Hubble spies fledgling galaxies as astronomy goes back in time

Dec 13, 2012
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Hubble spies fledgling galaxies as astronomy goes back in time

NASA has released images of primitive galaxies formed more than 13 billion years ago, using the Hubble Space Telescope to share the deepest images of our universe to-date. The views of the Ultra Deep Field (UDF12) area of space revealed seven fledgling galaxies in their state back when the universe was less than 4-percent of its current age, just 450 million years after the big bang.

The shots were taken between August and September, by a team of astronomers at the California Institute of Technology in Pasadena. Hubble used near-infrared optics to in effect peer back in time to the earlier days of the universe, with deeper exposures and extra filters used to achieve the images.

The upshot is a two-fold achievement in the telescope's history, first in the length of exposures it can take, and second in how color filters can be used to "more precisely measure galaxy distances." In fact, four filters were used, with close near-infrared wavelengths.

"We added one filter, and undertook much deeper exposures in some filters than in earlier work," James Dunlop of the Institute for Astronomy at the University of Edinburgh in Scotland said of the project, "in order to convincingly reject the possibility that some of our galaxies might be foreground objects."

As for what the images tell us of the universe's origins, they lend weight to theories that galaxies assemble continuously over time, and that they "may have provided enough radiation to reheat, or re-ionize, the universe a few hundred million years after the theorized big bang" NASA says. The so-called "re-ionization" process is said to have occurred 200m to 1bn years after the big bang.

"Our data confirm re-ionization was a gradual process, occurring over several hundred million years, with galaxies slowly building up their stars and chemical elements," Brant Robertson of the University of Arizona in Tucson said of the findings. "There wasn’t a single dramatic moment when galaxies formed. It was a gradual process."

Meanwhile, the results will also help shape the upcoming James Webb Space Telescope, which will follow on from Hubble's exploration. The team plans to host a webinar to answer questions and explain their findings on Friday this week.


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