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Raging winds strip galaxies of gas

Raging winds up to 10,000 times more powerful than a terrestrial hurricane have been detected streaming away from galaxies and stripping them of star-forming gas, according to a new study.

The strongest winds, observed with the European Space Agency's Herschel infrared space observatory, reach up to 1,000 kilometers per second (2.2 million miles per hour).


The winds could be generated by the intense emission of light and particles from newly formed stars, the shockwaves of stellar explosions, or by the black holes at the center of galaxies, the agency notes in a media advisory.

The finding may help explain why some galaxies suddenly stop forming new stars. Scientists studying the data infer that about 1,200 times the mass of our sun is being lost each year from the galaxies with the most vigorous outflows. That is sufficient to strip them of star-forming gas in as little as a million years.

The fastest of the winds appear to come from galaxies that have the brightest galactic nuclei in which a black hole is feeding from its surroundings, a finding that could be a step towards explaining how elliptical galaxies are formed.

Elliptical galaxies are vast islands of stars that have stopped producing appreciable numbers of new stars because they have exhausted their gas supplies.

ESA explains that as smaller galaxies interact and merge with each other, more food is supplied to the central black hole, making it larger and more active. This, in turn, could result in a more powerful wind, which removes the molecular gas and halts star formation, leading to an elliptical galaxy.

The inhibition of star formation in a galaxy is known as negative feedback.

"By catching molecular outflows in the act, Herschel has finally yielded long-sought-after evidence that powerful processes with negative feedback do take place in galaxies and dramatically affect their evolution," Goran Pilbratt, ESA Herschel project scientist, said in the media advisory.

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'Massive molecular outflows and negative feedback in ULIRGs observed by Herschel-PACS,' by Sturm et al., is published in Astrophysical Journal Letters, vol. 733, page L16.

John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).