Boundary-layer temperatures in high accretion rate cataclysmic variables

Abstract

The Zanstra method is used to derive limits on boundary-layer temperatures in eclipsing dwarf novae during outburst and nova-like variables, using the observed He II 1640 and 4686 A recombination lines. It is assumed that all the emission is produced in the wind rather than the accretion disk. This method constrains the boundary-layer temperatures to between 50,000 and 100,000 K, depending on the degree of wind bipolarity. These estimates are lower than the T in excess of 200,000 K predicted theoretically. Possible explanations include rapid rotation of the white dwarf and spreading of the boundary layer over the entire white-dwarf surface.