Oldest spiral galaxy in universe discovered
Compiled from news reports
Astronomers have discovered the universe's most ancient spiral galaxy yet, a cosmic structure that dates back roughly 10.7 billion years, a new study reveals.
The galactic find, discovered by researchers using NASA's Hubble Space Telescope, comes as something of a surprise. Other galaxies from such early epochs are clumpy and irregular, not strikingly symmetrical like the newfound spiral, which broadly resembles our own Milky Way.
"The fact that this galaxy exists is astounding," study lead author David Law, of the University of Toronto, said in a statement. "Current wisdom holds that such ‘grand-design’ spiral galaxies simply didn’t exist at such an early time in the history of the universe."
A team reporting in Nature says the galaxy BX442 got the gravitational "kick" it needed to form a spiral from a smaller "dwarf galaxy" orbiting it.
They first spotted BX442 as the one and only spiral-looking object in a survey of 300 galaxies carried out by the Hubble space telescope, when they were shocked to see what looked to be a spiral galaxy.
"What we've learned when we look at galaxies at that epoch is that they're very dynamically hot," explained Law.
"Even though we see some discs existing at that time, they're very thick and puffy, whereas the Milky Way has an... amount of random motion only about a tenth or so the amount of ordered rotation, giving rise to a very thin disc," he told BBC News.
To get a closer look at BX442, the team went on to use the OH-Suppressing Infrared Integral Field Spectrograph at the Keck observatory in Hawaii -- which can subtract the effect of all the water that lies between the Earth and galaxies at such astronomical distances.