J/A+A/315/95 Chemical compositions of 3 LMC B stars. (Rolleston+ 1996)
The chemical compositions of three main-sequence B-type stars in the
Large Magellanic Cloud
Rolleston W.R.J., Brown P.J.F., Dufton P.L., Howarth I.D
<Astron. Astrophys. 315, 95 (1996)>
=1996A&A...315...95R 1996A&A...315...95R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Abundances
Keywords: galaxies: Magellanic Clouds - stars: abundances -
galaxies: abundances -
stars: individual: LH 104-24 (LMC), PS 34-16 (LMC), PS 34-144 (LMC)
Description:
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 τ Sco and γ 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.
Objects:
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RA (2000) DE Designation(s)
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05 23.6 -69 45 LMC
05 40.1 -69 25 LH 104 (LMC) (Stellar association)
05 04.6 -66 25 PS 34-16 (LMC)
05 17.1 -66 02 PS 34-144 (LMC)
00 13.2 +15 11 Gamma Peg
16 35.9 -28 13 Tau Sco
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2 66 103 Chemical composition
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Byte-by-byte Description of file: table2
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Bytes Format Units Label Explanations
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1- 7 F7.2 0.1nm Line Rest wavelength of absorption feature
9- 14 A6 --- Species Species
17 A1 --- l_PS34-16 Limit flag on PS34-16
18- 21 I4 0.1pm PS34-16 ? Equivalent widths for PS 34-16
22 A1 --- q_PS34-16 [abc] Quality flag on PS34-16 (1)
27 A1 --- l_PS34-144 Limit flag on PS34-144
28- 31 I4 0.1pm PS34-144 ? Equivalent widths for PS 34-144
32 A1 --- q_PS34-144 [abc] Quality flag on PS34-144 (1)
39 A1 --- l_LH104-24 Limit flag on LH104-24
40- 42 I3 0.1pm LH104-24 ? Equivalent widths for LH 104-24
43 A1 --- q_LH104-24 [abc] Quality flag on LH104-24 (1)
51- 53 I3 0.1pm GamPeg ? Equivalent widths for gamma Peg
54 A1 --- q_GamPeg [abc] Quality flag on GamPeg (1)
62- 64 I3 0.1pm TauSco ? Equivalent widths for tau Sco
65 A1 --- q_TauSco [abc] Quality flag on TauSco (1)
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Note (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 1976ApJS...30..551P) have been adopted.
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Acknowledgements: Robert Rolleston
(End) Patricia Bauer [CDS] 03-May-1996