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HubbleSite Hubble Uncovers a Galaxy Pair Coming in from the Wilderness


Space Telescope Science

The galaxies in the early universe were much smaller than our Milky Way and churned out stars at a rapid pace. They grew larger through mergers with other dwarf galaxies to eventually build the magnificent spiral and elliptical galaxies we see around us today. But astronomers using the Hubble Space Telescope have looked at two small galaxies that were left off the star party list. For many billions of years Pisces A and Pisces B lived in a vast intergalactic wilderness that was devoid of gas, which fuels star formation. They got left out in the cold.

Better late than never. Like Rip van Winkle awakening from a long slumber, the dwarf galaxies have now ended their star-making drought and have joined the party. Astronomers estimate that less than 100 million years ago the galaxies doubled their star-formation rate. For most of the universe's history these puny galaxies dwelled in the Local Void, a region of the universe sparsely populated with galaxies. Now the galaxies have moved into a region crowded with galaxies and full of intergalactic gas. This dense environment is triggering star birth.

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