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More Andromeda Galaxy

September 17, 2015

A tiny star in the Andromeda galaxy may be about to put on a big show. Sometime soon, the star could explode as a supernova. For a few weeks or months, it could shine as bright as billions of normal stars.

The star is a white dwarf — the dead core of a once-normal star like the Sun. Unlike the Sun, though, this star has a big, puffy companion. The white dwarf is pulling gas off the surface of the companion. As the gas piles up, it triggers a nuclear explosion. Some of the material is blasted out into space, making the system shine tens of thousands of times brighter than normal.

Astronomers first spotted such an outburst from the system in 2008. And since then, they’ve seen similar eruptions every year except 2010.

That could mean that the white dwarf is reaching a tipping point. So much extra gas could be building up on its surface that it just can’t get rid of it all. Eventually, the star will pass a point of no return — it’ll get so massive that it can no longer support itself.

When that happens, the white dwarf will stage one final blast — a supernova. It’ll blast the star to cosmic dust. For a brief time, it could shine bright enough to see with the unaided eye — even though the Andromeda galaxy is two-and-a-half million light-years away.

Astronomers aren’t sure just when that’ll happen, but they know it’ll be soon: perhaps in a hundred thousand years — or perhaps as soon as tonight.

Tomorrow: moons that share.

Script by Damond Benningfield, Copyright 2015

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