The Secondary Star in AM CVn

Abstract

The spectrum of AM CVn shows no definite sign of a secondary star, but through black body calculations of the spectra of the primary, disc and secondary objects, we find that if a one-temperature model for the secondary is assumed, a secondary which is cooler than 5000 K may be present without being seen in the spectrum. There is some excess flux in the visible part of the spectrum, which indicates the presence of an object of approximately 10 000 K. The best fit is given by a two- temperature model of the secondary, indicating that illumination of the secondary by the hot primary and the disc is an important effect.