Ever saw a death dance? Have a look at this one

Two orbiting white dwarfs radiate gravitational waves, as seen in an artist's conception.

A pair of aging stars discovered 3,000 light-years away is locked in a "dance" of death—a union that will end in their collision and a possible supernova, astronomers say.

The binary star system consists of two white dwarfs—the burnt-out cores of sunlike stars. The white dwarfs are gradually spiraling toward each other at breakneck speeds of 370 miles (595 kilometers) a second, and they're destined to merge in 900,000 years.

"What is so incredible is that this exotic pair of Earth- and Neptune-sized stars are orbiting each other at only a third of our Earth-moon distance, circling each other every 12 minutes," said study leader Warren Brown, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

"And because there is no interaction—or star matter streaming between them—we may have a unique stellar laboratory here to look for effects of general relativity and probe for extreme gravity."
But the newfound star pair is unique in that they don't swap matter as they spin, providing a "clean clock" to measure the effects of gravitational waves, Brown said.



"There are lots of stellar pairs in the universe, but all are interacting and exchanging matter with one another because they are so close together."

That "complicates their interpretation, because you typically don't see either star, except for the light coming from the matter that is going back and forth between the stars."
When the two newfound stars merge, according to current models, the result may be one supermassive white dwarf or an unusually faint stellar blast called an underluminous supernova.

"If this is the progenitor of these rare subclass of supernova, we expect to be finding these exotic pairs at the same frequency as the supernova. We'll have to wait and see what our survey comes up with," study leader Brown explained.

Initial measurements were made in March, but now the binary system has moved almost directly behind the sun from our perspective on Earth, making the pair currently invisible to telescopes.

"Stars merging in less than a million years is really a blink of an eye in cosmic time scales," Brown said. "Just the fact that we found something like this—and it exists—is interesting for astronomers."
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