Black Holes May Shut Down Starbirth in Hearts of Galaxies
(From the November/December 2006 issue of StarDate magazine)
The supermassive black holes at the centers of galaxies are already known as star destroyers, because they pull apart and consume any stars that pass too close. But a recent study suggests that the black holes could destroy stars even before they have a chance to form.
Radiation and jets from a supermassive black hole disrupt starbirth at the center of an elliptical galaxy in this artist's concept. [NASA/JPL]
Using observations from the orbiting Galaxy Evolution Explorer (GALEX), a team led by Sukyoung Yi of Yonsei University in South Korea found that supermassive black holes may shut down starbirth in some galaxies.
These black holes are millions or billions of times as massive as the Sun. They are so dense that their gravitational pull prevents even light from escaping. They pull in the stars and gas around them, surrounding themselves with superhot spirals of gas known as accretion disks.
GALEX surveyed the ultraviolet glow of more than 800 nearby elliptical galaxies. Ultraviolet energy is produced by especially hot objects like massive young stars. The observations showed that more massive galaxies, which contain more massive central black holes, have fewer young stars. Yi’s team suggests that the black holes shut down star formation by gobbling up all the available gas for new stars, by making the gas too hot to coalesce into stars, or by blowing away the gas through jets of radiation and atomic particles. — Damond Benningfield