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Issue A&A Volume 506, Number 1, October IV 2009 The CoRoT space mission: early results Page(s) 213 - 233 Section Stellar atmospheres DOI 10.1051/0004-6361/200911931 Published online 02 July 2009

A&A 506, 213-233 (2009)
DOI: 10.1051/0004-6361/200911931

Abundance analysis of prime B-type targets for asteroseismology

II. B6–B9.5 stars in the field of view of the CoRoT satellite

E. Niemczura^{1, 2}, T. Morel^{2, 3}, and C. Aerts<sup>2, 4

1</sup>  Astronomical Institute, Wrocław University, Kopernika 11, 51-622 Wrocław, Poland
    e-mail: eniem@astro.uni.wroc.pl
²  Institute of Astronomy, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
    e-mail: conny@ster.kuleuven.be
³  Institut d'Astrophysique et de Géophysique, Université de Liège, Allée du 6 août, Bât. B5c, 4000 Liège, Belgium
    e-mail: morel@astro.ulg.ac.be
⁴  Department of Astrophysics, IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL, Nijmegen, The Netherlands

Received 23 February 2009 / Accepted 24 May 2009

Abstract
Context.
Aims. The main goal of the ground-based seismology support program for the CoRoT mission was to obtain photometric and spectroscopic data for stars in the fields monitored by the satellite. These ground-based observations were collected in the GAUDI archive. High-resolution spectra of more than 200 B-type stars are available in this database, and about 45% of them is analysed here.
Methods. To derive the effective temperature of the stars, we used photometric indices. Surface gravities were obtained by comparing observed and theoretical Balmer line profiles. To determine the chemical abundances and rotational velocities, we used a spectrum synthesis method, which consisted of comparing the observed spectrum with theoretical ones based on the assumption of LTE.
Results. Atmospheric parameters, chemical abundances, and rotational velocities were determined for 89 late-B stars. The dominant species in their spectra are iron-peak elements. The average Fe abundance is 7.24  0.45 dex. The average rotational velocity is 126 km s^-1, but there are 13 and 20 stars with low and moderate  values, respectively. The analysis of this sample of 89 late B-type stars reveals many chemically peculiar (CP) stars. Some of them were previously known, but at least 9 new CP candidates, among which at least two HgMn stars, are identified in our study. These CP stars as a group exhibit  values lower than the stars with normal surface chemical composition.

Key words: stars: abundances -- stars: atmospheres -- stars: chemically peculiar

© ESO 2009

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