telescope's latest find pushes back clock on galaxy formation
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[March 04, 2016]
By Irene Klotz
CAPE CANAVERAL, Fla. (Reuters) -
Astronomers said on Thursday they had discovered a galaxy that formed
just 400 million years after the Big Bang explosion, the most distant
galaxy found to date.
Located a record 13.4 billion light-years from Earth in the
direction of the constellation Ursa Major, the galaxy, named GN-z11,
was first spotted two years ago in a Hubble Space Telescope deep-sky
visible light survey.
At the time, astronomers knew they were seeing something very far
away, possibly as distant as 13.2 billion light-years from Earth.
Follow-up observations with an instrument on Hubble that splits
light into its component wavelengths revealed that GN-z11 was
farther away than initially believed, setting back the
galaxy-formation clock by another 200 million years.
Being able to use Hubble to peg the galaxy's distance was a
surprise, said astronomers who will publish their research in next
week's issue of The Astrophysical Journal.
"We've taken a major step back in time, beyond what we'd ever
expected to be able to do with Hubble," Yale University astronomer
Pascal Oesch said in a statement.
The key to the discovery was precisely measuring the shift of the
galaxy's light into longer, redder wavelengths, which directly
corresponds to how far the photons had traveled before reaching
The phenomenon is similar to the sound of a train whistle shifting
pitch as it recedes into the distance.
Though small by modern galaxy standards, GN-z11 is huge considering
it formed at a time when the universe was only 3 percent of its
present age, said astronomer Garth Illingworth with the University
of California, Santa Cruz.
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"We're seeing this galaxy in its infancy," Illingworth said. "It's
amazing that a galaxy so massive existed only 200 million to 300
million years after the very first stars started to form."
GN-z11 contains about 1 billion times the mass of the sun. The
galaxy is about 25 times smaller than the Milky Way, though it is
pumping out new stars 20 times faster than the present Milky Way.
Astronomers said they expected the new distance record to stand
until Hubble's successor, the James Webb Space Telescope, is
launched in 2018.
(Reporting by Irene Klotz; Editing by Ian Simpson and Sandra Maler)
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