Daily Archives: November 20, 2008

galaxies, galaxy interactions, starbirth

Star Pump

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The Little Galaxy that Could

Galaxies make stars. That’s what they’ve done since, well, since just about forever–in the cosmic scheme of things. Colliding galaxies pump out stars in huge batches. The action of smashing together two galaxies usually compresses their clouds of gas together and when you compress enough hydrogen gas together, you get stars. In colliding galaxies you get massive starburst regions like the one in NGC 1569, seen here through several observations made by Hubble Space Telescope’s Wide-Field Planetary Camera 2 and the Advanced Camera for Surveys.

Starburst galaxy NGC 1569. Whats causing its starburst activity?
The core of the starburst galaxy NGC 1569. This region contains three giant star clusters grouped inside a huge central cavity hollowed out by winds from the formation of massive stars. Those stars are long gone, having exploded as supernovae. The outbursts from those explosions hurled a river of gas and dust that is sculpting the 3,700 light-year-long outflow structure at the lower right (in red). (Click to embiggen.)

Now, astronomers have long puzzled over a small, isolated nearby galaxy (about 11 million light-years away) because it is ablaze with starburst activity. There are millions of newly formed stellar babies here, and this galaxy is continuing to pump out newborns a hundred times faster than the starbirth regions in the Milky Way Galaxy. So, given the intense rate of starbirth, you’d think you’d there’d be a collision involved here.

But, no, this galaxy seems to be all by itself.

Or so astronomers thought.

When they reanalyzed the observational data, they found that it really lies about one and a half times farther away from us than they thought. And that makes a huge difference. It puts this galaxy in the middle of a group of ten other massive galaxies. Interactions between this group that may be the culprit in compressing the gases in NGC 1569 and pumping up its prodigious starbirth engines. That interaction also makes this one of the most active galaxies in our local neighborhood.