July 11, 2008 -- A distant galaxy is churning out stars at a prodigious rate of up to 4,000 a year, new observations show, in a finding that has left astronomers wondering if the generally accepted theory of galaxy formation is actually true.
Our own Milky Way galaxy, in comparison, creates about 10 new stars annually.
Scientists say it is not just the rate of new star formation that is puzzling; it's that fact that the star-booming galaxy dates back to a time when the universe was only about 1.3 billion years old.
"Before now, we had only seen galaxies form stars like this in the teen-aged universe, but this galaxy is forming when the universe was only a child," said Peter Capak, with the California Institute of Technology in Pasadena, Calif.
"The question now is whether the majority of the very most massive galaxies form very early in the universe, or whether this is an exceptional case," he added.
The discovery, reported in this week's Astrophysical Journal Letters, was made after observations by several ground- and space-based telescopes.
First, visible light images were taken by the Hubble Space Telescope and Japan's Subaru Telescope in Hawaii. Later, studies of infrared wavelengths were made by the Spitzer Space Telescope and of sub-millimeter radio waves by the James Clerk Maxwell Telescope in Hawaii. These results uncovered the bright, hot stars which had been obscured by dust.
Finally, scientists used the Very Large Array radio observatory in New Mexico to calculate the galaxy's rate of star formation.
"We may be witnessing, for the first time, the formation of one of the most massive elliptical galaxies in the universe," concludes Nick Scoville, a CalTech astronomer and a co-author of the study.
If the galaxy, nicknamed Baby Boom, continues making stars at such high rates, within 50 million years -- just a blink in astronomical time scales -- it could become one of the most massive known galaxies in the universe.
The currently held theory of galaxy formation postulates that galaxies build up their stars over time as they slowly annex passing real estate. The Baby Boom galaxy is producing most of its stars all at once, Capak said.
"If our human population were produced in a similar boom, then almost all of the people alive today would be the same age," he said.
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