ORFEUS-SPAS II EUV Spectroscopy of ǫ CMa (B2 II) 1

We report on EUV spectroscopic observations of the B bright giant ǫ CMa made during the ORFEUS-SPAS II mission. We assess the performance of the instrument in the EUV and find that the effective area is roughly three times that of the EUVE long wavelength spectrometer and that the spectral resolution is λ/∆λ ≈ 1250. We identify most of the features, qualitatively compare different models, and examine the wind-broadened O V and Si IV lines, which display blue edge velocities up to 800 km s. Subject headings: line: identification — stars: atmospheres — stars: early-type — stars: individual (ǫ CMa) — ultraviolet: stars Based on the development and utilization of ORFEUS (Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometers), a collaboration of the Institute for Astronomy and Astrophysics at the University of Tübingen, the Space Astrophysics Group of the University of California at Berkeley, and the Landessternwarte Heidelberg.