White dwarfs
© H Bond (STScI), R Ciardullo (PSU), WFPC2, HST/ NASAWhite dwarfs - small, dense, dying stars - may be hiding a dark secret.

The brightness of white dwarfs may point towards the existence of exotic dark matter particles.

Jordi Isern of the Institute of Space Sciences in Bellaterra, Spain, and colleagues modelled what would happen if white dwarfs - small, dense, dying stars - were emitting axions. These hypothetical particles are a candidate for dark matter, which makes up most of the universe.

The model showed that axion emission affected a white dwarf's brightness, and the distribution of stars of a given luminosity predicted by the model matched well with observations of 6000 white dwarfs by the Sloan Digital Sky Survey. This is the first indication that axions could exist, say the team.