Scientists uncover unusual galaxies in universe's past
Wednesday, 30 Apr 2008 12:59
Artist's impression of stars seen from a hypothetical planet in a distant ultradense galaxy
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Scientists say they have observed ultra compact galaxies in the universe's distant past.
Nine young, unusually dense galaxies were observed by researchers using the Hubble space telescope and the WM Keck Observatory on Mauna Kea, Hawaii.
Each weighs 200 billion times the mass of the sun and they are 5,000 light years across.
Despite being a fraction of the size of today's 'grown-up' galaxies they contain the same number of stars.
This is the equivalent of a human baby that is 20 inches long but weighs 180 pounds.
The galaxies also differ from today's equivalent as the stars in them are spinning around their galactic disks at about one million miles an hour compared to today's stars which travel at about half that speed.
Lead researcher Pieter van Dokkum of Yale University said the compact size of the galaxies is a "puzzle".
"No massive galaxy at this distance has ever been observed to be so compact, and it is not yet clear how one of these would build itself up to be the size of the galaxies we see today," he added.
Scientists hope to learn more about the galaxies by using the wide field camera three, which is scheduled to be installed on Hubble during a servicing mission later this year.
They say these studies could lead to a better understanding of the evolution of galaxies early in the life of the universe.