Reddened and Main Sequence Spectra

Two additional O3 giants in the LMC are shown in Figure 2. The far-UV spectrum of Sk137, located just north of 30 Doradus, is dominated by strong absorption blends of interstellar H, which have been identified from the work of [McCandliss et al. 1993]. Although its reddening of is moderate by Galactic standards, it is the largest in the present sample (Table 1). The UV flux of this star is also heavily depressed. Nevertheless, strong wind features of O VI and S VI can be discerned. Sk172 has a composite spectrum with a later OB type ([Walborn et al. 1995b]), and its reddening is also relatively high, . The H features are also present in its spectrum, albeit more weakly. Even weaker H absorptions may be present in the NGC 346/SMC spectra. Further analysis of these data, with HDE 269810 = Sk211 (Figure 1) as a relatively unreddened comparison, will yield valuable information about far-UV extinction and molecular hydrogen in the Magellanic Clouds.

The extreme deficiency of the stellar-wind profiles in SMC early-O dwarf spectra, including NGC 346 Nos. 4 and 6, was shown by [Walborn et al. 1995b]. This trend continues at the shorter wavelengths, as seen in their HUT data in Figure 2. Modeling of these spectra will provide significant information about massive stellar winds at low metallicity.