A Hubble Space Telescope STIS observation of VW Hydri at the exact far-ultraviolet onset of an outburst
UNSPECIFIED. (2004) A Hubble Space Telescope STIS observation of VW Hydri at the exact far-ultraviolet onset of an outburst. ASTROPHYSICAL JOURNAL, 614 (1 Part 2). L61-L64. ISSN 0004-637XFull text not available from this repository.
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 60degrees, and a white dwarf mass of 0.86 M-circle dot, 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.
|Item Type:||Journal Article|
|Subjects:||Q Science > QB Astronomy|
|Journal or Publication Title:||ASTROPHYSICAL JOURNAL|
|Publisher:||UNIV CHICAGO PRESS|
|Date:||10 October 2004|
|Number:||1 Part 2|
|Number of Pages:||4|
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