The Milky Way's Deadly Inner Zone

By Jessa Forte Netting|Sunday, January 02, 2005

This tortured cloud is what’s left of a supernova that was seen in 1604. Epidemics of such stellar detonations may repeatedly wipe the center of our galaxy free of life.

Courtesy of NASA/ESA/R. Sankrit and W. Blair (JHU)

From Earth, you might think the Milky Way is peaceful and rather boring. Other galaxies collide, explode, or rip themselves apart, while ours seems to rotate in an orderly, unchanging spiral. But Antony Stark of the Harvard-Smithsonian Center for Astrophysics suggests we are simply enjoying a calm between galactic storms. In the next 10 million years a cataclysm at the center of the Milky Way will destroy old stars, birth new ones, and sterilize a swath of space thousands of light-years wide.

The cause of this impending conflagration, according to Stark’s analysis, is the massive black hole at the heart of the Milky Way, which is steadily pulling a tide of stars and gas inward. A ring of galactic flotsam is building up there in an elongated oval, like the rings that encircle Saturn. “As more and more material piles on, it will coagulate in two lumps, as if Saturn’s rings lumped up to form a moon,” Stark says. When the accumulation reaches a critical point, all the material will pour inward. The central black hole, smaller than Earth’s orbit around the sun, will be unable to swallow all that mass, equivalent to 30 million suns. The overflow of compressed gas will spawn a starburst—a swarm of giant stars that rapidly burn out and explode in a series of supernova explosions, bathing the region in hard radiation.

That radiation would exterminate any organisms nearby, supporting the idea that entire galaxies have enormous danger zones where life cannot survive. But at our distance, 25,000 light-years from the center, we could safely sit back and enjoy the show—secure in the knowledge that our galaxy is definitely not dull. “Astronomers used to think there was something special about starburst galaxies,” says Stark. “This shows that even normal galaxies like the Milky Way are sarbursts some of the time.”

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