sentence: Astronomers now think that when a galaxy has a quasar, the quasar changes the galaxy.
sentences_after: Gas and dust from the galaxy falls onto the quasar, and the bright quasar heats up gas in the galaxy. This stops new stars from forming in the galaxy, so many of the elliptical galaxies we see in the universe now may have once had a quasar in their centers.
concept_name: astronomer
headings: Quasar
categories: Galaxies