NASA Telescopes Help Discover Surprisingly Young Galaxy

WASHINGTON -- Astronomers have uncovered one of the youngest galaxies
in the distant universe, with stars that formed 13.5 billion years
ago, a mere 200 million years after the big bang. The finding
addresses questions about when the first galaxies arose, and how the
early universe evolved.

NASA's Hubble Space Telescope was the first to spot the newfound
galaxy. Detailed observations from the W.M. Keck Observatory on Mauna
Kea in Hawaii revealed the observed light dates to when the universe
was only 950 million years old; the universe formed about 13.7 billion years ago.

Infrared data from both Hubble and NASA's Spitzer Space Telescope
revealed the galaxy's stars are quite mature, having formed when the
universe was just a toddler at 200 million years old.

"This challenges theories of how soon galaxies formed in the first
years of the universe," said Johan Richard of the Centre de Recherche
Astronomique de Lyon, Université Lyon 1 in France, lead author of a
new study accepted for publication in the Monthly Notices of the
Royal Astronomical Society. "It could even help solve the mystery of
how the hydrogen fog that filled the early universe was cleared."

This galaxy is not the most distant ever observed, but it is one of
the youngest to be observed with such clarity. Normally, galaxies
like this one are extremely faint and difficult to study, but, in
this case, nature has provided the astronomers with a cosmic
magnifying glass. The galaxy's image is being magnified by the
gravity of a massive cluster of galaxies parked in front of it,
making it appear 11 times brighter. This phenomenon is called
gravitational lensing.

"Without this big lens in space, we could not study galaxies this
faint with currently available observing facilities," said co-author
Eiichi Egami of the University of Arizona in Tucson. "Thanks to
nature, we have this great opportunity to see our universe as it was
eons ago."

The findings may help explain how the early universe became
"reionized." At some point in our universe's early history, it
transitioned from the so-called dark ages to a period of light, as
the first stars and galaxies began to ignite. This starlight ionized
neutral hydrogen atoms floating around in space, giving them a
charge. Ultraviolet light could then travel unimpeded through what
had been an obscuring fog.

The discovery of a galaxy possessing stars that formed only 200
million years after the big bang helps astronomers probe this cosmic
reionization epoch. When this galaxy was developing, its hot, young
stars would have ionized vast amounts of the neutral hydrogen gas in
intergalactic space. A population of similar galaxies probably also
contributed to this reionization, but they are too faint to see
without the magnifying effects of gravitational lensing.

NASA's James Webb Space Telescope (JWST), scheduled to launch later
this decade, will be able to see these faint galaxies lacking
magnification. A successor to Hubble and Spitzer, JWST will see
infrared light from the missing population of early galaxies. As a
result, the mission will reveal some of our universe's best-kept secrets.

"Seeing a galaxy as it appeared near the beginning of the universe is
an awe-inspiring feat enabled by innovative technology and the
fortuitous effect of gravitational lensing," said Jon Morse, NASA's
Astrophysics Division director at the agency's headquarters in Washington.

"Observations like this open a window across space and time, but more
importantly, they inspire future work to one day peer at the stars
that lit up the universe following the big bang."

For more information about Spitzer and Hubble, visit:




Source: NASA

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