IUE SPECTROSCOPY OF THE NOVA-LIKE VARIABLE BZ CAM: CHARACTERISTICS OF ITS PECULIAR WIND OUTFLOW

Abstract

ABSTRACT We have analyzed 15 IUE low resolution SWP spectra of the peculiar hot nova-like object BZ Camelopardalis (= 0623+71), which is associated with a bow shock nebula. We determined approximate relative orbital phases of a series of spectra obtained continuously over a 28 hour time baseline by using the newly determined orbital period (P=0.1535 days) and ephemeris by Thorstensen et al. (1993). We find evidence of deepest absorption of the resonance doublet wind features C IV, Si IV, and N V near relative phase 0.2. In general, when the P Cygni resonance line absorption vanishes (strengthens), the Si IV emission strengthens (vanishes). We report dramatic temporal line profile variability of the C IV P Cygni feature and other strong wind absorptions at N V (1240), Si IV (1400), He II (1640) and N IV (1718), around the orbit, on timescales < 1 hour. The average terminal (blue edge) velocities (over 15 spectra) of the C IV and Si IV P Cygni features are -5300 and -5100 km s-1, respectively, while for higher temperature ion species (N V and He II), it is only -3900 and -3158 km s-1, respectively. Implications of the wind characteristics for the nature of its outflow, the origin of the bow-shaped nebula and the evolutionary status of BZ Cam are briefly discussed.