2004ApJ...614L..61S -
Astrophys. J., 614, L61-L64 (2004/October-2)
A Hubble space telescope STIS observation of VW Hydri at the exact far-ultraviolet onset of an outburst.
SION E.M., CHENG F.H., GANSICKE B.T. and SZKODY P.
Abstract (from CDS):
We present an analysis of Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph data of VW Hyi that we acquired 14 days after a superoutburst. At the time of our observation, the system appears to be going into outburst with the longest wavelengths increasing in flux by a factor of 5 while the shortest wavelengths increase by only a factor of 2. Using the distance of 65 pc, a system inclination angle of 60°, and a white dwarf mass of 0.86 M☉, we carried out model fits involving a white dwarf by itself; an optically thick accretion disk by itself; a composite model using an optically thick accretion disk and a white dwarf; a two-temperature white dwarf model with a cooler, more slowly rotating photosphere and a hotter, rapidly rotating accretion belt; and a composite model involving a white dwarf and a rapidly rotating cooler disk ring heated up to a ``low'' temperature of 13-14,000 K. This component of temperature stays fairly constant throughout the HST observations, while the area of the disk ring increases by a factor of 12. We see evidence of a delay in the UV emission consistent with the outburst beginning outside of a disk truncation radius.
Abstract Copyright:
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Journal keyword(s):
Accretion, Accretion Disks - Stars: Dwarf Novae - Stars: Individual: Constellation Name: VW Hydri - Stars: White Dwarfs
Simbad objects:
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