A University of Alberta professor has revealed the workings of a celestial event involving binary stars that produce an explosion so powerful its luminosity ranks close to that of a supernova, an exploding star. Theoretical astrophysicist Natalia Ivanova says researchers have long debated about what happens when binary stars, two stars that orbit one another, come together in a "common envelope." Read more
Title: Identification of the Long-Sought Common-Envelope Events Authors: N. Ivanova, S. Justham, J. L. Avendano Nandez, J. C. Lombardi Jr
Common-envelope events (CEEs), during which two stars temporarily orbit within a shared envelope, are believed to be vital for the formation of a wide range of close binaries. For decades, the only evidence that CEEs actually occur has been indirect, based on the existence of systems that could not be otherwise explained. Here we propose a direct observational signature of CEE arising from a physical model where emission from matter ejected in a CEE is controlled by a recombination front as the matter cools. The natural range of timescales and energies from this model, as well the expected colours, light-curve shapes, ejection velocities and event rate, match those of a recently-recognised class of red transient outbursts.