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Session 85 - Cataclysmic Variables and Accretion Disks.
Oral session, Wednesday, January 15
Harbour A,

[85.06] On the Relative Rates of Decay of the Optical and Soft X-ray Fluxes in Dwarf Nova Outbursts

We present time dependent computations utilizing the accretion disk limit cycle instability to model the decay of the flux in dwarf nova outbursts. In particular, we model the optical and 0.1 keV fluxes in an attempt to account for recent findings by Ponman et al. The e-folding decay times of \sim3 d for the optical and \sim1 d for the soft X-ray/EUV in an outburst of SS Cygni are naturally accounted for in the model by the action of the cooling front which enacts the transition between the high and low states in the accretion disk. The difference in time scales between V and EUV stems from the fact that, roughly speaking, the optical flux samples the surface area of the hot part of the accretion disk, whereas the EUV samples the mass of the hot part of the accretion disk.

This work was supported under the visiting scientist program of the Universities Space Research Association (USRA contract NAS5-32484) in the Laboratory for High Energy Astrophysics at Goddard Space Flight Center.

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