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Thursday, April 24, 2014         

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Scientists use Mauna Kea scope to spot most distant galaxy yet

By Ralph K.M. Haurwitz

Austin American-Statesman

POSTED:

courtesy HUBBLE HERITAGE TEAMAn artist's rendition shows the galaxy z8-GND-5296, discovered using the Hubble Space Telescope and further studied by the Keck Observatory.

AUSTIN, Texas » Using the Hubble Space Telescope and an observatory in Hawaii, researchers at the University of Texas, Texas A&M University and other institutions have detected the most distant galaxy discovered so far.

Their findings, published Thursday in the journal Nature, document a place in the far reaches of the universe known by a name only scientists could love: z8-GND-5296. Unlike the Milky Way, which creates one or two sunlike stars every year or so, the newly discovered one forms about 300 such stars a year.

"We were thrilled to see this galaxy," said UT astronomer Steven Finkelstein, who led the research team.

When scientists look at distant galaxies, they see them as they appeared in the past because of the time it takes for a galaxy's light to reach Earth. The newly discovered galaxy was seen by the researchers as it appeared 13 billion years ago.

"Because of its distance, we get a glimpse of conditions when the universe was only about 700 million years old -- only 5 percent of its current age of 13.8 billion years," A&M astrophysicist Casey Papovich said.

Taking into account the continuous expansion of the universe, the researchers estimate that the galaxy is now about 30 billion light-years away; a light-year is the distance light travels in a year, or nearly 6 trillion miles.

The team chose this galaxy and dozens of others for research from about 100,000 galaxies discovered in a Hubble survey.

They focused on how much the galaxies' light wavelengths have shifted toward the red end of the color spectrum during their travels to Earth, a phenomenon called "redshift." The researchers probed the heavens April 17 and 18 -- two crisp, clear nights -- from the control room of the W.M. Keck Observatory atop Hawaii's dormant Mauna Kea volcano. The observatory houses two of the largest earthbound telescopes.

"This is a very skeptical group, and everyone was pretty convinced about this galaxy from their first look, though it wasn't until a couple weeks later that we did enough testing to believe it," Finkelstein said. "We have to do a process called data reduction, where we remove instrumental effects, stack together all of the data we took and calibrate the data." There might well be more distant galaxies, but z8-GND-5296 turned out to be the most distant ever confirmed, with a redshift of 7.51 -- meaning it was created about 13 billion years ago. The galaxy with the previous record for distance, with a redshift of 7.2, also has a high rate of star formation and is situated in the same part of the sky as the new distance-record holder.

"So we're learning something about the distant universe," Finkelstein said. "There are way more regions of very high star formation than we previously thought. There must be a decent number of them if we happen to find two in the same area of the sky."

UT and A&M are also collaborating in other studies of the cosmos. For example, they and other institutions are working on a project at UT's McDonald Observatory in West Texas that will attempt to learn about dark energy, a mysterious force thought to permeate space and drive the expansion of the universe.






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