NASA telescopes spot star "factory"

WASHINGTON (Reuters) - Telescopes looking back in time to more than 12 billion years ago have spotted a star factory -- a galaxy producing so many new stars that they have nicknamed it the "baby boom" galaxy.

The remote galaxy is -- or was -- pumping out stars at a rate of up to 4,000 per year. In comparison, our own Milky Way galaxy gives birth to an average of just 10 stars per year, they reported on Wednesday.

"This galaxy is undergoing a major baby boom, producing most of its stars all at once," said Peter Capak of NASA's Spitzer Science Center at the California Institute of Technology.

"If our human population was produced in a similar boom, then almost all of the people alive today would be the same age," Capak said in a statement.

Writing in Astrophysical Journal Letters, Capak and colleagues said they used several telescopes including NASA's Spitzer Space Telescope and Hubble Space Telescope to spot the prolific ancient galaxy, which belongs to a class of galaxies called starbursts.

The galaxy is 12.3 billion light-years away. The universe is 13.4 billion years old, so the galaxy was pumping out stars when the universe was 1.3 billion years old.

A light-year is the distance light travels in one year.

"Before now, we had only seen galaxies form stars like this in the teenaged universe, but this galaxy is forming when the universe was only a child," said Capak. "The question now is whether the majority of the very most massive galaxies form very early in the universe like the Baby Boom galaxy, or whether this is an exceptional case."

(Reporting by Maggie Fox, editing by Will Dunham and Philip Barbara)