Using a computer model, astronomers in Japan present evidence to support one theory about the origin of type Ia supernovae, which are of predictable luminosity and are therefore useful for estimating distances to remote galaxies. These supernovae are generated when a compact star called a carbon–oxygen white dwarf siphons off a critical amount of matter from a companion star. However, astronomers have yet to directly observe a companion star.

Izumi Hachisu at the University of Tokyo and his team offer a solution to this conundrum. Their model, which accounts for the rotation of white dwarfs, shows that many companion stars have evolved to a state too faint to be seen. The model is consistent with observations of supernova 2011fe.

Astrophys. J. 756, L4 (2012)