Comet Enthusiast

"The question of what causes a Type Ia supernova is one of the great unsolved mysteries in astronomy," said Rosanne Di Stefano of the Harvard-Smithsonian Center for Astrophysics.

A subset of supernovas called Type Ia supernovas are thought to erupt when a dense, dim star called a white dwarf hits a certain upper limit in mass and explodes. But astronomers are still confused by just what cases white dwarfs to hit that mass limit and explode.

"The question of what causes a Type Ia supernova is one of the great unsolved mysteries in astronomy," said researcher Rosanne Di Stefano of the Harvard-Smithsonian Center for Astrophysics.

To get to the bottom of the mystery, scientists have been searching for white dwarfs in the stage before they get massive enough to explode, searching for so-called "super-soft" X-rays, which are thought to be created when gas from one star hits another star's surface and undergoes nuclear fusion.  Yet for some reason, scientists have only been able to find a handful of these X-ray sources, where they expected to find hundreds.

Di Stefano suggests that some process is blocking this light from reaching our telescopes on Earth. Perhaps some other material surrounding the white dwarf absorbs the X-rays after they are emitted so we can't see them, or that they emit most of their light at wavelengths other than X-rays.

"We must devise new methods to search for the elusive progenitors of Type Ia supernovae," Di Stefano said.