, 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: Thatfollow 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.
As the supergiant star aged, its atmosphere extended to the orbit of its companion, the simulation revealed. The companion star'sfunneled that material onto itself, increasing its own mass. Eventually, the companions started swimming through so much material that this caused friction, thus slowing the companion and drawing it inward.
However, Betelgeuse retained a memory of the collision. In the astronomers' model, the merger mixed up the contents of the star, sending heavier elements, like nitrogen, into the upper reaches of the atmosphere, where some of it remains visible today. And the merger added a significant amount of rotational energy to Betelgeuse. While the star presumably slowed down somewhat since that theoretical violent merger, it's still rotating much faster than it should be.