Hubble Pushes Back The Clock

Analysis of far-infrared data collected during the Hubble Space Telescope’s Ultra Deep Field observations has turned up what scientists believe to be the earliest galaxy ever spotted, pointing the way for more discoveries with the planned James Webb Space Telescope.

According to a scientific paper on the discovery to be published in the journal Nature, the compact galaxy of blue stars — merely one one-hundredth the size of the Milky Way — existed only 480 million years after the Big Bang.

Light from the object — too distant to resolve the individual stars — traveled for 13.2 billion years to reach the orbiting observatory.

That breaks the old record for Hubble by 150 years, but that record is likely to be shattered if NASA can overcome cost overruns to launch the Webb telescope, which is designed to look back even deeper into the red-shifted early Universe.

“We’re peering into an era where big changes are afoot,” says Garth Illingworth of the University of California/Santa Cruz, who co-authored the Nature paper with Rychard Bouwens of the University of Leiden. “The rapid rate at which the star birth is changing tells us if we go a little farther back in time we’re going to see even more dramatic changes, closer to when the first galaxies were just starting to form.”

Based on the new data, Illingworth and Bouwens calculate that the rate of star birth over the period from 480 million years after the Big Bang to 650 million years increased by a factor of 10 — much faster than expected. Webb may be able to push back deeper into the roughly 13.7-billion-year mark accepted as the age of the Universe to help astronomers better understand when and how the first stars formed.

“These observations provide us with our best insights yet into the earlier primeval objects that have yet to be found,” Bouwens says.

The galaxy was found in the Ultra Deep Field, a long-exposure observation with the Wide Field Camera 3 installed on the Hubble in May 2009. Analysis of the data and confirmation of the galaxy’s age took about a year.