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Chemical abundances in 43 metal-poor stars

Published online by Cambridge University Press:  23 December 2005

Bengt Gustafsson ,
Martin Asplund ,
Bengt Edvardsson ,
Karin Jonsell ,
Pierre Magain  and
Poul Erik Nissen
Bengt Gustafsson
Affiliation:
Department of Astronomy and Space Physics, Box 515, SE751 20 Uppsala, Sweden email:[email protected], [email protected], [email protected]
Martin Asplund
Affiliation:
Mt Stromlo Observatory, Australian National University email: [email protected]
Bengt Edvardsson
Affiliation:
Department of Astronomy and Space Physics, Box 515, SE751 20 Uppsala, Sweden email:[email protected], [email protected], [email protected]
Karin Jonsell
Affiliation:
Department of Astronomy and Space Physics, Box 515, SE751 20 Uppsala, Sweden email:[email protected], [email protected], [email protected]
Pierre Magain
Affiliation:
Institute of Astrophysics and Geophysics, Université de Liège, Belgium email: [email protected]
Poul Erik Nissen
Affiliation:
Institute of Physics and Astronomy, Århus University, Denmark email: [email protected]
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Abstract

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We have derived abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe, Ni and Ba for 43 metal-poor field stars, mostly stars at the turn-off point and on the subgiant branch, in the interval ${-}3.0{<}$[Fe/H]${<}{-}0.4$. The analysis is differential relative to the Sun. Oxygen abundances, with consideration of NLTE effects, were derived from the OI 777.4 nm triplet lines. We find [O/Fe] to gradually increase with decreasing [Fe/H], though considerably slower than has earlier been obtained from OH lines in the UV. A scatter in [O,Mg,Ca,Ti/Fe] at a given [Fe/H] is found and we argue that this scatter is partly real. The deviations from the mean trends of abundance ratios vs [Fe/H] are found to correlate in non-trivial ways for different abundances. Similar trends are found from results of accurate studies by other groups. This seems to give further evidence for the hypothesis that the stars once formed in different subsystems, with different star-formation rates.

The paper is in press in A&A, may be obtained as astro-ph/0505118.

Keywords

Stars: abundancesGalaxy: haloGalaxy: evolution
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 1 , Symposium S228: From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution , May 2005 , pp. 259
Copyright
© 2005 International Astronomical Union