Identification of the Long-Sought Common-Envelope Events

Abstract

When Stars Get Too Close: Stellar outbursts used to come in two classes: supernovae and novae, the complete explosions and the thermonuclear runaways on the surface of evolved stars, respectively. Over the past two decades a class of stellar outbursts emerged with luminosities between those of novae and supernovae—intermediate-luminosity red transients (ILRTs). Ivanova et al. (p. 433 ) propose that these ILRTs are the signature of common envelope events in which a lower-mass star in a close binary system is engulfed by matter transferred from its more massive and more evolved companion star.