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Astronomers have spotted the "greenest" of galaxies, one that converts fuel into stars with almost 100-percent efficiency.

The findings come from NASA's Wide-field Infrared Survey Explorer (WISE), NASA's Hubble Space Telescope and the IRAM Plateau de Bure interferometer in the French Alps.

"This galaxy is remarkably efficient," said Jim Geach of McGill University in Canada, lead author of a new study appearing in the Astrophysical Journal Letters. "It's converting its gas supply into new stars at the maximum rate thought possible."

Stars are formed out of collapsing clouds of gas in galaxies. In a typical galaxy, like the Milky Way, only a fraction of the total gas supply is actively forming stars, with the bulk of the fuel lying dormant. The gas is distributed widely throughout the galaxy, with most of the new stars being formed within discrete, dense 'knots' in the spiral arms.

In the galaxy, called SDSSJ1506+54, nearly all of the gas has been driven to the central core of the galaxy, where it has ignited in a powerful burst of star formation.

"We are seeing a rare phase of evolution that is the most extreme -- and most efficient -- yet observed," said Geach.

The results will provide a better understanding of how the central star-forming regions of galaxies take shape.

SDSSJ1506+54 jumped out at the researchers when they looked at it using data from WISE's all-sky infrared survey. Infrared light is pouring out of the galaxy, equivalent to more than a thousand billion times the energy of our sun. The galaxy is so distant it has taken the light nearly six billion years to reach us.

"Because WISE scanned the entire sky, it detected rare galaxies like this one that stand out from the rest," said Ned Wright of UCLA, the WISE principal investigator.

Hubble's visible-light observations revealed that the galaxy is extremely compact, with most of its light emanating from a region just a few hundred light-years across. That's a big star-making punch for such a little size.

"While this galaxy is forming stars at a rate hundreds of times faster than our Milky Way galaxy, the sharp vision of Hubble revealed that the majority of the galaxy's starlight is being emitted by a region with a diameter just a few percent that of the Milky Way," said Geach

Read More: Sciencedaily

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