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Issue A&A
Volume 425, Number 1, October I 2004
Page(s) 187 - 206
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20040421



A&A 425, 187-206 (2004)
DOI: 10.1051/0004-6361:20040421

Subgiants as probes of galactic chemical evolution

P. Thorén, B. Edvardsson and B. Gustafsson

Department of Astronomy and Space Physics, Uppsala Astronomical Observatory, Box 515, 751 20 Uppsala, Sweden
    e-mail: bengt.edvardsson@astro.uu.se

(Received 10 March 2004 / Accepted 28 May 2004)

Abstract
Chemical abundances for 23 candidate subgiant stars have been derived with the aim at exploring their usefulness for studies of galactic chemical evolution. High-resolution spectra from ESO CAT-CES and NOT-SOFIN covered 16 different spectral regions in the visible part of the spectrum. Some 200 different atomic and molecular spectral lines have been used for abundance analysis of ~30 elemental species. The wings of strong, pressure-broadened metal lines were used for determination of stellar surface gravities, which have been compared with gravities derived from HIPPARCOS parallaxes and isochronic masses. Stellar space velocities have been derived from HIPPARCOS and Simbad data, and ages and masses were derived with recent isochrones. Only 12 of the stars turned out to be subgiants, i.e. on the "horizontal" part of the evolutionary track between the dwarf- and the giant stages. The abundances derived for the subgiants correspond closely to those of dwarf stars. With the possible exceptions of lithium and carbon we find that subgiant stars show no "chemical" traces of post-main-sequence evolution and that they are therefore very useful targets for studies of galactic chemical evolution.


Key words: stars: abundances -- stars: evolution

SIMBAD Objects



© ESO 2004


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