Here in the Milky Way, new stars are formed at a rate of roughly 4 per year; that’s considered pretty normal for spiral galaxy like ours. But researchers have found a galaxy that’s absolutely bursting with new star formation. Instead of our leisurely 4 stars per year, this distant galaxy is generating more than 4,000 new stars a year.
The galaxy, known at GOODS 850-5, is located about 12 billion light-years from Earth. This means that astronomers are seeing the light coming from it at a point when the Universe was only 1.5 billion years old.
All of the star formation in this galaxy was obscured by thick layers of dust, emitted by all the stellar nurseries. This means they’re hidden by visible-light telescopes.
By using the Smithsonian Astrophysical Observatory’s Submillimeter Array (SMA) on Mauna Kea in Hawaii, the researchers were able to peer right through the obscuring dust to calculate the rate of star formation.
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The irony is that the dust from all that star formation was obscuring the, uh, star formation. Here’s Wei-Hao Wang, one of the astronomers who worked on the research:
“This evidence for prolific star formation is hidden by the dust from visible-light telescopes,” Wang explained. The dust, in turn, was formed from heavy elements that had to be built up in the cores of earlier stars. This indicates, Wang said, that significant numbers of stars already had formed, then spewed those heavy elements into interstellar space through supernova explosions and stellar winds.
This discovery has come as a bit of a surprise, since astronomers used to think that the most actively star forming galaxies would be smaller and less obscured. Now they’re starting to realize that it’s actually the big dusty galaxies that form the most stars. We just couldn’t see it.
For a galaxy to be experiencing this much star formation, it must have gone through many rounds of mergers with other galaxies. And this is also surprising, considering it’s only 1.5 billion years old in the image.
Original Source: NRAO News Release