Rigel — the brightest star of Orion, the hunter — is pretty complicated. It’s going through a series of changes in its core that will make it grow much bigger and brighter. Its surface jiggles like a Jell-O mold. And it’s blowing a “wind” of hot gas into space — enough material every million years to make one or two stars as big as the Sun. All of this activity is a result of Rigel’s great mass — more than 20 times the mass of the Sun. Such heavy stars burn through the nuclear fuel in their cores in a hurry, so they live short lives. Rigel is only a fraction of one percent of the age of the Sun, yet it’s already nearing the end of its life. The star has consumed the hydrogen in its core to make helium. The core is now shrinking and getting hotter. Eventually, it’ll get hot enough to start burning the helium. Right now, nuclear reactions are taking place in a shell of hydrogen around the core. They make the star’s surface jiggle, with each jiggle lasting anywhere from a day to more than
