Astronomers find rare spiral galaxy
2012-07-19 07:29
Paris - Astronomers said they had stumbled upon an astonishing spiral galaxy that was born nearly 11 billion years ago, a finding that could spur a rethink of how galaxies formed after the Big Bang.
Dubbed BX442, the ancient star cluster was discovered in a survey of 300 distant galaxies carried out by the powerful Hubble Space Telescope and the Keck Observatory in Hawaii.
"Lo and behold, with no warning, BX442 and its spiral galaxy just popped out of the image. We couldn't believe it!" said Alice Shapley of the University of California Los Angeles, reported in Nature journal.
"We were not expecting such a beautiful pattern, given that the vast majority of star-forming galaxies in the early universe look so irregular and lumpy."
BX442 is the first "grand design" spiral galaxy to be observed so early in history.
Located 10.7 billion light years away, it was created some three billion years after the universe was born in a superheated flash.
A "grand design" galaxy formation is one with well-defined arms spiralling out in opposite directions from a central cluster of stars in a pattern resembling an "S", like our Milky Way.
Other galaxies observed this far back in time have irregular, clumpy structures, with conditions too hot to allow them to settle down into a spiral.
"The vast majority of old galaxies look like train wrecks," said Shapley.
"The discovery of BX442 tells us that a spiral pattern can form in the early universe, which we did not know," and represents a link between early, turbulent galaxies and the rotating spiral kind we find today.
Studying BX442 may help astronomers understand how spiral galaxies form.
