Two White Dwarf Stars Collided and Came Back from the Dead. Soon, They'll Go Supernova.
By Brandon Specktor, Senior Writer | May 23, 2019 02:16pm ET
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n this hazy nebula about 10,000 light-years from Earth, astronomers think they've found a star that came back from the dead thanks to a rare event called a double white dwarf merger. Soon, it could die again in a supernova explosion.
Credit: Vasilii Gvaramadse/Moscow University
Astronomers have discovered a star they believe has come back from the dead.
The star, located in a hazy nebula in the constellation Cassiopeia, is unlike most other stars. It shows no signs of hydrogen or helium the two lightest elements in the universe and the final source of fuel for the nuclear reactions that power the hearts of stars. Despite this, it glows tens of thousands of times brighter than Earth's sun, and howls with a stellar wind that seems to have the strength of two stars.
Perhaps, write the authors of a new study published May 20 in the journal Nature, that's because this oddball star once was two stars and two dead ones, at that. After some careful analysis of the star and the gassy nebula that surrounds it, the study authors determined that the star's unusual properties can be best explained by a rare phenomenon known as a double white dwarf merger. Essentially, two burnt-out stars got too close and collided, accumulated enough combined mass to start forging heavy elements again, and reignited. [The 12 Strangest Objects in the Universe]
"Such an event is extremely rare," study co-author Götz Gräfener, an astronomer at the Argelander Institute for Astronomy (AIfA) at the University of Bonn in Germany, said in a statement. "There are probably not even half a dozen such objects in the Milky Way, and we have discovered one of them."
More:
https://www.livescience.com/65550-dead-stars-revived-white-dwarf-merger.html