Brain Food: Lowell Astronomers Discover a Rare Runaway Star

Apr 26, 2018

Astronomers at Lowell Observatory in Flagstaff have discovered a rare runaway star: a yellow supergiant. It’s the first time humans have ever observed one as it’s speeding through its galaxy at 300,000 miles per hour—so fast, it could cover the distance between L.A. and New York in 30 seconds. Here’s Lowell astronomer Phil Massey.

An artist's rendering of a binary star system including a yellow hypergiant.

“So, what we think happened in the case of our runaway, there were two massive stars in orbit around each other. The more massive one evolves more quickly and expanded into a red supergiant phase and then exploded in a supernova. When that happened, all of this mass would have been lost from the system. And our star, the one that’s going to turn into a yellow supergiant runaway, would suddenly be flung off into space because there would be nothing holding it in place anymore and then after another 30 million years, our star evolved into a yellow supergiant,” he says.

The yellow supergiant phase is brief in the life of a star, less than 100 thousand years. Kathryn Neugent heads up the astronomy research team at Lowell. She says they noticed it nearly a decade ago, but dismissed it as insignificant.

“Nine years later at this point, we decided to go back and look at this star and get some more spectra, and actually found it was something really exciting. It wasn’t in a binary system and it is this runaway yellow supergiant star. So it was pretty exciting when we actually discovered that the star was something interested as opposed to just a random star in a binary system,” she says.

Astronomers say this particular supergiant is 200 times bigger than our sun. When it eventually dies in a spectacular explosion, the dust and gas released could form new stars and planets.