In a science article that reads like a vampire story, researchers found a massive hot star that looked like the kind of giant that should only live for five million years, but this star was located so far from any potential stellar nursery that no one could explain it. Moving at normal orbital rates, this object couldn’t have lived long enough to travel the 3,600 light-years between it and the disk of the Milky Way. In trying to figure out how this young-looking star got to the far-off location, researchers realized the star, HD93521, didn’t form as one massive star, but rather as two smaller stars that traveled and aged together as a binary star system.

Until they didn’t.

At some point, the stars merged together, with one star consuming the other and rolling back its clock to become young again.

HD93521 gave away its murderous past with its spin. Pretty much everything in the universe spins, but it takes a violent event or a merger of some sort to get something spinning fast, and HD93521 happens to be one of the fastest spinning regular stars in the galaxy.

And it looks like HD93521 may be a trendsetter. The steller pair IT Librae is also zipping out of the disk of the galaxy, and one of its two stars looks entirely too young to have been able to make this journey. A close look reveals that the smaller star is being robbed of its mass, allowing the growing companion to appear younger and younger as they journey.

This work appears in a new paper in The Astronomical Journal, is led by Douglas Gies, and it concludes with one final bit of horror science. It turns out that these merged stars can evolve into fast rotating black holes.

More Information

Georgia State press release

“The Transformative Journey of HD 93521,” Douglas R. Gies, Katherine Shepard, Peter Wysocki, and Robert Klement, 2022 January 31, The Astronomical Journal