Hubble Unmasks Ghost Galaxies
Tuesday, July 10, 2012 - 13:01
in Astronomy & Space
Astronomers have puzzled over why some puny, extremely faint dwarf galaxies spotted in our Milky Way galaxy's back yard contain so few stars. Hubble telescope views of Leo IV and two other small-fry galaxies in a recent study reveal that their stars share the same birth date. The galaxies all started forming stars more than 13 billion years ago -- and then abruptly stopped -- all in the first billion years after the universe was born in the big bang. Because the stars in these galaxies are so ancient and share the same age, astronomers suggest that a global event, such as reionization, shut down star formation in them.