JUANA SUMMERS, HOST:
Our closest star, the sun, is moving through space, going about a half a million miles per hour. Now, that may seem fast, but some stars in our galaxy go way faster than that. And as NPR's Nell Greenfieldboyce reports, it turns out that some of these speedy stars were hurled through space by a massive black hole that's been hiding nearby.
NELL GREENFIELDBOYCE, BYLINE: Hypervelocity stars go at ridiculous speeds, like several million miles per hour. They go so fast, they have achieved escape velocity. They are saying goodbye to the Milky Way, unlike our slowpoke sun, which orbits our galaxy's center.
JESSE HAN: These stars are moving too fast to sustain such an orbit. They're just on their way out. They're never going to come back again.
GREENFIELDBOYCE: Jesse Han is an astronomer with the Harvard and Smithsonian Center for Astrophysics. He says hypervelocity stars start out as normal stars - normal stars that are part of a binary system. That's two stars orbiting each other. But if this happy pair ventures too close to a powerful black hole...
HAN: What can happen is one of the stars can get captured by the black hole, so it is basically ripped apart from its companion.
GREENFIELDBOYCE: And the surviving companion star goes flying off. Han and some colleagues recently used a space telescope called Gaia to study 21 hypervelocity stars. They traced the stars' paths backwards.
HAN: The sort of common wisdom was they should all come from our galactic center, where we know with certainty that there is a supermassive black hole.
GREENFIELDBOYCE: And about half of them did. But it turns out the rest came from our closest neighboring galaxy, the Large Magellanic Cloud. Han says this means that galaxy must contain a monster black hole that's about 600,000 times the mass of our sun. And now that researchers know that...
HAN: The search is on, and we're using all the telescopes we can to look for it.
GREENFIELDBOYCE: This would be the closest giant black hole outside of our galaxy, a cosmic beast that's been lurking unseen right next door.
Nell Greenfieldboyce, NPR News.
(SOUNDBITE OF MUSE SONG, "SUPERMASSIVE BLACK HOLE")
Copyright © 2025 NPR. All rights reserved. Visit our website terms of use and permissions pages at www.npr.org for further information.
NPR transcripts are created on a rush deadline by an NPR contractor. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.