Clumps of new stars 'spotted' in a galaxy far, far away

A team of astronomers has pushed NASA's Hubble Space Telescope beyond its limits to spot the clumps of new stars in a distant galaxy.

By applying a new computational analysis to a galaxy magnified by a gravitational lens, astronomers have obtained images 10 times sharper than what Hubble could achieve on its own. The results show an edge-on disk galaxy studded with brilliant patches of newly formed stars.

"When we saw the reconstructed image we said, 'Wow, it looks like fireworks are going off everywhere'," said astronomer Jane Rigby of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

The galaxy in question is so far away that we see it as it appeared 11 billion years ago, only 2.7 billion years after the big bang. It is one of more than 70 strongly lensed galaxies studied by the Hubble Space Telescope, following up targets selected by the Sloan Giant Arcs Survey, which discovered hundreds of strongly lensed galaxies by searching Sloan Digital Sky Survey imaging data covering one-fourth of the sky.

The gravity of a giant cluster of galaxies between the target galaxy and Earth distorts the more distant galaxy's light, stretching it into an arc and also magnifying it almost 30 times. The team had to develop special computer code to remove the distortions caused by the gravitational lens, and reveal the disk galaxy as it would normally appear.

The resulting reconstructed image revealed two dozen clumps of newborn stars, each spanning about 200 to 300 light-years. This contradicted theories suggesting that star-forming regions in the distant, early universe were much larger, 3,000 light-years or more in size.

"There are star-forming knots as far down in size as we can see," said University of Michigan's Traci Johnson, lead author of two of the three papers describing the research.

Without the magnification boost of the gravitational lens, Johnson added, the disk galaxy would appear perfectly smooth and unremarkable to Hubble. This would give astronomers a very different picture of where stars are forming.

The study is published in The Astrophysical Journal.