Galactic 'Blow Out' Shoots Dense Gas from a Compact Galaxy

For the first time, astronomers have witnessed the dramatic "blow out" phase of galactic evolution. They've discovered dense gas being blasted out of a compact galaxy at speeds of up to two million miles per hour.

The galaxy in question is called SDSS J0905+57, and the gas being driven from the galaxy is traveling distances of tens of thousands of light-years due to the intense pressure exerted on it by the radiation of stars that are forming at the galaxy's center. This process, in particular, has a major impact on the evolution of the galaxy.

So how did the astronomers spot this galaxy in the first place? They used a radio telescope based in the French Alps. By detecting the molecule carbon monoxide, they were able to infer the amount of hydrogen gas present. Stars are being born from clouds of hydrogen so by removing this gas, the galaxy can rapidly shut down its star formation. In fact, there is enough gas in the outflowing material to form over a billion suns.

Previously, researchers didn't know whether stars alone could drive out the gas in this way. Instead, astronomers believed that energy associated with a growing central black hole was required. Yet these new findings reveal a bit more about how star growth is regulated in galaxies.

"This discovery highlights the serendipity of scientific research," said James Geach, one of the researchers, in a news release. "Originally we were simply trying to measure the amount of dense gas in SDSS J0905+57. What we found was something surprising-a large fraction of the gas is being blasted out of the galaxy by the concentration of stars forming at the galaxy's center. We are witnessing the aggressive termination of star formation, and the mechanism by which this is happening is an important new clue in our understanding of the evolution of galaxies."

The findings are published in the journal Nature.

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