The Nature of the Recurrent Nova T Coronae Borealis: Ultraviolet Evidence for a White Dwarf Accretor

Abstract

Data from eleven years of IUE observations of T CrB during its quiescent phase suggest that a white dwarf accretor rather than a main-sequence star is the hot component of the system. The spectroscopic and photometric behavior of T CrB during the 1946 outburst actually supports the interpretation of a thermonuclear runaway event on a massive white dwarf, according to the criteria proposed by Webbink et al. (1987) The data on emission-line radial velocities, which indicated for the hot component of the system a mass higher than the Chandrasekhar limit, do appear to contradict this interpretation, but may not be reliable. If new and more accurate radial velocity measurements confirm that the companion of the giant is on the order of 1.8 solar masses, then a triple system model for T CrB might be plausible. The giant's companion could be a normal nova composed of a massive WD and a 0.5 solar mass low-luminosity main-sequence star practically undetectable in the giant's light.