J/A+A/315/95 J/A+A/315/95 Chemical compositions of 3 LMC B stars. W R J Rolleston P J F Brown P L Dufton I D Howarth Astron. Astrophys. 315 95 1996 1996A&A...315...95R Abundances Stars, pre-main sequence galaxies: abundances Magellanic Clouds stars: abundances stars: individual (LH 104-24, PS 34-16, PS 34-144) High-resolution observations of three B-type main-sequence stars in the Large Magellanic Cloud (LMC) have been obtained with the UCL echelle spectrograph on the 3.9-m Anglo-Australian Telescope. These spectra and IUE low-resolution spectroscopic data have been analysed using LTE model-atmosphere techniques, to derive stellar atmospheric parameters and chemical compositions. As these stars lie on the hydrogen burning main-sequence, their surface abundances should reflect those of the present-day interstellar medium. From a differential analysis of LH 104-24 and PS 34-16 performed relative to the Galactic B-type stars {tau} Sco and {gamma} Peg, we conclude that there exists a general heavy-element underabundance of ~0.3dex within the LMC, but there is some evidence to suggest that these stars possess different oxygen and silicon abundances. The third star, PS 34-144, exhibits chemical anomalies, with a helium underabundance of 0.5dex and a mean metal deficiency of approximately 0.8dex. We classify this object as a Helium-weak star that is a member of the LMC. However, as additional processes such as diffusion may have occurred in its atmosphere, we do not believe that element abundances derived for PS 34-144 to be representative of the progenitor interstellar material.

LMC05 23.6 -69 45 LH 104 (LMC) (Stellar association)05 40.1 -69 25 PS 34-16 (LMC)05 04.6 -66 25 PS 34-144 (LMC)05 17.1 -66 02 Gamma Peg00 13.2 +15 11 Tau Sco16 35.9 -28 13

Line Rest wavelength of absorption feature 0.1nm Species Species --- l_PS34-16 Limit flag on PS34-16 --- PS34-16 Equivalent widths for PS 34-16 0.1pm q_PS34-16 Quality flag on PS34-16 number=1 A measure of the reliability of each measurement has been estimated with: a: having a typical accuracy of 10%; b: typical accuracy of 20% and c: accuracy probably worse than 20%. A superscript P denotes that the equivalent-width estimates of Peters (1976ApJS...30..551P) have been adopted. --- l_PS34-144 Limit flag on PS34-144 --- PS34-144 Equivalent widths for PS 34-144 0.1pm q_PS34-144 Quality flag on PS34-144 number=1 A measure of the reliability of each measurement has been estimated with: a: having a typical accuracy of 10%; b: typical accuracy of 20% and c: accuracy probably worse than 20%. A superscript P denotes that the equivalent-width estimates of Peters (1976ApJS...30..551P) have been adopted. --- l_LH104-24 Limit flag on LH104-24 --- LH104-24 Equivalent widths for LH 104-24 0.1pm q_LH104-24 Quality flag on LH104-24 number=1 A measure of the reliability of each measurement has been estimated with: a: having a typical accuracy of 10%; b: typical accuracy of 20% and c: accuracy probably worse than 20%. A superscript P denotes that the equivalent-width estimates of Peters (1976ApJS...30..551P) have been adopted. --- GamPeg Equivalent widths for gamma Peg 0.1pm q_GamPeg Quality flag on GamPeg number=1 A measure of the reliability of each measurement has been estimated with: a: having a typical accuracy of 10%; b: typical accuracy of 20% and c: accuracy probably worse than 20%. A superscript P denotes that the equivalent-width estimates of Peters (1976ApJS...30..551P) have been adopted. --- TauSco Equivalent widths for tau Sco 0.1pm q_TauSco Quality flag on TauSco number=1 A measure of the reliability of each measurement has been estimated with: a: having a typical accuracy of 10%; b: typical accuracy of 20% and c: accuracy probably worse than 20%. A superscript P denotes that the equivalent-width estimates of Peters (1976ApJS...30..551P) have been adopted. --- Patricia Bauer CDS 1996May03Robert Rolleston <R.Rolleston@Queens-Belfast.AC.UK> J_A+A_315_95.xml