"GREEN PEA" PICTURES: New Galaxy Class Discovered

green pea galaxy pictures
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July 28, 2009—Do you want your peas fresh, frozen, canned, or spurting out stars at ten times the rate of the Milky Way?

Volunteers sifting through an online image bank called Galaxy Zoo have helped astronomers discover a new, rare class of galaxy dubbed the Green Pea.

The spotters—calling themselves the Peas Corps and the Peas Brigade—noticed that out of a million cosmic objects, 250 share a few odd traits: They're all tiny, round, and green.

This made the peas—including the three seen above—stick out when compared with more common Galaxy Zoo objects, like the one pictured at lower right.

With the help of Yale University Ph.D. student Carolin Cardamone, further research revealed that the tiny peas were more complicated than they first seemed.

"They looked like stars, but they had a positive redshift," Cardamone told National Geographic News. A higher redshift means that an object is farther away. The green peas lie between 1.5 and 5 billion light-years from Earth, so for us to be able to see them, the peas must be galaxies.

By analyzing light from the galactic peas, Cardamone then found that each green blob is forming stars at an exceptional rate. This surprised her, as the Green Peas are each about a hundred times less massive than the Milky Way.

Despite being relatively nearby lightweights, the Green Peas are "behaving just like early-universe galaxies are," she said.

This unusual new type of galaxy could therefore help astronomers better understand the early universe and how galaxies evolve.

Findings will be published in an upcoming issue of Monthly Notices of the Royal Astronomical Society.

—Rachel Kaufman

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