, Belinda
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Origlia, Livia
    INAF Osservatorio Bologna, Via Ranzani 1, I-40127 Bologna, Italy..
    Pasquini, Luca
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Paufique, Jerome
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Stegmeier, Joerg
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Tordo, Sebastien
    European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Characterizing the cross dispersion reflection gratings of CRIRES2016In: Advances In Optical And Mechanical Technologies For Telescopes And Instrumentation Ii, 2016, article id UNSP 99122BConference paper (Refereed)
    Abstract [en]

    The CRIRES+ project attempts to upgrade the CRIRES instrument into a cross dispersed echelle spectrograph with a simultaneous recording of 8-10 diffraction orders. In order to transform the CRIRES spectrograph into a cross-dispersing instrument, a set of six reflection gratings, each one optimized for one of the wavelength bands CRIRES+ will operate in (YJHKLM), will be used as cross dispersion elements in CRIRES+. Due to the upgrade nature of the project, the choice of gratings depends on the fixed geometry of the instrument. Thus, custom made gratings would be required to achieve the ambitious design goals. Custom made gratings have the disadvantage, though, that they come at an extraordinary price and with lead times of more than 12 months. To mitigate this, a set of off-the-shelf gratings was obtained which had grating parameters very close to the ones being identified as optimal. To ensure that the rigorous specifications for CRIRES+ will be fulfilled, the CRIRES+ team started a collaboration with the Physikalisch-Technische Bundesanstalt Berlin (PTB) to characterize gratings under conditions similar to the operating conditions in CRIRES+ (angle of incidence, wavelength range). The respective test setup was designed in collaboration between PTB and the CRIRES+ consortium. The PTB provided optical radiation sources and calibrated detectors for each wavelength range. With this setup, it is possible to measure the absolute efficiency of the gratings both wavelength dependent and polarization state dependent in a wavelength range from 0.9 mu m to 6 mu m.

  • 31.
    Hackman, T.
    et al.
    Univ Helsinki, Dept Phys, POB 64, Helsinki 00014, Finland.
    Ilyin, I.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany.
    Lehtinen, J. J.
    Max Planck Inst Solar Syst Res, Justus von Liebig Weg 3, D-37077 Gottingen, Germany;Aalto Univ, ReSoLVE Ctr Excellence, Dept Comp Sci, POB 15400, Aalto 00076, Finland.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Kaepylae, M. J.
    Max Planck Inst Solar Syst Res, Justus von Liebig Weg 3, D-37077 Gottingen, Germany;Aalto Univ, ReSoLVE Ctr Excellence, Dept Comp Sci, POB 15400, Aalto 00076, Finland.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Willamo, T.
    Univ Helsinki, Dept Phys, POB 64, Helsinki 00014, Finland.
    Starspot activity of HD199178 Doppler images from 1994-20172019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 625, article id A79Article in journal (Refereed)
    Abstract [en]

    Context

    Studying the spots of late-type stars is crucial for distinguishing between the various proposed dynamo mechanisms believed to be the main cause of starspot activity. For this research it is important to collect observation time series that are long enough to unravel both long- and short-term spot evolution. Doppler imaging is a very efficient method for studying spots of stars that cannot be angularly resolved. Aims. High-resolution spectral observations during 1994-2017 are analysed in order to reveal long- and short-term changes in the spot activity of the FK Comae-type subgiant HD199178.

    Methods

    Most of the observations were collected with the Nordic Optical Telescope. The Doppler imaging temperature maps were calculated using an inversion technique based on Tikhonov regularisation and utilising multiple spectral lines.

    Results

    We present a unique series of 41 temperature maps spanning more than 23 years. All reliable images show a large cool spot region centred near the visible rotation pole. Some lower latitude cool features are also recovered, although the reliability of these is questionable. There is an expected anti-correlation between the mean surface temperature and the spot coverage. Using the Doppler images, we construct the equivalent of a solar butterfly diagram for HD199178.

    Conclusions

    HD199178 clearly has a long-term large and cool spot structure at the rotational pole. This spot structure dominated the spot activity during the years 1994-2017. The size and position of the structure has evolved with time, with a gradual increase during the last years. The lack of lower latitude features prevents the determination of a possible differential rotation.

  • 32. Hackman, T.
    et al.
    Mantere, M. J.
    Jetsu, L.
    Ilyin, I.
    Kajatkari, P.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Lehtinen, J.
    Lindborg, M.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Tuominen, I.
    Spot activity of II Peg2011In: Astronomical Notes - Astronomische Nachrichten, ISSN 0004-6337, E-ISSN 1521-3994, Vol. 332, no 9-10, p. 859-865Article in journal (Refereed)
    Abstract [en]

    We have studied the long-term spot activity of the RS CVn star II Peg by means of Doppler imaging based on spectroscopy and time series analysis of photometry. We present 28 Doppler imaging temperature maps spanning the years 1994-2010, of which 14 were calculated for the present study. The longitudinal spot distribution, derived from the surface temperature maps, is compared with epochs of the light curve minima, derived from photometric observations. We detect a longitudinal drift in the major spot structure during 1995-2003. After this there is a clear decrease in the activity level and no clear drift can be seen. We conclude that the variations could be caused by a cyclic behaviour of the underlying magnetic dynamo.

  • 33. Hackman, T.
    et al.
    Mantere, M. J.
    Lindborg, M.
    Ilyin, I.
    Kochukhov, Oleg
    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.
    Tuominen, I.
    Doppler images of II Pegasi for 2004-20102012In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 538, p. A126-Article in journal (Refereed)
    Abstract [en]

    Aims. We study the spot activity of II Peg during the years 2004-2010 to determine long- and short-term changes in the magnetic activity. In a previous study, we detected a persistent active longitude, as well as major changes in the spot configuration occurring on a timescale of shorter than a year. The main objective of this study is to determine whether the same phenomena persist in the star during these six years of spectroscopic monitoring. Methods. The observations were collected with the high-resolution SOFIN spectrograph at the Nordic Optical Telescope. The temperature maps were calculated using a Doppler imaging code based on Tikhonov regularization. Results. We present 12 new temperature maps that show spots distributed mainly over high and intermediate latitudes. In each image, 1-3 main active regions can be identified. The activity level of the star is clearly lower than during our previous study for the years 1994-2002. In contrast to the previous observations, we detect no clear drift of the active regions with respect to the rotation of the star. Conclusions. Having shown a systematic longitudinal drift of the spot-generating mechanism during 1994-2002, the star has clearly switched to a low-activity state for 2004-2010, during which the spot locations appear more random over phase space. It could be that the star is near to a minimum of its activity cycle.

  • 34.
    Hahlin, Axel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Rains, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Lavail, Alexis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Univ Toulouse, Inst Rech Astrophys & Planetol, CNRS, IRAP,UMR 5277, 14 Ave Edouard Belin, F-31400 Toulouse, France..
    Hatzes, A.
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Reiners, A.
    Georg August Univ, Inst Astrophys & Geophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Seemann, U.
    Georg August Univ, Inst Astrophys & Geophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.;European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Boldt-Christmas, Linn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Guenther, E. W.
    Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany..
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Nortmann, L.
    Georg August Univ, Inst Astrophys & Geophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany..
    Yan, F.
    Univ Sci & Technol China, Dept Astron, 96 JinZhai Rd, Hefei 230026, Anhui, Peoples R China..
    Shulyak, D.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, Granada 18008, Spain..
    Smoker, J. V.
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile.;Royal Observ, UK Astron Technol Ctr, Blackford Hill, Edinburgh EH9 3HJ, Scotland..
    Rodler, F.
    European Southern Observ, Alonso Cordova 3107, Santiago, Chile..
    Bristow, P.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Dorn, R. J.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Jung, Y.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Marquart, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Stempels, H. C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Determination of small-scale magnetic fields on Sun-like stars in the near-infrared using CRIRES+2023In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 675, article id A91Article in journal (Refereed)
    Abstract [en]

    Aims: We aim to characterise the small-scale magnetic fields of a sample of 16 Sun-like stars and investigate the capabilities of the newly upgraded near-infrared (NIR) instrument CRIRES+ at the Very Large Telescope in the context of small-scale magnetic field studies. Our targets also had their magnetic fields studied with optical spectra, which allowed us to compare magnetic field properties at different spatial scales on the stellar surface and to contrast small-scale magnetic field measurements at different wavelengths.

    Methods: We analysed the Zeeman broadening signature for six magnetically sensitive and insensitive Fe I lines in the H-band to measure small-scale magnetic fields on the stellar surfaces of our sample. We used polarised radiative transfer modelling and non-local thermodynamic equilibrium departure coefficients in combination with Markov chain Monte Carlo sampling to determine magnetic field characteristics and non-magnetic stellar parameters. We used two different approaches to describe the small-scale magnetic fields. The first is a two-component model with a single magnetic region and a free magnetic field strength. The second model contains multiple magnetic components with fixed magnetic field strengths.

    Results: We found average magnetic field strengths ranging from & SIM;0.4 kG down to < 0.1 kG. The results align closely with other results from high-resolution NIR spectrographs, such as SPIRou. It appears that the typical magnetic field strength in the magnetic region is slightly stronger than 1.3 kG, and for most stars in our sample, this strength is between 1 and 2 kG. We also found that the small-scale fields correlate with the large-scale fields and that the small-scale fields are at least ten times stronger than the large-scale fields inferred with Zeeman Doppler imaging. The two- and multi-component models produce systematically different results, as the strong fields from the multi-component model increase the obtained mean magnetic field strength. When comparing our results with the optical measurements of small-scale fields, we found a systematic offset two to three times stronger than fields in the optical results. This discrepancy cannot be explained by uncertainties in stellar parameters. Care should therefore be taken when comparing results obtained at different wavelengths until a clear cause can be established.

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  • 35.
    Heiter, Ulrike
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Barklem, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Fossati, L.
    Kildiyarova, R.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Kupka, F.
    Obbrugger, M.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Plez, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ryabchikova, T.
    Stempels, H. C.
    Stütz, C.
    Weiss, W. W.
    VALD — an atomic and molecular database for astrophysics2008In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 130, p. 012011-Article in journal (Refereed)
    Abstract [en]

    The VALD database of atomic and molecular data aims to ensure a robust and consistent analysis of astrophysical spectra. We offer a convenient e-mail and web-based user interface to a vast collection of spectral line parameters for all chemical elements and in the future also for molecules. An international team is working on the following tasks: collecting line parameters from relevant theoretical and experimental publications, computing line parameters, evaluating the data quality by comparison of similar data from different sources and by comparison with astrophysical observations, and incorporating the data into VALD. A unique feature of VALD is its capability to provide the most comprehensive spectral line lists for specific astrophysical plasma conditions defined by the user.

  • 36.
    Heiter, Ulrike
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Gustafsson, Bengt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Jordi, C.
    Carrasco, J. M.
    Cool stars in the Gaia photometric system2005In: 13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, 2005, p. 635-Conference paper (Other scientific)
  • 37. Howard, Andrew W.
    et al.
    Johnson, John Asher
    Marcy, Geoffrey W.
    Fischer, Debra A.
    Wright, Jason T.
    Henry, Gregory W.
    Giguere, Matthew J.
    Isaacson, Howard
    Valenti, Jeff A.
    Anderson, Jay
    Piskunov, Nikolai E.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    THE NASA-UC ETA-EARTH PROGRAM:  I. A SUPER-EARTH ORBITING HD 79242009In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 696, no 1, p. 75-83Article in journal (Refereed)
    Abstract [en]

    We report the discovery of the first low-mass planet to emerge from the NASA-UC Eta-Earth Program, a super-Earth orbiting the K0 dwarf HD 7924. Keplerian modeling of precise Doppler radial velocities reveals a planet with minimum mass M-P sin i = 9.26M(circle plus) in a P = 5.398 d orbit. Based on Keck-HIRES measurements from 2001 to 2008, the planet is robustly detected with an estimated false alarm probability of less than 0.001. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 7924 is photometrically constant over the radial velocity period to 0.19 mmag, supporting the existence of the planetary companion. No transits were detected down to a photometric limit of similar to 0.5 mmag, eliminating transiting planets with a variety of compositions. HD 7924b is one of only eight planets detected by the radial velocity technique with M-P sini < 10 M-circle plus and as such is a member of an emerging family of low-mass planets that together constrain theories of planet formation.

  • 38. Howard, Andrew W.
    et al.
    Johnson, John Asher
    Marcy, Geoffrey W.
    Fischer, Debra A.
    Wright, Jason T.
    Henry, Gregory W.
    Isaacson, Howard
    Valenti, Jeff A.
    Anderson, Jay
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    The NASA-UC Eia-earth program. II. a planet orbiting HD 156668 with a minimum mass of four earth masses2011In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 726, no 2, p. 73-Article in journal (Refereed)
    Abstract [en]

    We report the discovery of HD 156668 b, an extrasolar planet with a minimum mass of M-P sin i = 4.15 M-circle plus. This planet was discovered through Keplerian modeling of precise radial velocities from Keck-HIRES and is the second super-Earth to emerge from the NASA-UC Eta-Earth Survey. The best-fit orbit is consistent with circular and has a period of P = 4.6455 days. The Doppler semi-amplitude of this planet, K = 1.89 m s(-1), is among the lowest ever detected, on par with the detection of GJ 581 e using HARPS. A longer period (P approximate to 2.3 years), low-amplitude signal of unknown origin was also detected in the radial velocities and was filtered out of the data while fitting the short-period planet. Additional data are required to determine if the long-period signal is due to a second planet, stellar activity, or another source. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 156668 (an old, quiet K3 dwarf) is photometrically constant over the radial velocity period to 0.1 mmag, supporting the existence of the planet. No transits were detected down to a photometric limit of similar to 3 mmag, ruling out transiting planets dominated by extremely bloated atmospheres, but not precluding a transiting solid/liquid planet with a modest atmosphere.

  • 39. Howard, Andrew W.
    et al.
    Johnson, John Asher
    Marcy, Geoffrey W.
    Fischer, Debra A.
    Wright, Jason T.
    Henry, Gregory W.
    Isaacson, Howard
    Valenti, Jeff A.
    Anderson, Jay
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    THE NASA-UC ETA-EARTH PROGRAM. III. A SUPER-EARTH ORBITING HD 97658 AND A NEPTUNE-MASS PLANET ORBITING G1 7852011In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 730, no 1, p. 10-Article in journal (Refereed)
    Abstract [en]

    We report the discovery of planets orbiting two bright, nearby early K dwarf stars, HD 97658 and G1 785. These planets were detected by Keplerian modeling of radial velocities measured with Keck-HIRES for the NASA-UC Eta-Earth Survey. HD 97658 b is a close-in super-Earth with minimum mass M sin i = 8.2 +/- 1.2 M-circle plus, orbital period P = 9.494 +/- 0.005 days, and an orbit that is consistent with circular. G1 785 b is a Neptune-mass planet with M sin i = 21.6 +/- 2.0 M-circle plus, P = 74.39 +/- 0.12 days, and orbital eccentricity e = 0.30 +/- 0.09. Photometric observations with the T12 0.8 m automatic photometric telescope at Fairborn Observatory show that HD 97658 is photometrically constant at the radial velocity period to 0.09 mmag, supporting the existence of the planet.

  • 40. Johns-Krull, Christopher M.
    et al.
    Chen, Wei
    Valenti, Jeff A.
    Jeffers, Sandra V.
    Piskunov, Nikolai E.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Makaganiuk, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Stempels, Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Snik, Frans
    Keller, Christoph
    Rodenhuis, M.
    Magnetically Controlled Accretion on the Classical T Tauri Stars GQ Lupi and TW Hydrae2013In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 765, no 1, p. 11-Article in journal (Refereed)
    Abstract [en]

    We present high spectral resolution (R approximate to 108,000) Stokes V polarimetry of the classical T Tauri stars (CTTSs) GQ Lup and TW Hya obtained with the polarimetric upgrade to the HARPS spectrometer on the ESO 3.6 m telescope. We present data on both photospheric lines and emission lines, concentrating our discussion on the polarization properties of the He I emission lines at 5876 angstrom and 6678 angstrom. The He I lines in these CTTSs contain both narrow emission cores, believed to come from near the accretion shock region on these stars, and broad emission components which may come from either a wind or the large-scale magnetospheric accretion flow. We detect strong polarization in the narrow component of the two He I emission lines in both stars. We observe a maximum implied field strength of 6.05 +/- 0.24 kG in the 5876 angstrom line of GQ Lup, making it the star with the highest field strength measured in this line for a CTTS. We find field strengths in the two He I lines that are consistent with each other, in contrast to what has been reported in the literature on at least one star. We do not detect any polarization in the broad component of the He I lines on these stars, strengthening the conclusion that they form over a substantially different volume relative to the formation region of the narrow component of the He I lines.

  • 41. Johns-Krull, C.M.
    et al.
    Valenti, J.A.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Saar, S.
    Hatzes, A.
    New Measurements of T Tauri Magnetic Fields: Testing Magnetospheric Accretion2001In: Magnetic Fields Across the Hertzsprung-Russell Diagram, ASP Conf. Ser., vol. 248, 2001, p. 527-Conference paper (Other scientific)
  • 42. Joshi, S.
    et al.
    Ryabchikova, T.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Sachkov, M.
    Tiwari, S. K.
    Chakradhari, N. K.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Time-resolved photometric and spectroscopic analysis of the luminous Ap star HD 1034982010In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 401, no 2, p. 1299-1307Article in journal (Refereed)
    Abstract [en]

    We present the results of the photometric and spectroscopic monitoring of the luminous Ap star HD 103498. The time-series photometric observations were carried out on 17 nights using a three-channel fast photometer attached to the 1.04-m optical telescope at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital. The photometric data from five nights in 2007 show a clear signature of 15-min periodicity. However, the follow-up observations during 2007-2009 did not reproduce any such periodicity. To confirm the photometric light variations, time-series spectroscopic observations were carried out with the 2.56-m Nordic Optical Telescope (NOT) at La Palma on 2009 February 2. No radial velocity variations were present in this data set, which is in full agreement with the photometric observations taken around the same date. Model atmosphere and abundance analysis of HD 103498 show that the star is evolved from the main sequence and its atmospheric abundances are similar to those of two other evolved Ap stars, HD 133792 and HD 204411: large overabundances of Si, Cr and Fe and moderate overabundances of the rare-earth elements. These chemical properties and a higher effective temperature distinguish HD 103498 from any known roAp star.

  • 43. Knoglinger, P.
    et al.
    Nesvacil, N.
    Kupka, F.
    Mittermayer, P.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Weiss, W.W.
    Bruntt, H.
    Tools and Methods for Abundance Analysis2003In: IAUS 210, Modelling of stellar atmospheres, 2003, p. E66-Conference paper (Other scientific)
  • 44.
    Kochukhov, O
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Piskunov, Nikolai
    Department of Physics and Astronomy, Observational Astronomy.
    Ilyin, I.
    Ilyina, S.
    Tuominen, I.
    Magnetic Doppler Imaging of alpha2 CVn2001In: Magnetic Fields Across the Hertzsprung-Russell Diagram, Conference Proceedings, 2001, p. 321-Conference paper (Other scientific)
  • 45.
    Kochukhov, Oleg
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Adelman, S.J.
    Gulliver, A.F.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Weather in stellar atmosphere revealed by the dynamics of mercury clouds in alpha Andromedae2007In: Nature Physics, ISSN 1745-2473, E-ISSN 1745-2481, Vol. 3, no 8, p. 526-529Article in journal (Refereed)
    Abstract [en]

    The formation of long-lasting structures at the surfaces of stars is commonly ascribed to the action of strong magnetic fields. This paradigm is supported by observations of evolving cool spots in the Sun and active late-type stars, and stationary chemical spots in the early-type magnetic stars. However, results of our seven-year monitoring of mercury spots in non-magnetic early-type star αAndromedae show that the picture of magnetically driven structure formation is fundamentally incomplete. Using an indirect stellar-surface mapping technique, we construct a series of two-dimensional images of starspots and discover a secular evolution of the mercury cloud cover in this star. This remarkable structure-formation process, observed for the first time in any star, is plausibly attributed to a non-equilibrium, dynamical evolution of the heavy-element clouds created by atomic diffusion, and may have the same underlying physics as the weather patterns on terrestrial and giant planets.

  • 46.
    Kochukhov, Oleg
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Bagnulo, S.
    Wade, G. A.
    Sangalli, L.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Landstreet, J. D.
    Petit, P.
    Sigut, T. A. A.
    Magnetic Doppler imaging of 53 Camelopardalis in all four Stokes parameters2004In: Astronomy & Astrophysics, ISSN 0004-6361, Vol. 414, p. 613-Article in journal (Refereed)
  • 47.
    Kochukhov, Oleg
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Drake, N.
    Piskunov, Nikolai
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    de la Reza, R.
    Multi-element abundance Doppler imaging of the rapidly oscillating Ap star HR 38312004In: Astronomy & Astrophysics, ISSN 0004-6361, Vol. 424, p. 935-Article in journal (Refereed)
  • 48.
    Kochukhov, Oleg
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Freytag, Bernd
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Steffen, M.
    3-D Hydrodynamic Simulation of Convection in A Stars2007In: IAUS 239, Convection in Astrophysics, 2007, Vol. 239, p. 68-70Conference paper (Other academic)
  • 49.
    Kochukhov, Oleg
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Heiter, Ulrike
    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.
    Ryde, N.
    Gustafsson, B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Bagnulo, S.
    Plez, B.
    Magnetic fields in M dwarf stars from high-resolution infrared spectra2009In: COOL STARS, STELLAR SYSTEMS AND THE SUN: Proceedings of the 15th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, 2009, Vol. 1094, p. 124-129Conference paper (Refereed)
    Abstract [en]

    Magnetic fields play a central role in the atmospheric properties and variability of active M dwarfs. Information on the strength and structure of magnetic fields in these objects is vital for understanding dynamo mechanisms and magnetically-driven activity of low-mass stars, and for constraining theories of star formation and evolution. We have initiated the first systematic high-resolution survey of magnetically sensitive infrared spectral lines in M dwarf stars using the CRIRES instrument at the ESO VLT. We have completed observations for a sample of 35 active and inactive M dwarfs. Here we report first results of our project, demonstrating a clear detection of magnetic splitting of lines in the spectra of several M dwarfs. We assess diagnostic potential of different Zeeman-sensitive lines in the observed spectral region and apply spectrum synthesis modelling to infer magnetic field properties of selected M dwarfs.

  • 50.
    Kochukhov, Oleg
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Makaganiuk, Vitalii
    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.
    Least-squares deconvolution of the stellar intensity and polarization spectra2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 524, no 1, p. A5-Article in journal (Refereed)
    Abstract [en]

    Context. Least-squares deconvolution (LSD) is a powerful method of extracting high-precision average line profiles from the stellar intensity and polarization spectra. This technique is widely used for detection, characterization, and detailed mapping of the temperature, magnetic, and chemical abundance structures on the surfaces of stars. Aims. Despite its common usage, the LSD method is poorly documented and has never been tested with realistic synthetic spectra. In this study we revisit the key assumptions of the LSD technique, clarify its numerical implementation, discuss possible improvements and give recommendations of how to make LSD results understandable and reproducible. We also address the problem of interpretation of the moments and shapes of the LSD profiles in terms of physical parameters. Methods. We have developed an improved, multiprofile version of LSD (iLSD) and have extended the deconvolution procedure to linear polarization analysis taking into account anomalous Zeeman splitting of spectral lines. The iLSD method is applied to the theoretical Stokes parameter spectra computed for a wide wavelength interval containing all relevant spectral lines. We test various methods of interpreting the mean profiles, investigating how coarse approximations of the multiline technique translate into errors of the derived parameters. Results. We find that, generally, the Stokes parameter LSD profiles do not behave as a real spectral line with respect to the variation of magnetic field and elemental abundance. This problem is especially prominent for the Stokes I (intensity) variation with abundance and Stokes Q (linear polarization) variation with magnetic field. At the same time, the Stokes V (circular polarization) LSD spectra closely resemble the profile of a properly chosen synthetic line for the magnetic field strength up to 1 kG. The longitudinal field estimated from the Stokes V LSD profile is accurate to within 10% for the field strength below 5 kG and to within a few percent for the fields weaker than 1 kG. Our iLSD technique offers clear advantages over the standard LSD method in the individual analysis of different chemical elements. Conclusions. We conclude that the usual method of interpreting the LSD profiles by assuming that they are equivalent to a real spectral line gives satisfactory results only in a limited parameter range and thus should be applied with caution. A more trustworthy approach is to abandon the single-line approximation of the average profiles and apply LSD consistently to observations and synthetic spectra.

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