Modern galaxies like our own Milky Way became giants by
swallowing their smaller neighbors and absorbing their billions
of stars. But how did the earliest galaxies grow when there
weren't nearly as many stars to swallow? A new study, reported
online today in Nature, suggests that they swallowed the
ingredients for stars instead. A team studying three galaxies
that formed over 11 billion years ago observed them all sucking
up cold, primordial hydrogen and helium gas from intergalactic
space and churning out new stars in their central, star-making
regions. Once the gas disappears, the galaxies either acquire
new stars via mergers or in the aftermath of supernova
explosions, which seed the heavens with heavier elements. See
more ScienceShots.