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The Chemical Compositions of the Extreme Halo Stars HE 0107-5240 and HE 1327-2326 Inferred from Three-dimensional Hydrodynamical Model Atmospheres
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.
2006 (English)In: Astrophysical Journal, ISSN 0004-637X, Vol. 664, no 2, L121-L124 p.Article in journal (Other (popular scientific, debate etc.)) Published
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.

Place, publisher, year, edition, pages
2006. Vol. 664, no 2, L121-L124 p.
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:uu:diva-18434OAI: oai:DiVA.org:uu-18434DiVA: diva2:46206
Available from: 2006-12-21 Created: 2006-12-21 Last updated: 2011-01-11

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