Uncommon black hole eating a star spotted by NASA's Hubble and Chandra

A Hubble Space Telescope image of a pair of galaxies: NGC 6099 (lower left) and NGC 6098 (upper right). The purple blob depicts X-ray emission from a compact star cluster. The X-rays are produced by an intermediate-mass black hole tearing apart a star. (Image: NASA)

Something small yet powerful is hiding in deep space. A rare black hole has been spotted feeding on a star, 450 million light-years away. The discovery came thanks to NASA’s Hubble and Chandra telescopes, working together across wavelengths.

A Bright Flash Caught Their Attention
The object, named NGC 6099 HLX-1, first appeared in 2009. Chandra caught the bright X-ray flash near the galaxy’s outskirts. It lies 40,000 light-years from the centre of NGC 6099, a giant elliptical galaxy in Hercules. Hubble later confirmed a cluster of stars around the black hole.

The black hole is not massive or tiny. It may be what scientists call an intermediate-mass black hole (IMBH). These are rarely seen because they feed quietly. But when they eat a star, they shine brightly for a short time. The black hole likely tore apart a passing star. The hot gas formed a disc and sent out intense radiation.

The temperature near HLX-1 reached 3 million degrees. That is typical of tidal disruption events. The brightness peaked in 2012, then faded slowly to 2023. The decline pattern gives clues about how such black holes behave.

Rare Objects Offer Key Black Hole Clues
IMBHs might be the missing step in black hole growth. They could help explain how supermassive black holes form. Some theories say large black holes grow by merging many small ones. Others think giant gas clouds collapsed directly into huge black holes. These new finds could help compare both ideas.

Astronomers believe HLX-1 could be orbiting in the galaxy’s outer halo. It is far from the galaxy's central black hole, which is currently quiet. If IMBHs exist in groups like this, galaxies may have more than one black hole.

More Discoveries Could Be on the Way
Spotting these events is still difficult. Telescopes like Chandra and XMM-Newton cover only small sky sections. But help is coming. The Vera C. Rubin Observatory in Chile will scan wide skies for bright flashes. Follow-up checks from Hubble and Webb could confirm more IMBHs.

The team says more tidal events could reveal the true number of IMBHs. Watching them could show how often they feed, how they grow, and how galaxies have changed over time.

It’s a rare peek into how the universe builds its darkest objects—one flare at a time.