The Chandra LETG spectrum of SS Cyg in outburst shows broad (≈ 5 Å) spectral features that have been interpreted as a large number of absorption lines on a blackbody continuum with a temperature of 250 kK (Mauche 2004). It is most probable that this is the spectrum of the fast-rotating optically thick boundary layer on the white dwarf surface. Here we present the results of fitting this spectrum with high gravity hot stellar model atmospheres. An extended set of LTE model atmospheres with solar chemical composition was computed for this purpose. The best fit is obtained with the following parameters: Teff = 190 kK, log g = 6.2, and NH = 8·1019 cm-2. The spectrum of this model describes the observed spectrum in the 60-125 Å range reasonably well, but at shorter wavelengths the observed spectrum has much higher flux. The reasons for this are discussed. The derived low surface gravity supports the hypothesis of the fast rotating boundary layer.
18th European White Dwarf Workshop.
- Pub Date:
- January 2013
- Astrophysics - High Energy Astrophysical Phenomena
- 6 pages, 5 figures, to be published in the proceedings of the 18th European White Dwarf Workshop