THE SPECTRUM OF EZ-CANIS-MAJORIS (HD 50896) TO THE LYMAN LIMIT WITH THE HOPKINS ULTRAVIOLET TELESCOPE

A unique flux-calibrated spectrum, extending to the Lyman limit of the Wolf-Rayet star EZ CMa (also known as WR 6, HD 50896, spectral type WN5) has been recorded by the Hopkins Ultraviolet Telescope. We compare the spectrum to a pure He continuum model with the stellar parameters L* = 10(5.2) L., R* = 4.5 R., T(eff) = 57,000 K, V(infinity) = 1700 km s-1, and M = 10(-4) yr-1. These parameters are very close to those derived by Hamann et al. (1988) from quantitative spectroscopy of ultraviolet, visual, and infrared He emission lines (although they represent only one solution from a locus of solutions that scale with distance). After correcting for interstellar atomic and molecular H absorption, assuming a reddening of E(B-V) = 0.06 +/- 0.03 and a distance of 2.1 kpc, we find the model is a fairly good representation of the visual and near-UV continuum flux, but it underestimates the flux at the Lyman limit by a factor of almost-equal-to 1.5. The lower limit in E(B-V) might account for this discrepancy. However, part of the discrepancy may also be due to blends of wind-broadened He II, N III-V, O VI, S III-IV and VI, P V, and Fe V-VI emission lines creating an elevated pseudocontinuum, an effect not accounted for in the pure He model. The precise balance of these two effects remains to be determined. We conclude that the model given above provides an adequate fit to the data.