A cannibalistic star sounds like something fit for a sci-fi flick, but it’s a real thing. And it’s called a “blue straggler”.
Blue stragglers (also known as “vampire stars”) are nothing new. Then again, is anything “new” in a 13-billion-year-old universe? Astronomers have seen these vampires in various star clusters throughout the universe, but the star-munching stars had never been seen in the Milky Way until recently. Specifically, they were spotted in the galactic bulge of our galaxy, a region of dense stars and gas.
Astronomers determine the age of a star by looking at its mass and temperature. When a star is young, it burns hot and therefore appears bluer in colour. But when astronomers pointed Hubble toward the bulge, they found 42 unusually blue stars that seemed suspiciously young. While some may be legitimately young, it’s believed that around half of them are faking it.
So how do these stars succeed at cheating galactic death? Well, it seems these older vampire stars regain their youth by sucking the hydrogen from neighbouring stars. This causes them to appear bluer, younger and hotter. No one’s 100 per cent as to how these stars accomplish this, but they’ve got theories. One possibility is they were originally part of a two-star, or binary, system when the cannibal decided it was hungry and devoured its companion. Another theory is gravitational interactions caused two stars of a triple-star system to merge into one. What’s clear is that these stars are the galactic version someone undergoing their midlife crisis. And the jig is up. [National Geographic]