which consist primarily of hydrogen, are also rich in iron. Since heavy elements like iron are produced only deep inside stars and are ejected into interstellar space by events like supernova explosions, astronomers believe the gas must have come from regions surround- ing stars. Presumably, stars exploded, ejecting iron into space; as the parent galaxies moved through the clusterΓÇÖs center, the iron-enriched gas was extracted and deposited in intergalactic space.
