High-Speed Optical Spectroscopy of a Cataclysmic Variable Wind: BZ Camelopardalis

BZ Cam is the first cataclysmic variable star with an accretion disk windevident in its optical spectrum. The wind was found by Thorstensen, whodiscovered intermittent P Cygni profiles occurring simultaneously in He I 5876Angstroms and H alpha. We have since obtained spectra with 0.4-Angstroms/pixeldispersion and 60-s time resolution. We find a wind much faster and more rapidly variable than the radiativelyaccelerated winds of OB stars, Wolf-Rayet stars, or luminous blue variables.Instead of showing blob ejection, the whole wind of BZ Cam appears to turn onand off. We use this to measure the acceleration law of a CV wind for the firsttime. The velocity increases linearly with time, attaining blue edge velocitiesnear -3000 km/s, and absorption velocities near -1700 km/s, in 6 to 8 min afterstarting near rest. We also find a subsequent linear deceleration to nearlyrest in 30 to 40 min, perhaps an effect of dilution as the wind expands. Noperiodicity from rotational outflow is obvious. This wind is erratic and incessantly variable, and perhaps bipolar andface-on, but not highly collimated. The P Cygni absorption events trace outsawtooth waves, occurring within 30 to 40 white dwarf radii from the disk. Thisis the approximate size of the disk, as well as the disk/wind transition regionrecently postulated by Knigge and Drew. We estimate a distance of 830 +/- 160pc, and an orbital inclination i such that 12 < i(degrees) < 40.Comment: 23 pages, LaTeX including 2 tables and 8 Encapsulated PostScript figures, requires AAS style files; AJ, accepte