clipped from: www.abc.net.au   

Astronomers say they have spotted a new type of stripped-down white dwarf star with a pulsating carbon surface.

exploding white dwarf

The new and so far unique white dwarf was predicted to exist somewhere in the cosmos, but was found only because of extensive sky surveys.

"They're extremely rare," says astronomer Dr Kurtis Williams of the University of Texas at Austin's McDonald Observatory, where the discovery was made.

"It's a real needle in a haystack to find one."

The white dwarf star they discovered is 800 light-years away in the constellation Ursa Major, or the Big Dipper.

Unlike other white dwarfs, however, this one has been stripped of its outer layers of hydrogen and helium and is left with carbon on its surface
at a very toasty 19,500°C, which allows its carbon to shift en masse between a higher and a lower energy state, driven by just one electron per atom. That shifting carbon is visible as the star pulsating
Other white dwarfs have been found pulsating, but they are doing it with hydrogen and helium