Astronomers using the Hubble Space Telescope to peer some 11 billion light-years into space and as many years back in time have seen something they didn't expect: fully formed galaxies when the universe was still quite young.
Galaxies come in three broad categories — spirals, such as our own Milky Way and neighboring Andromeda; ellipticals; and lenticular galaxies that look like hybrids of the other two.
This categorization is known as the Hubble Sequence, and scientists have long wondered how long after the Big Bang it took for these islands of stars to form and take their recognizable forms.
BoMee Lee, of the University of Maryland, who is the lead author in the new study, has concluded that the familiar spirals, ellipticals and lenticulars existed at least as far back as 11.5 billion years ago, not long (on a cosmological scale, anyway) after the Big Bang, 13.8 billion years ago.
"The Hubble Sequence underpins a lot of what we know about how galaxies form and evolve; finding it to be in place this far back is a significant discovery," Lee says.
"This is the only comprehensive study to date of the visual appearance of the large, massive galaxies that existed so far back in time," the study's co-author, Arjen van der Wel, said in a statement. "The galaxies look remarkably mature, which is not predicted by galaxy formation models to be the case that early on in the history of the universe."
So, what do they actually look like? The researchers say they "appear to be split between blue star-forming galaxies with a complex structure — including discs, bulges and messy clumps — and massive red galaxies that are no longer forming stars."
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