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  • 1. Allende Prieto, C.
    et al.
    Asplund, M.J.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Garcia Lopez, R.J.
    Lambert, D.L.
    Nordlund, Å.
    R200,000 Spectroscopic Observations of Procyon. The surface Convection and Radial Velocity2001In: ASPCArticle in journal (Refereed)
  • 2. Aoki, W
    et al.
    Frebel, A
    Christlieb, Norbert
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Norris, J
    Beers, T
    Minezaki, T
    Barklem, Paul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Honda, S
    Takada-Hidai, M
    Asplund, M
    Ryan, S
    Tsangarides, S
    Eriksson, Kjell
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    An abundance study of the most iron-poor star HE1327-2326 with Subaru/HDS2006In: International Symposium on Origin of Matter and Evolution of Galaxies, 2006Conference paper (Other scientific)
  • 3. Aoki, W
    et al.
    Frebel, A
    Christlieb, Norbert
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Norris, J
    Beers, T
    Minezaki, T
    Barklem, Paul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Honda, S
    Takada-Hidai, M
    Asplund, M
    Ryan, S
    Tsangarides, S
    Eriksson, Kjell
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    HE 1327-2326, an Unevolved Star with [Fe/H] < -5.0.: I. A Comprehensive Abundance Analysis2006In: The Astrophysical Journal, Vol. 639, p. 897-917Article in journal (Refereed)
  • 4.
    Asplund, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Effects of Convection on Line Profiles and Abundances2001In: ASPCArticle in journal (Other (popular scientific, debate etc.))
  • 5.
    Asplund, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    O/Fe in metal-poor main sequence and subgiant stars2002In: A&A, Vol. 07Article in journal (Refereed)
  • 6.
    Asplund, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Signatures of Convection in teh Spectrum of Procyon: Fundamental Parametrs and Iron Abundance2002In: ApJ, Vol. 03Article in journal (Refereed)
  • 7.
    Asplund, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Sulphur abundances in disk stars: Acorrelation with silicon2002In: A&A, Vol. 07Article in journal (Refereed)
  • 8.
    Asplund, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    The Star Too Tough to Die2001In: S&T, Vol. 11Article in journal (Refereed)
  • 9.
    Asplund, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    V838 Monocerotis-a Newly Discovered, Very Peculiar, Slow Nova-Like Objekt2002In: ASPCArticle in journal (Refereed)
  • 10.
    Asplund, Martin
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Faculty of Science and Technology, Astronomical observatory. Department of Physics and Astronomy, Theoretical Astrophysics.
    Collet, Remo
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Faculty of Science and Technology, Astronomical observatory. Department of Physics and Astronomy, Theoretical Astrophysics.
    Radiative Transfer in 3D Model Stellar Atmospheres2003In: ASP Conference Proceedings: 3D Stellar Evolution, 2003, p. 197-Conference paper (Other (popular scientific, debate etc.))
    Abstract [en]

    Recently 3D hydrodynamical simulations of stellar surface convection have become feasible thanks to advances in computer technology and efficient numerical algorithms. Available observational diagnostics indicate that these models are highly realistic in describing the topology of stellar granulation and for spectral line formation purposes. The traditional free parameters (mixing length parameters, micro- and macroturbulence) always inherent in standard 1D analyses have thus finally become obsolete. These 3D models can therefore both shed light on the elusive nature of stellar convection as well as be employed in element abundance analyses. In the present contribution we will describe some aspects of the models and possible applications of them in terms of radiative transfer.

  • 11.
    Asplund, Martin
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Lambert, D,L.
    Nissen, P.E.
    Primas, F.
    Smith, V.V.
    Lithium isotope ratios in metal-poor halo stars2001Conference paper (Other (popular scientific, debate etc.))
  • 12.
    Barklem, Paul
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Christlieb, Norbert
    Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Beers, T.C.
    Hill, V.
    Bessell, M.S.
    Holmberg, J.
    Marsteller, B.
    Rossi, S.
    Zickgraf, F.-J.
    Reimers, D.
    The Hamburg/ESO R-process Enhanced Star survey (HERES).: II. Spectroscopic analysis of the survey sample2005In: Astronomy and Astrophysics, Vol. 439, p. 129-151Article in journal (Refereed)
  • 13.
    Barklem, Paul
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Christlieb, Norbert
    Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Beers, T.C.
    Hill, V
    Holmberg, J
    Marsteller, B
    Rossi, S
    Zickgraf, F.-J
    Bessell, M.S.
    The Hamburg/ESO R-process Enhanced Star survey (HERES).: Abundances2005In: From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution, IAU Symposium Proceedings of the international Astronomical Union 228, 2005, p. 439-443Conference paper (Other (popular scientific, debate etc.))
  • 14. Beers, T.C.
    et al.
    Barklem, Paul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Christlieb, Norbert
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Hill, V.
    Efficient Searches for r-Process-Enhanced, Metal-Poor Stars2005In: Nuclear Physics A, Vol. 758, p. 595-598Article in journal (Other scientific)
  • 15. Beers, T.C.
    et al.
    Barklem, P.S.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Christlieb, Norbert
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Hill, V.
    Efficient searches for r-process-enhanced, metal-poor stars2005In: Nuclei in the Cosmos VIII, 2005Conference paper (Other scientific)
  • 16. Bensby, Thomas
    et al.
    Oey, Sally
    Feltzing, Sofia
    Gustafsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Disentangling the Hercules Stream2007In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 655, no 2, p. L89-L92Article in journal (Refereed)
    Abstract [en]

    Using high-resolution spectra of nearby F and G dwarf stars, we have investigated the detailed abundance and age structure of the Hercules stream. We find that the stars in the stream have a wide range of stellar ages, metallicities, and element abundances. By comparing to existing samples of stars in the solar neighborhood with kinematics typical of the Galactic thin and thick disks, we find that the properties of the Hercules stream distinctly separate into the abundance and age trends of the two disks. Hence, we find it unlikely that the Hercules stream is a unique Galactic stellar population but rather is a mixture of thin and thick disk stars. This points toward a dynamical origin for the Hercules stream, probably caused by the Galactic bar.

  • 17. Bessell, M.S.
    et al.
    Christlieb, Norbert
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Gustafsson, B.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    On the oxygen abundance of HE0107-52402004In: Astrophysical Journal: Letters, Vol. 612, no 1, p. 61-63Article in journal (Refereed)
  • 18.
    Bladh, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Susanne, Höfner
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Aringer, Bernhard
    Eriksson, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Exploring wind-driving dust species in cool luminous giants III: Wind models for M-type AGB stars2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 575, article id A105Article in journal (Refereed)
  • 19. Bobrowsky, Peter
    et al.
    Rickman, HansUppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics. Astronomiska Observatoriet.
    Comet/Asteroid Impacts and Human Society2007Collection (editor) (Other scientific)
  • 20. Byström, J.
    et al.
    Ryde, Nils
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics. Astronomiska observatoriet.
    Feltzing, S.
    holmberg, J.
    Bensby, T.
    The Determination of Stellar Parameters of Giants in the Galactic Disks and Bulge2007In: The Determination of Stellar Parameters of Giants in the Galactic Disks and Bulge: Proceedings of IAU Symposium 241, 2007, p. 235-236Conference paper (Other scientific)
    Abstract [en]

    Here, we present our on-going work on the determination of stellar parameters of giants in the Galactic Disks and Bulge observed with UVES on the VLT. We present some preliminarily results.

  • 21. Christlieb, N.
    et al.
    Beers, T.C.
    Barklem, Paul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Bessell, M.S.
    Hill, V.
    Holmberg, J.
    Korn, A.J.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Marsteller, B.J.
    Mashonkina, L.
    Qian, Y.-Z.
    Rossi, S.
    Wasserburg, G.J.
    et al,
    The Hamburg/ESO R-process Enhanced Star survey (HERES).: I. Project description, and discovery of two stars with strong enhancements of neutron-capture elements2004In: Astronomy and Astrophysics, Vol. 428, p. 1027-1037Article in journal (Refereed)
  • 22. Christlieb, N.
    et al.
    Bessell, M. S.
    Beers, T. C.
    Gustafsson, B
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Korn, A.
    Barklem, Paul
    Department of Astronomy and Space Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Karlsson, T
    Mizuno-Wiedner, M.
    Rossi, S.
    A stellar relic from the early Milky Way2002In: Nature, Vol. 419, p. 904-906Article in journal (Refereed)
  • 23. Christlieb, N.
    et al.
    Gustafsson, B
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Korn, A.J.
    Barklem, Paul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Beers, T.C.
    Bessell, M.S.
    Karlsson, T.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Mizuno-Wiedner, M.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    HE0107, A Chemically Ancient Star.: I. A Detailed Abundance Analysis2004In: The Astrophysical Journal, Vol. 603, p. 708-728Article in journal (Refereed)
  • 24.
    Collet, Remo
    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, Astronomical observatory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Asplund, Martin
    Trampedach, Regner
    3D Hydrodynamical model stellar atmospheres of metal-poor red giants2005In: Proceedings of the International Astronomical Union, vol. 1: From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution, 2005, p. 247-248Conference paper (Other academic)
    Abstract [en]

    We investigate the main differences between static 1D and 3D time-dependent model stellar atmospheres of red giants at very low metallicities. We focus in particular on the impact of 3D LTE spectral line formation on the derivation of elemental abundances for the extremely metal-poor ([Fe/H] ≈-5.3) red giant HE 0107-5240.

  • 25.
    Collet, Remo
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Faculty of Science and Technology, Astronomical observatory. Department of Physics and Astronomy, Theoretical Astrophysics.
    Asplund, Martin
    Trampedach, Regner
    The Chemical Compositions of the Extreme Halo Stars HE 0107-5240 and HE 1327-2326 Inferred from Three-dimensional Hydrodynamical Model Atmospheres2006In: Astrophysical Journal, ISSN 0004-637X, Vol. 664, no 2, p. L121-L124Article in journal (Other (popular scientific, debate etc.))
    Abstract [en]

    We investigate the impact of realistic three-dimensional (3D) hydrodynamical model stellar atmospheres on the determination of elemental abundances in the carbon-rich, hyper-iron-poor stars HE 0107-5240 and HE 1327-2326. We derive the chemical compositions of the two stars by means of a detailed 3D analysis of spectral lines under the assumption of local thermodynamic equilibrium (LTE). The lower temperatures of the line-forming regions of the hydrodynamical models cause changes in the predicted spectral line strengths. In particular, we find the 3D abundances of C, N, and O to be lower by about -0.8 dex (or more) than estimated from a 1D analysis. The 3D abundances of iron peak elements are also decreased but by smaller factors (about -0.2 dex). We caution, however, that the neglected non-LTE effects might actually be substantial for these metals. We finally discuss possible implications for studies of early Galactic chemical evolution.

  • 26.
    Collet, Remo
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Faculty of Science and Technology, Astronomical observatory. Department of Physics and Astronomy, Theoretical Astrophysics.
    Garcia Perez, Ana E.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Faculty of Science and Technology, Astronomical observatory. Department of Physics and Astronomy, Theoretical Astrophysics.
    Asplund, M.
    Thevenin, F.
    Effects of UV Line Blanketing on the Non-LTE Fe I Line Formation2003In: International Astronomical Union Symposium: Modelling of Stellar Atmospheres, 2003, p. B3-Conference paper (Other (popular scientific, debate etc.))
  • 27. de Val-Borro, Miguel
    et al.
    Edgar, Richard
    Artymowicz, Pawel
    Ciecilag, P.
    Cresswell, P.
    D'Angelo, Genaro
    Delgado-Donate, Eduardo
    Dirksen, G.
    Fromang, Sebastien
    Gawryszczak, A.
    Klahr, Hubert
    Kley, Willy
    Lyra, Wladimir
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Masset, Frederic
    Mellema, Garrelt
    Nelson, Richard
    Paardekooper, Simje-Jan
    Peplinski, Adam
    Pierens, A.
    Plewa, T.
    Rice, Ken
    Schäfer, C.
    Speith, R.
    A comparative study of disk-planet interaction2006In: Monthly Notices of the Royal Astronomic Society, Vol. 370, no 529, p. 29-Article in journal (Refereed)
    Abstract [en]

    We perform numerical simulations of a disc–planet system using various grid-based and smoothed particle hydrodynamics (SPH) codes. The tests are run for a simple setup where Jupiter and Neptune mass planets on a circular orbit open a gap in a protoplanetary disc during a few hundred orbital periods. We compare the surface density contours, potential vorticity and smoothed radial profiles at several times. The disc mass and gravitational torque time evolution are analysed with high temporal resolution. There is overall consistency between the codes. The density profiles agree within about 5 per cent for the Eulerian simulations. The SPH results predict the correct shape of the gap although have less resolution in the low-density regions and weaker planetary wakes. The disc masses after 200 orbital periods agree within 10 per cent. The spread is larger in the tidal torques acting on the planet which agree within a factor of 2 at the end of the simulation. In the Neptune case, the dispersion in the torques is greater than for Jupiter, possibly owing to the contribution from the not completely cleared region close to the planet.

  • 28.
    Emma, Olsson
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Haensel, P.
    Pethick, C.J.
    Static response of fermi liquids with tensor interactions2004In: PhRvC, Vol. 8Article in journal (Refereed)
  • 29. Fouchard, Marc
    et al.
    Froeschlé, Christiane
    Breiter, Sławomir
    Ratajczak, Roman
    Valsecchi, Giovanni B.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Astronomiska Observatoriet. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Methods for the Study of the Dynamics of the Oort Cloud Comets: II. Modelling the Galactic Tide2007In: Topics in Gravitational Dynamics: Solar, Extra-Solar and Galactic Systems / [ed] Daniel Benest, Claude Froeschle and Elena Lega, Berlin, Heidelberg: Springer-Verlag , 2007, p. 273-296Chapter in book (Other academic)
  • 30. Fouchard, Marc
    et al.
    Froeschlé, Christiane
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Astronomiska Observatoriet. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Valsecchi, Giovanni B.
    Methods for the Study of the Dynamics of the Oort Cloud Comets: I: Modelling the Stellar Perturbations2007In: Topics in Gravitational Dynamics: Solar, Extra-Solar and Galactic Systems / [ed] Daniel Benest, Claude Froeschle and Elena Lega, Berlin, Heidelberg: Springer-Verlag , 2007, p. 257-272Chapter in book (Other academic)
  • 31. Frebel, A.
    et al.
    Aoki, W.
    Christlieb, N.
    Ando, H.
    Asplund, M.
    Barklem, Paul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Beers, T.C.
    Eriksson, Kjell
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Nucleosynthetic signatures of the first stars2005In: Nature, Vol. 434, p. 871-873Article in journal (Refereed)
  • 32. Frebel, A
    et al.
    Aoki, W
    Christlieb, N
    Ando, H
    Asplund, M
    Barklem, Paul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Beers, T.C.
    Eriksson, Kjell
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Fechner, C.
    Fujimoto, M.Y.
    The new record holder for the most iron-poor star: HE 1327 2326: A dwarf or subgiant with Fe/H = -5.42005In: From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution: IAU Symposium 228, 2005, p. p. 207-212Conference paper (Other scientific)
  • 33.
    Garcia-Perez, Ana Elia
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Asplund, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Kiselman, D.
    Departure from LTE in Be line formation2001Conference paper (Other (popular scientific, debate etc.))
  • 34.
    García Pérez, Ana Elia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    Asplund, Martin
    Primas, Francesca
    Nissen, Poul Erik
    Gustafsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Oxygen abundances in metal-poor subgiants as determined from [OI], OI and OH lines2006In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 451, no 2, p. 621-642Article in journal (Refereed)
    Abstract [en]

    The debate on the oxygen abundances of metal-poor stars has its origin in contradictory results obtained using different abundance indicators. To achieve a better understanding of the problem we have acquired high quality spectra with the Ultraviolet and Visual Echelle Spectrograph at VLT, with a signal-to-noise of the order of 100 in the near ultraviolet and 500 in the optical and near infrared wavelength range. Three different oxygen abundance indicators, OH ultraviolet lines around 310.0 nm, the [O I] line at 630.03 nm and the O I lines at 777.1-5 nm were observed in the spectra of 13 metal-poor subgiants with . Oxygen abundances were obtained from the analysis of these indicators which was carried out assuming local thermodynamic equilibrium and plane-parallel model atmospheres. Abundances derived from O I were corrected for departures from local thermodynamic equilibrium. Stellar parameters were computed using -vs.-color calibrations based on the infrared flux method and Balmer line profiles, Hipparcos parallaxes and lines. [O/Fe] values derived from the forbidden line at 630.03 nm are consistent with an oxygen/iron ratio that varies linearly with [Fe/H] as . Values based on the O I triplet are on average (s.d.) higher than the values based on the forbidden line while the agreement between OH ultraviolet lines and the forbidden line is much better with a mean difference of the order of (s.d.). In general, our results follow the same trend as previously published results with the exception of the ones based on OH ultraviolet lines. In that case our results lie below the values which gave rise to the oxygen abundance debate for metal-poor stars.

  • 35.
    Gustafsson, Bengt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Gaia and Metal-Poor Stars2006In: ASP Conference Series, Vol. 523, p. 387-399Article, review/survey (Other (popular scientific, debate etc.))
  • 36.
    Gustafsson, Bengt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Model Atmospheres and Stellar Abundance Analysis2004In: Carnegie Observatories Centennial Symposia: Origin and Evolution of the Elements, 2004Chapter in book (Refereed)
  • 37.
    Gustafsson, Bengt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Nucleosynthesis and future stellar abundance determinations2004In: EAS Publ. Ser., Vol. 11, p. 21-50Article, review/survey (Other (popular scientific, debate etc.))
  • 38.
    Gustafsson, Bengt
    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, Theoretical Astrophysics.
    Towards a satisfactory understanding of AGB-Star Atmospheres2007In: Why galaxies care about AGB stars: Their importance as actors and probes / [ed] Kerschbaum F; Charbonnel C; Wing RF, 2007, Vol. 378, p. 60-70Conference paper (Other academic)
    Abstract [en]

    The understanding and the modelling of the atmospheres of AGB stars are discussed and found to be unsatisfactory for most purposes. A number of developments and possible actions to improve this situation are considered.

  • 39.
    Gustafsson, Bengt
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Asplund, Martin
    Edvardsson, Bengt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Jonsell, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Magain, Pierre
    Nissen, Poul-Erik
    Chemical abundances in 43 metal-poor stars2005In: IAUS, 2005, p. 228, 259-Conference paper (Refereed)
  • 40.
    Gustafsson, Bengt
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Edvardsson, Bengt
    Department of Physics and Astronomy, Theoretical Astrophysics.
    Eriksson, Kjell
    Department of Physics and Astronomy, Theoretical Astrophysics.
    Gråe-Jørgensen, Uffe
    Mizuno-Wiedner, Michelle
    Department of Physics and Astronomy, Theoretical Astrophysics.
    Plez, Bertrand
    A new MARCS Grid2002In: International Astronomical Union Symposium: Modelling of Stellar Atmospheres, 2002, p. A2-Conference paper (Other scientific)
    Abstract [en]

    An extensive grid of spherically symmetric model atmospheres of stars with 1. 2500 K <= Teff <= 8000 K, 2. -1.0 <= log g (= log GM/R2) <= 5.0 (cgs units), 3. different combinations of M and R, 4. -5 <= [A/H] <= 1, and 5. a number of CNO abundance combinat

  • 41.
    Gustafsson, Bengt
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Wahlin, Rurik
    The Chemical Composition of Red Giants, AGB Stars and Planetary2006In: IAUS, Vol. 234, p. 8-Article, review/survey (Other (popular scientific, debate etc.))
  • 42.
    Gustafsson, Björn
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    The virtue of looking in another direction2003In: UppOR, p. 59-Article in journal (Other (popular scientific, debate etc.))
  • 43.
    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.
    Eriksson, Kjell
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Geometry of giant star model atmospheres: A consistency test2006In: Astronomy & Astrophysics, Vol. 452, p. 1039-Article in journal (Refereed)
  • 44.
    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)
  • 45.
    Henriksson, Göran
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    A New Chronology of the Old Babylonian Kingdom and Ur I-III Based on Identification of Solar and Lunar Eclipses2006In: Cosmic Catastrophies, 2006Conference paper (Refereed)
  • 46.
    Henriksson, Göran
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Some Problems in Minoan Archaeoastronomy2006In: Cosmic Catastrophies, 2006Conference paper (Other (popular scientific, debate etc.))
  • 47.
    Höfner, Susanne
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Headwind: Modelling Mass Loss of AGB Stars, Against All Odds2007In: Why Galaxies Care About AGB Stars: Their Importance as Actors and Probes, 2007, p. p.145-155Conference paper (Other scientific)
    Abstract [en]

    The intricate interplay of atmospheric shock waves and a complex, variable radiation field with non-equilibrium dust formation presents a considerable challenge to self-consistent modelling of atmospheres and winds of AGB stars. Nevertheless it is clear that realistic models predicting mass loss rates and synthetic spectra are crucial for our understanding of this important phase of stellar evolution. While a number of questions are still open, significant progress has been achieved in recent years. In particular, self-consistent models for atmospheres and winds of C-stars have reached a level of sophistication which allows direct quantitative comparison with observations. In the case of stars with C/O < 1, however, recent work points to serious problems with the dust-driven wind scenario. This contribution analyzes the basic ingredients of this scenario with analytical estimates, focusing on dust formation, non-grey effects, and differences between C-rich and O-rich environments, as well as discussing the status of detailed dynamical wind models and current trends in this field.

  • 48.
    Höfner, Susanne
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Solens lysande framtid2007In: Populär Astronomi, no 4, p. 16-18Article in journal (Other (popular scientific, debate etc.))
  • 49. J.G., Cohen
    et al.
    Norbert, Christlieb
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Faculty of Science and Technology, Astronomical observatory. Department of Physics and Astronomy, Theoretical Astrophysics.
    A., McWilliam
    S., Shectman
    I., Thompson
    G.J., Wasserburg
    I., Ivans
    M., Dehn
    T., Karlsson
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Faculty of Science and Technology, Astronomical observatory. Department of Physics and Astronomy, Theoretical Astrophysics.
    J, Melendez
    Abundances In Very Metal-Poor Dwarf Stars2004In: Astrophysical Journal, ISSN 0004-637X, Vol. 603, no 2, p. 1107-1135Article in journal (Other (popular scientific, debate etc.))
    Abstract [en]

    We discuss the detailed composition of 28 extremely metal-poor (EMP) dwarfs, 22 of which are from the Hamburg/ESO Survey (HES), based on Keck echelle spectra. Our sample has a median [Fe/H] of -2.7 dex, extends to -3.5 dex, and is somewhat less metal-poor than was expected from [Fe/H](HK, HES) determined from low-resolution spectra. Our analysis supports the existence of a sharp decline in the distribution of halo stars with metallicity below [Fe/H]=-3.0 dex. So far no additional turnoff stars with [Fe/H]<-3.5 have been identified in our follow-up efforts. For the best-observed elements between Mg and Ni, we find that the abundance ratios appear to have reached a plateau, i.e., [X/Fe] is approximately constant as a function of [Fe/H], except for Cr, Mn, and Co, which show trends of abundance ratios varying with [Fe/H]. These abundance ratios at low metallicity correspond approximately to the yield expected from Type II supernovae (SNe) with a narrow range in mass and explosion parameters; high-mass Type II SN progenitors are required. The dispersion of [X/Fe] about this plateau level is surprisingly small and is still dominated by measurement errors rather than intrinsic scatter. These results place strong constraints on the characteristics of the contributing SNe. The dispersion in neutron-capture elements and the abundance trends for Cr, Mn, and Co are consistent with previous studies of evolved EMP stars. We find halo-like enhancements for the α-elements Mg, Ca, and Ti, but solar Si/Fe ratios for these dwarfs. This contrasts with studies of EMP giant stars, which show Si enhancements similar to other α-elements. Sc/Fe is another case where the results from EMP dwarfs and from EMP giants disagree; our Sc/Fe ratios are enhanced compared to the solar value by ~0.2 dex. Although this conflicts with the solar Sc/Fe values seen in EMP giants, we note that α-like Sc/Fe ratios have been claimed for dwarfs at higher metallicity. Two dwarfs in the sample are carbon stars, while two others have significant C enhancements, all with 12C/13C ~7 and with C/N between 10 and 150. Three of these C-rich stars have large enhancements of the heavy neutron capture elements, including lead, which implies a strong s-process contribution, presumably from binary mass transfer; the fourth shows no excess of Sr or Ba.

  • 50.
    Jonsell, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Faculty of Science and Technology, Astronomical observatory. Department of Physics and Astronomy, Theoretical Astrophysics.
    A Study of the Chemical Composition of Halo Stars2004In: Origin and Evolution of the Elements, 2004Conference paper (Other (popular scientific, debate etc.))
12 1 - 50 of 99
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