Red stars and big bulges: How black holes shape galaxies
Tuesday, April 22, 2014 - 05:30
in Astronomy & Space
(Phys.org) —The universe we can see is made up of billions of galaxies, each containing anywhere from hundreds of thousands to hundreds of billions of stars. Large numbers of galaxies are elliptical in shape, red and mostly made up of old stars. Another (more familiar) type is the spiral, where arms wind out in a blue thin disk from a central red bulge. On average stars in spiral galaxies tend to be much younger than those in ellipticals.