Bibcode
Hunter, I.; Dufton, P. L.; Smartt, S. J.; Ryans, R. S. I.; Evans, C. J.; Lennon, D. J.; Trundle, C.; Hubeny, I.; Lanz, T.
Bibliographical reference
Astronomy and Astrophysics, Volume 466, Issue 1, April IV 2007, pp.277-300
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4
2007
Journal
Citations
204
Refereed citations
175
Description
We present an analysis of high-resolution FLAMES spectra of
approximately 50 early B-type stars in three young clusters at different
metallicities, NGC 6611 in the Galaxy, N 11 in the Large Magellanic
Cloud (LMC) and NGC 346 in the Small Magellanic Cloud (SMC). Using the
tlusty non-LTE model atmospheres code, atmospheric parameters and
photospheric abundances (C, N, O, Mg and Si) of each star have been
determined. These results represent a significant improvement on the
number of Magellanic Cloud B-type stars with detailed and homogeneous
estimates of their atmospheric parameters and chemical compositions. The
relationships between effective temperature and spectral type are
discussed for all three metallicity regimes, with the effective
temperature for a given spectral type increasing as one moves to a lower
metallicity regime. Additionally the difficulties in estimating the
microturbulent velocity and the anomalous values obtained, particularly
in the lowest metallicity regime, are discussed. Our chemical
composition estimates are compared with previous studies, both stellar
and interstellar with, in general, encouraging agreement being found.
Abundances in the Magellanic Clouds relative to the Galaxy are discussed
and we also present our best estimates of the base-line chemical
composition of the LMC and SMC as derived from B-type stars.
Additionally we discuss the use of nitrogen as a probe of the
evolutionary history of stars, investigating the roles of rotational
mixing, mass-loss, blue loops and binarity on the observed nitrogen
abundances and making comparisons with stellar evolutionary models where
possible.
Based on observations at the European Southern Observatory in programmes
171.0237 and 073.0234. Tables 3-6 and Figs. 7-31 are only available in
electronic form at http://www.aanda.org