2003ApJ...582..352W -
Astrophys. J., 582, 352-357 (2003/January-1)
Composite accretion disk and white dwarf model analyses of the quiescence of dwarf novae: EM Cygni, CZ Orionis, and WW Ceti.
WINTER L. and SION E.M.
Abstract (from CDS):
We explore the origin of the far-UV (FUV) spectra of three dwarf novae using combined high-gravity photosphere and accretion disk models. We have carried out an IUE archival comparative study of the three U Gem-type dwarf novae EM Cyg, CZ Ori, and WW Cet. For EM Cyg, the FUV spectrum during quiescence is dominated by an accretion disk with M{dot}=5x10–11 M☉.yr–1 contributing 92% of the FUV light and a white dwarf with upper limit Teff<24,000 K contributing ≲8% of the light. For CZ Ori, the accretion disk with M{dot}=3.5x10–10 M☉.yr–1 contributes 99% of the FUV light while the white dwarf has an upper limit Teff<21,000 K and contributes ≲1% of the light. For WW Cet, we find that best-fitting disk models and disk plus white dwarf models yield a distance that appears far too large. A single-temperature white dwarf fit with Teff=22,000 K implies a distance of 150 pc. CZ Ori and EM Cyg are dominated by the accretion disk during quiescence but with accretion rates that differ by over a factor of 10. In the case of EM Cyg, which has a higher inclination, it is possible that the nearly edge-on aspect of the disk may hide a much hotter white dwarf. There are now 17 analyzed dwarf nova systems with Porb<120 mintues and 11 systems with Porb>180 m. The average Teff below the lower boundary of the period gap is Teff=15,547 K, while the average Teffabove the upper boundary of the period gap is Teff=31,182 K. The Teff of the white dwarfs strengthens the overall conclusion that the white dwarfs in cataclysmic variables above the period gap appear to be a factor of 2 times hotter than the accreting white dwarfs in dwarf novae below the period gap.
Abstract Copyright:
∼
Journal keyword(s):
Accretion, Accretion Disks - Stars: Binaries: Close - Stars: Novae, Cataclysmic Variables - Stars: Individual: Constellation Name: WW Ceti - Stars: Individual: Constellation Name: EM Cygni - Stars: Individual: Constellation Name: CZ Orionis - Stars: White Dwarfs
Simbad objects:
32
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2003ApJ...582..352W and select 'bookmark this link' or equivalent in the popup menu