First Results from the Goddard High-Resolution Spectrograph: Spectroscopic Determination of Stellar Parameters of Melnick 42, an O3f Star in the Large Magellanic Cloud
Butler, K.; Kudritzki, R. P.; Puls, J.; Hutchings, J. B.; Heap, S. R.; Ebbets, D.; Hubeny, I.; Altner, B.; Voels, S. A.; Haser, S.; Pauldrach, A.
United States, Canada
Abstract
GHRS and optical (ESO 3.6 m) observations of the O3f star Melnick 42 in the 30 Doradus complex are reported. A first analysis reveals that with a luminosity of 2.3 x 10^6^ L_sun_ and a present mass of 100 M_sun_, Melnick 42 is one of the most luminous and massive stars known. An estimate of abundances indicates that iron and oxygen are very likely reduced by a factor of 4 relative to the Sun, whereas carbon is more strongly depleted and nitrogen is approximately solar. The terminal velocity of the stellar wind is 3000 km s^-1^. The mass-loss rate is 4 x 10^-6^ M_sun_ yr^-1^, with a large uncertainty. The excellent quality GHRS spectrum taken in a crowded region of the LMC demonstrates the superiority of the HST for quantitative ultraviolet spectroscopy of hot stars in other galaxies.