The accretion disk and white dwarf during the quiescence of the dwarf novae VW Vulpeculae and chi leonis

Citation
Ck. Henry et Em. Sion, The accretion disk and white dwarf during the quiescence of the dwarf novae VW Vulpeculae and chi leonis, PUB AST S P, 113(786), 2001, pp. 970-973
Citations number
18
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC
ISSN journal
0004-6280 → ACNP
Volume
113
Issue
786
Year of publication
2001
Pages
970 - 973
Database
ISI
SICI code
0004-6280(200108)113:786<970:TADAWD>2.0.ZU;2-3
Abstract
We have carried out an International Ultraviolet Explorer archival comparat ive study of the two U Geminorum type dwarf novae VW Vulpeculae and chi Leo nis. The spectrum of chi Leo does not show any C IV, a feature normally see n in the vast majority of other dwarf novae. For VW Vul, a single-temperatu re high-gravity photosphere does not produce a consistent fit. The best-fit accretion disk model corresponds to M-wd =0.55 M-circle dot, i = 41 degree s, and (M)over dot =10(-9) M-circle dot yr(-1). For chi Leo, we find that a white dwarf model with T-eff =33,000 K gives the best fit to the far-UV sp ectrum. However, a model accretion disk with parameters M = 0.80 M-circle d ot, i = 60 degrees, and (M)over dot =10(-10) M-circle dot yr(-1) also gives a satisfactory fit to the far-UV continuum. However, the accretion rate de rived from VW Vul is within a factor of 3 of the critical value, while the accretion rate of chi Leo is within a factor of 60 of the critical rate. If we have identified the accreting white dwarf in chi Leo, then it strengthe ns the overall conclusion that the white dwarfs in cataclysmic variables ab ove the period gap appear to be a factor of 1.5-2 times hotter than the acc reting white dwarfs in dwarf novae below the period gap.