Betelgeuse, the second-brightest star in the familiar constellation Orion, is a strange, giant star. Recent observations have revealed that it spins much faster — and has many more heavy elements mixed within it — than typical giant stars should. Recently, a team of astronomers developed a sophisticated computer simulation to explore a radical idea: That Betelgeuse is the result of a merger between two smaller stars.
All stars follow well-understood evolutionary tracks. They fuse hydrogen in their cores for the vast majority of their lives, leaving behind a buildup of helium as they age. Changing the ratio of hydrogen to helium in the core affects the rest of a star's properties, like its size, brightness and temperature. For example, when more massive stars like Betelgeuse near the ends of their lives, they develop so much helium in their cores that hydrogen fusion moves into a shell surrounding that core, inflating the rest of the star into a red supergiant.
