Submitted to Astronomical Journal The Chemical Composition of Two Supergiants in the Dwarf Irregular Galaxy WLM Kim A. Venn Macalester College, Saint Paul, MN, 55105;
[email protected] University of Minnesota, 116 Church Street S.E., Minneapolis, MN, 55455 Eline Tolstoy Kapteyn Institute, University of Groningen, PO Box 800, 9700AV Groningen, the Netherlands;
[email protected] Andreas Kaufer European Southern Observatory, Alonso de Cordova 3107, Santiago 19, Chile;
[email protected] Evan D. Skillman Department of Astronomy, University of Minnesota, 116 Church Street S.E., Minneapolis, MN, 55455;
[email protected] Sonya M. Clarkson Macalester College, Saint Paul, MN, 55105 arXiv:astro-ph/0306160v1 9 Jun 2003 Stephen J. Smartt Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK;
[email protected] Danny J. Lennon Isaac Newton Group of Telescopes (ING), Santa Cruz de La Palma, Canary Islands, E-38700, Spain;
[email protected] and Rolf P. Kudritzki –2– Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, 95822;
[email protected] ABSTRACT The chemical composition of two stars in WLM have been determined from high quality UVES data obtained at the VLT UT21. The model atmospheres analysis shows that they have the same metallicity, [Fe/H] = −0.38 ±0.20 (±0.29)2. Reliable magnesium abundances are determined from several lines of two ionization states in both stars resulting in [Mg/Fe] = −0.24 ±0.16 (±0.28). This result suggests that the [α(Mg)/Fe] ratio in WLM may be suppressed rel- ative to solar abundances (also supported by differential abundances relative to similar stars in NGC 6822 and the SMC).