A Reconnaissance of the 900--1200 Angstrom Spectra of Early O Stars in the Magellanic Clouds

The first survey of the far-UV (900--1200 A) spectra of O stars in the Magellanic Clouds, observed with the Hopkins Ultraviolet Telescope during the Astro-2 mission, is presented. Five objects in each Cloud were obtained, including four of type O3 (one of which is the current candidate for the most massive star known) and a pair of O4 If supergiants with remarkably different relative CNO strengths. All of the SMC objects are in its largest H II region, NGC 346, and show strong effects of the systemic metal deficiency. The systematic spectral-type dependence of the numerous stellar-wind features in this relatively little-studied wavelength range, including those of O VI and S VI, is illustrated and described. One of the LMC O3 stars, with EB-V = 0.25, displays strong interstellar H2 features.