"Missing link" black hole discovered by astromers.

Artist's impression of a cosmic homicide in action, with a wayward star being shredded by the intense gravitational pull of a black hole that contains tens of thousands of solar masses.

The Hubble Space Telescope is tracking down a suspected black hole that shredded a wayward star that came too close for comfort.

Background

The famed space observatory made the find while hunting down the source of a powerful burst of X-rays caught in 2006 by two other cosmic telescopes: NASA's Chandra X-ray Observatory and the European Space Agency's X-ray Multi-Mirror Mission (XMM-Newton) .

Details

Ø At the time, astronomers weren't sure if the X-rays had come from inside or outside of the Milky Way galaxy, but new high-resolution photography by Hubble shows that the X-ray source (known as 3XMM J215022.4−055108) is located in a star cluster at the edge of another galaxy.

Ø The team's work further suggests the star cluster may have been the core of a small dwarf galaxy disrupted long ago, when the dwarf galaxy strayed too close to the larger galaxy that currently hosts the star cluster.

Ø Gravitational interactions with the larger galaxy may have ripped the dwarf galaxy apart, leaving only a small cluster of stars in its wake.

Ø In much the same way, astronomers believe that the gravitational pull of the black hole inside this cluster shredded a star that got too close, thereby producing the X-ray flare detected in 2006.

Ø IMBHs have been particularly difficult to find because they are smaller and less active than supermassive black holes; they do not have readily available sources of fuel, nor as strong a gravitational pull to draw stars and other cosmic material which would produce telltale X-ray glows.

Ø IMBHs are believed to be a "missing link" in our understanding of how black holes evolve. Astronomers have seen many examples of small black holes that are similar in size to a star, and other examples of much larger black holes that typically reside in the centers of galaxies.

Ø But IMBHs remain difficult to confirm as astronomers struggle to understand how supermassive black holes got so big, compared to stellar-sized black holes.

Ø Hubble also helped track down another possible IMBH in 2009. The object, called HLX-1, was spotted on the edge of a galaxy known as ESO 243-49, and also resides in a star cluster that could have been a dwarf galaxy in the ancient past.

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