Monday, November 30, 2015         

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Phenomenon of light puts old galaxy in sharp focus

By Star-Advertiser staff


WAIMEA, Hawaii » Astronomers using the 10-meter Keck II Telescope on Mauna Kea have discerned intriguing new information about an early galaxy using an accident of nature called a gravitational lens.

The galaxy, called Sp1149, is 9.3 billion light-years away and would look tiny and indistinct even to the powerful Keck without the lensing effect.

Gravitational lenses happen when colossally massive clusters of thousands of galaxies bend and magnify the light of more distant objects behind them in a way similar to a glass lens.

In the case of Sp1149, however, the image appears relatively clear because the light from the galaxy was bent by the same amount in every direction around the gravitational mass.

That's like a baseball pitcher throwing simultaneous curve balls and having them arrive in the catcher's mitt at the same time via different routes.

"We're lucky that it's not being terribly distorted," said astronomer Lisa Kewley of the University of Hawaii at Manoa. "Something so far away that's not lensed would look like a blurred dot."

The clarity allowed Kewley, along with UH astronomer Tiantian Yuan and colleagues, to study the distribution of chemical elements in a galaxy when the universe was only a third of its current age.

The distribution of oxygen suggests that stars in the cores of galaxies form first, followed later by the disk and arms. That supports what is called the inside-out model of galactic evolution, Kewley said.

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