Cannibal Stars

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Cannibal Stars

At heart, just about every star is a potential cannibal. Stars that travel through space alone don’t get the chance to act on that instinct. But those with close companions sometimes do act on it. They can pull gas from the companion, eventually leaving the companion with no more than its hot core.

A recent study found a handful of such systems. Three of them are in Cygnus, the swan. One example is called 60 Cygni.

Its two stars are about as far apart as Mars and the Sun. The main star appears to be more than 10 times as massive as the Sun. It’s also much hotter and brighter than the Sun. The companion appears to be a stripped-down core — its outer layers have been cannibalized by the heavy star.

When the system was born, the stripped star probably was the more-massive member. As it reached the end of the prime phase of life, it puffed up. That allowed the companion to start pulling away some of the dying star’s outer layers of gas. Eventually, all of the material in the outer layers might have been transferred to the other star, making it the bigger member of the duo.

In time, that star will begin to expand as well. So the stripped-down companion may begin to pull away its outer layers — cannibalizing the cannibal.

Cygnus is low in the northeast not long after the sky gets good and dark. But you need binoculars or a telescope to find its possible cannibals.

Script by Damond Benningfield

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