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The Hubble Space Telescope has discovered two spiral galaxies that collided and created a black hole, a quasar and at least six star clusters that emit more energy than any seen before.

Astronomers announced Tuesday that a study by the Hubble shows that what was once believed to be an obscure galaxy called Arp 220 is really the dusty and violent collision of two massive galaxies. The discovery came from the Hubble's wide-field camera and a study by Edward Shaya and Dan Dowling of the University of Maryland.Steve Maran, an astronomer at the National Aeronautics and Space Administration's Goddard Space Flight Center, said the Hubble detected at least six star clusters - or collections of billions of stars - formed within the collided pair of galaxies, located 220,000 light years from Earth. He said the studies also reveal the presence of at least one black hole and an associated quasar.

Arp 220 was largely ignored by past astronomy studies because it appeared to be such an insignificant galaxy. But a 1983 study by the Infrared Astronomy Satellite showed that Arp 220 shone with dramatic brilliance in the infrared spectrum, which is not visible to the eye.

The Hubble study showed that the collision and other forces within Arp 220 have created so much dust and gas that about half of the infrared radiation and up to 99 percent of the visible light were being blocked from view. The light is heating up the dust and gas, and energy escapes as infrared, the study found.

By filtering out the effects of the dust, the Hubble study showed that the six star clusters were creating the light equivalent of about 90 billion suns each. The quasar was producing radiation about 400 billion times the light of the sun, Maran said.

"No star cluster previously seen has been this bright," said Maran. He said the clusters are brighter than some galaxies and are at least 10 times larger than any previously known star cluster.

The NASA astronomer said Arp 220 could become a factory for exploding stars, or supernovae, because it is believed that stars created in the clusters will be short-lived - only a few tens of millions of years - and will then explode with great violence.