Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modeling the EUV spectra of optically thick boundary layers of dwarf
  novae in outburst   Here we compute detailed model spectra of recently published optically thick
one-dimensional radial baundary layer (BL) models in cataclysmic variables and
compare them with observed soft X-ray/extreme ultraviolet (EUV) spectra of
dwarf novae in outburst. Every considered BL model is divided into a number of
rings, and for each ring, a structure model along the vertical direction is
computed using the stellar-atmosphere method. The ring spectra are then
combined into a BL spectrum taking Doppler broadening and limb darkening into
account. Two sets of model BL spectra are computed, the first of them consists
of BL models with fixed white dwarf (WD) mass (1 M_sun) and various relative WD
angular velocities (0.2, 0.4, 0.6 and 0.8 break-up velocities), while the other
deals with a fixed relative angular velocity (0.8 break-up velocity) and
various WD masses (0.8, 1, and 1.2 M_sun). The model spectra show broad
absorption features because of blending of numerous absorption lines, and
emission-like features at spectral regions with only a few strong absorption
lines. The model spectra are very similar to observed soft X-ray/EUV spectra of
SS Cyg and U Gem in outburst. The observed SS Cyg spectrum could be fitted by
BL model spectra with WD masses 0.8 - 1 M_sun and relative angular velocities
0.6 - 0.8 break up velocities. These BL models also reproduce the observed
ratio of BL luminosity and disk luminosity. The difference between the observed
and the BL model spectra is similar to a hot optically thin plasma spectrum and
could be associated with the spectrum of outflowing plasma with a mass loss
rate compatible with the BL mass accretion rate. The suggested method of
computing BL spectra seems very promising and can be applied to other BL models
for comparison with EUV spectra of dwarf novae in outburst.

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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-th
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The categories of this paper are: patt-sol
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The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: math
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The categories of this paper are: hep-ex
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The categories of this paper are: math-ph
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The categories of this paper are: q-alg
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The categories of this paper are: physics
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The categories of this paper are: nucl-th