H α variability in the quiescent spectrum of the recurrent nova T Coronae Borealis

Abstract

The emission lines in the quiescent spectrum of the recurrent nova T Coronae Borealis are variable. Optical spectra recorded during the years 1985–90 show one full cycle of high and low states. After removing the slow variation, an orbital-phase-dependent variation becomes apparent in the H α line, with maxima around orbital phases 0 and 0.5. The slow variation indicates secular changes in the accretion disc possibly caused by a variable mass transfer rate. Orbital variations can be caused either by geometrical effects or a phase-modulated mass transfer rate. More detailed monitoring is needed to model the system.