December 22, 2011
Rare Massive Galaxy From Early Stages Of Universe Creating Massive Numbers Of Stars
A team of astronomers lead by Masami Ouchi of the University of Tokyo has found the most vigorous star-forming galaxy yet seen, from a period of time in the early stages of the creation of the universe known as ℠cosmic dawn´.
The 750-million-year-old galaxy, known as GN-108036 among was forming stars equivalent to about a hundred Suns per year, when most of the universe was still cold and dark, reports Rob Waugh for Mail Online.
The galaxy, 12.9 billion light-years away, was discovered and confirmed using ground-based telescopes but used data from the Spitzer and Hubble telescopes to measure the galaxy´s high star production rate. As a reference, our Milky Way galaxy is about five times larger and 100 times more massive than GN-108036, but makes roughly 30 times fewer stars per year.
According to the researches, GN-108036 may be a special, rare object that they happened to catch during an extreme burst of star formation. The discovery surprised astronomers because no previous galaxies this bright were found so early in the history of the universe.
“The significant finding about GN-108036 is that it demonstrates the existence of a vigorous star-forming galaxy when the universe was still very cold and dark,” team leader Ouchi said.
Back when galaxies were first forming, in the first few hundreds of millions of years after the Big Bang, they were much smaller than they are today, having yet to bulk up in mass. The relatively small size of the galaxy surprised astronomers with its prodigious output of stars from such an early era.
Hydrogen atoms permeated the cosmos and formed a thick fog that was opaque to ultraviolet light during this early epoch, as the universe expanded and cooled after its explosive start.
This period, before the first stars and galaxies had formed and illuminated the universe, is referred to as the “dark ages.” The era came to an end when light from the earliest galaxies burned through, or “ionized,” the opaque gas, causing it to become transparent.
“The high rate of star formation found for GN-108036 implies that it was rapidly building up its mass some 750 million years after the Big Bang, when the universe was only about five percent of its present age,” said Mobasher, a professor of physics and astronomy. “This was therefore a likely ancestor of massive and evolved galaxies seen today.”
Researchers from the University of California - Riverside also contributed to this finding.
Image Credit: NASA, ESA, JPL-Caltech, STScI, and the University of Tokyo
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