Supernova Factories
 An artist's concept shows a star cluster filled with the glow of red supergiant stars. At left, one of the stars has already exploded as a supernova. Red supergiants are the largest and most massive stars in the galaxy, and most will die in titanic explosions. Astronomers have discovered two clusters that, combined, contain about 40 red supergiants -- about 20 percent of all the known red supergiants in the galaxy. [NASA/ESA/A. Schaller (STScI)]
To the northeast of Antares, though, in the nearby constellation Scutum, are two star clusters that together contain about 40 red supergiants. That's about one-fifth of the known red supergiants in the entire Milky Way galaxy.
The clusters are only a few hundred light-years apart, which may be a clue to why they contain so many supergiants. The clusters are near the edge of a fat "bar" of stars in the heart of the Milky Way. As the bar rotates, its gravity may squeeze big clouds of gas and dust outside the bar. The clouds collapse to form clusters of thousands of stars -- including the supergiants.
Both clusters are about 20,000 light-years from Earth. They're hidden behind vast clouds of dust, so they're not visible to the human eye. Astronomers discovered them through their infrared energy, which shines through the dust.
Red supergiants live no more than 10 million to 20 million years, then explode as supernovae. So like Antares, the stars in these clusters are doomed to blast themselves to bits.
Script by Damond Benningfield, Copyright 2008
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