The secondary outburst maximum of T Coronae Borealis - Implications for the physics of accretion disks

Abstract

The hypothesis of Webbink (1976) that the accretion of a torus of matter onto a main-sequence star caused secondary maxima during the 1866 and 1946 eruptions of the recurrent nova T CrB is examined. Simple 1D calculations show that the accretion disk viscosity must increase with time to produce light curves resembling observations. It is inferred that the physical mechanism responsible for producing the viscous dissipation in the accretion disk has a fast growth rate and saturates to a viscosity parameter of order unity. The good agreement between parameters estimated from observations and those derived from a physical mechanism suggests that the growth rate instability identified by Balbus and Hawley (1991) is a promising source for accretion disk viscosity.