Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Accreting White Dwarf in SS Cygni Revealed   We have carried out a combined Hubble Space Telescope (HST/GHRS) and Far
Ultraviolet Spectroscopic Explorer FUSE) analysis of the prototype dwarf nova
SS Cygni during quiescence. The FUSE and HST spectra were obtained at
comparable times after outburst and have matching flux levels where the two
spectra overlap. In our synthetic spectral analysis, we have used SS Cygni's
accurate HST FGS parallax giving d = 166pc, a newly determined mass for the
accreting white dwarf (Bitner et al. 2007) of Mwd=0.81Msun (lower than the
previous, widely used 1.2 Msun) and the reddening E_{B-V} values 0.04 (Verbunt
1987; La Dous 1991) and 0.07 (Bruch and Engel 1994) derived from the 2175A
absorption feature in the IUE LWP spectra. From the best-fit model solutions to
the combined HST + FUSE spectral energy distribution, we find that the white
dwarf is reaching a temperature Teff of 45-55,000K in quiescence, assuming
Log(g)= 8.3 with a solar composition accreted atmosphere. The exact temperature
of the WD depends on the reddening assumed and on the inclusion of a quiescent
low mass accretion rate accretion disk. Accretion disk models alone fit badly
in the FUSE range while, and if we take the distance to be a free parameter,
the only accretion disk model which fits well is for a discordant distance of
at least several hundred pc and an accretion rate (1.E-8 Msun/yr which is
unacceptably high for a dwarf nova in quiescence. We discuss the implications
of the white dwarf's temperature on the time-averaged accretion rate and long
term compressional heating models.

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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
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The categories of this paper are: acc-phys
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The categories of this paper are: math
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: chem-ph
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The categories of this paper are: cs
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: stat
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The categories of this paper are: eess
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ph