Astronomers have long been curious about how red supergiant stars, like the bright star, Betelgeuse, manage to shed so much matter into space.
Now, thanks to a collaborative effort which gave scientists a detailed view of the distant star's surface, they have an answer - it's boiling.
Observations with a trio of 1.8-meter radio telescopes show giant bubble-like structures bobbing on the surface of Betelgeuse, a massive star located 640 light-years away in the constellation Orion.
Emitting about 100,000 times more light than our sun, Betelgeuse is the bright orange star on the shoulder of Orion, also known as The Hunter.
The observations, which are being reported in an upcoming issue of Astronomy & Astrophysics, are the first to spatially resolve the motion of gas on the surface of a star other than the sun, said Keiichi Ohnaka, with the Max-Planck-Institut fur Radioastronomie in Bonn, Germany.
Ohnaka and colleagues found giant gas bubbles - some as large as the star itself - moving vigorously up and down in the star's atmosphere.