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Astron. Astrophys. 317, 82-89 (1997)


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Abundance analyses of a sample of five faint blue stars
in the galactic halo

T.R. Kendall 1, P.L. Dufton 1, F.P. Keenan 1, T.C. Beers 2 and N.C. Hambly 3

1 The Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast BT7 1NN, Ireland
2 Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
3 Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK

Received 7 March 1996 / Accepted 2 May 1996

Abstract

High resolution optical spectra of five faint high galactic latitude B-type stars, identified from a magnitude limited survey, have been analysed using LTE model atmosphere calculations. All targets have small projected rotational velocities ( [FORMULA] 30 km s [FORMULA] ) and hence may be evolved objects. This is supported by their chemical compositions, which indicate that they are old Population II stars; two stars also show enhanced nitrogen abundances probably due to the mixing of nuclear processed material to their surfaces. Their atmospheric parameters are consistent with a post-Asymptotic Giant Branch evolutionary status, although two targets may have evolved directly off the horizontal branch.

Key words: stars: early-type — stars: post-asymptotic giant branch — stars: abundances — Galaxy: halo

Send offprint requests to: P.L. Dufton


© European Southern Observatory (ESO) 1997

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