EDP Sciences
Free Access
Volume 396, Number 1, December II 2002
Page(s) 53 - 64
Section Extragalactic astronomy
DOI https://doi.org/10.1051/0004-6361:20021088
Published online 22 November 2002

A&A 396, 53-64 (2002)
DOI: 10.1051/0004-6361:20021088

The present-day chemical composition of the LMC

W. R. J. Rolleston, C. Trundle and P. L. Dufton

Department of Pure & Applied Physics, The Queen's University of Belfast, BT7 1NN, Northern Ireland, UK
(Received 5 June 2002 / Accepted 24 July 2002)

High-resolution observations of five OB-type main-sequence stars in the Large Magellanic Cloud (LMC) have been obtained with the UCL échelle spectrograph on the 3.9-m Anglo-Australian Telescope. These spectra have been analysed using LTE model-atmosphere techniques, to derive stellar atmospheric parameters and chemical compositions. As these stars are located within the hydrogen burning main-sequence band, their surface abundances should reflect those of the present-day interstellar medium. Detailed line-by-line differential analyses have been undertaken relative to Galactic comparison stars. We conclude that there exists a general metal deficiency of $-0.31\pm0.04$ dex within the LMC, and find no significant abundance variations between cluster and field stars. There is also tentative evidence to suggest a lower oxygen to iron abundance ratio, and an over-deficiency of magnesium relative to the other $\alpha$-elements. These are discussed in terms of previous abundance analyses and models of discontinuous (or bursting) star formation within the LMC. Finally, there is some evidence to suggest a greater chemical enrichment of material within the $\ion{H}{ii}$ region LH 104.

Key words: stars: abundances -- stars: atmospheres -- stars: early-type -- galaxies:individual: Large Magellanic Cloud

Offprint request: W. R. J. Rolleston, R.Rolleston@qub.ac.uk

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