NASA Hubble Spots a Relic from a Shredded Galaxy

Astronomers using NASA's Hubble Space Telescope may have found evidence for a cluster of young, blue stars encircling HLX-1, one of the first intermediate-mass black holes ever discovered.

Astronomers believe the black hole may once have been at the core of a now-disintegrated dwarf galaxy.

The discovery of the black hole and the possible star cluster has important implications for understanding the evolution of supermassive black holes and galaxies.

This spectacular edge-on galaxy, called ESO 243-49, is believed to be home to an intermediate-mass black hole that may have been stripped off of a cannibalized dwarf galaxy. The estimated 20,000-solar-mass black hole lies above the galactic plane.

This is an unlikely place for such a massive back hole to exist, unless it belonged to a small galaxy that was gravitationally torn apart by ESO 243-49. The circle identifies a unique X-ray source that pinpoints the black hole.

The X-rays are believed to be radiation from a hot accretion disk around the black hole. The blue light not only comes from a hot accretion disk, but also from the possible existence of a cluster of hot young stars that formed around the black hole.

The galaxy is 290 million light-years from Earth. Hubble can't resolve the stars individually because the suspected cluster is too far away. Their presence is inferred from the color and brightness of the light coming from the black hole's location.