NGC 922 in 60 Seconds
Narrator (April Hobart, CXC): In this holiday season of home cooking and carefully-honed recipes, some astronomers are asking: what is the best mix of ingredients for stars to make the largest number of plump black holes? They are tackling this problem by studying the number of black holes in galaxies with different compositions. One of these galaxies is the ring galaxy NGC 922 that was formed by the collision between two galaxies. This collision triggered the formation of new stars in the shape of a ring. Some of these were massive stars that evolved and collapsed to form black holes. Seven of the sources seen in the Chandra image are thought to contain stellar-mass black holes that are at least ten times more massive than the sun, which places them in the upper range for this class of black hole. By comparing NGC 922 to galaxies with different mixtures of elements, astronomers hope to master the ideal recipe for what it takes to make these large black holes.