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Stellar Kiss

December 28, 2017

Two stars in the constellation Cancer look like they’re puckering up for a kiss. And in a way, they are — the stars are about to make contact.

One star in the system is bigger, heavier, and brighter than the Sun. The other is smaller and fainter than the Sun. The stars orbit each other once every 11 hours.

A team of astronomers has been watching the system for 15 years. The observations show that each star is bulging toward the other. That makes the system look like a pair of teardrops, with the tapered ends aiming toward each other — like two cartoon characters getting ready for a smooch.

Before long, the stars may make contact. Both stars are quite bloated. The bigger star has puffed up as much as it can. But the other has a little room left to reach its maximum size. So right now, the tips of the teardrops are separated by a few thousand miles. Once the second star is fully inflated, though, the two stars will likely make contact.

The stars then will begin to share the gas in their outer layers. Eventually, they’ll merge to form a single star. That may produce an outburst known as a red nova. After that, the merged system should settle down. The single star will be bright and hot, and it’ll be spinning rapidly — the result of a stellar coalescence that begins with a kiss.

The system is too faint to see with the eye alone. But its constellation, Cancer, rises in the east by around 9 p.m., and climbs high across the sky later on.


Script by Damond Benningfield

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