Modeling the Heating and Cooling of WZ Sagittae following the July 2001 Outburst

Abstract

FUSE and HST/STIS spectra of the dwarf nova WZ Sge, obtained during and following the early superoutburst of July 2001 over a time span of 20 months, monitor changes in the components of the system during its different phases. The synthetic spectral fits to the data indicate a cooling in response to the outburst of about 12,000K, from about 28,000K down to about 16,000K. The cooling time scale tau (of the white dwarf temperature excess) is of the order of about 100 days in the early phase of the cooling period, and increases to about 850 days toward the end of the second year following the outburst. In the present work, we numerically model the accretional heating and subsequent cooling of the accreting white dwarf in WZ Sge. The best compressional heating model fit is obtained for a 1.2 Msun white dwarf accreting at a rate of 9.E-9 Msun/yr for 52 days. However, if one assumes a lower mass accretion rate or a lower white dwarf mass, then compressional heating alone cannot account for the observed temperature decline, and other sources of heating have to be included to increase the temperature of the model to the observed value. We quantitatively check the effect of boundary layer irradiation as such an additional source.

arXiv commentto appear in ApJ, 602, Feb. 10 2004 issue

References in corpus (4)

• The 2001 Superoutburst of WZ Sagittae
• WZ Sge: FUSE Spectroscopy of the 2001 Outburst
• Discovery of 15-second oscillations in Hubble Space Telescope observations of WZ Sagittae following the 2001 outburst
• Measuring the Boundary Layer and Inner Accretion Disk Temperatures for WX Ceti During Superoutburst

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