Hubble finds a new contender for galaxy distance record
26 January 2011
Astronomers
have pushed NASA's Hubble Space Telescope to its limits by finding what
is likely to be the most distant object ever seen in the universe. The
object's light traveled 13.2 billion years to reach Hubble, roughly 150
million years longer than the previous record holder. The age of the
universe is approximately 13.7 billion years.
The tiny, dim
object is a compact galaxy of blue stars that existed 480 million years
after the big bang. More than 100 such mini-galaxies would be needed to
make up our Milky Way. The new research offers surprising evidence that
the rate of star birth in the early universe grew dramatically,
increasing by about a factor of 10 from 480 million years to 650 million
years after the big bang.
The
farthest and one of the very earliest galaxies ever seen in the
universe appears as a faint red blob in this ultra-deep–field exposure
taken with NASA's Hubble Space Telescope. This is the deepest infrared
image taken of the universe. Based on the object's color, astronomers
believe it is 13.2 billion light-years away. (Credit: NASA, ESA, G.
Illingworth (University of California, Santa Cruz), R. Bouwens
(University of California, Santa Cruz, and Leiden University), and the
HUDF09 Team)
› Larger image
"NASA
continues to reach for new heights, and this latest Hubble discovery
will deepen our understanding of the universe and benefit generations to
come,” said NASA Administrator Charles Bolden, who was the pilot of the
space shuttle mission that carried Hubble to orbit. “We could only
dream when we launched Hubble more than 20 years ago that it would have
the ability to make these types of groundbreaking discoveries and
rewrite textbooks.”
Astronomers don't know exactly when the first
stars appeared in the universe, but every step farther from Earth takes
them deeper into the early formative years when stars and galaxies
began to emerge in the aftermath of the big bang.
"These
observations provide us with our best insights yet into the earlier
primeval! objects that have yet to be found," said Rychard Bouwens of
the University of Leiden in the Netherlands. Bouwens and Illingworth
report the discovery in the Jan. 27 issue of the British science journal
Nature.
This observation was made with the Wide Field Camera 3
starting just a few months after it was installed in the observatory in
May 2009, during the last NASA space shuttle servicing mission to
Hubble. After more than a year of detailed observations and analysis,
the object was positively identified in the camera's Hubble Ultra Deep
Field-Infrared data taken in the late summers of 2009 and 2010.
The
object appears as a faint dot of starlight in the Hubble exposures. It
is too young and too small to have the familiar spiral shape that is
characteristic of galaxies in the local universe. Although its
individual stars can't be resolved by Hubble, the evidence suggests this
is a compact galaxy of hot stars formed more than 100-to-200 million
years earlier from gas trapped in a pocket of dark matter.
| This
video is a zoom into the Hubble Space Telescope infrared Ultra Deep
Field, first taken in 2009. It is a very small patch of sky in the
southern constellation Fornax. The zoom centers on the farthest
identified object in the field. The object, possibly a galaxy, looks red
because its light has been stretched by the expansion of the universe.
Credit: NASA/ESA/G. Bacon, STScI |
"We're
peering into an era where big changes are afoot," said Garth
Illingworth of the University of California at Santa Cruz. "The rapid
rate at which the star birth is changing tells us if we go a little
further back in time we're going to see even more dramatic changes,
closer to when the first galaxies were just starting to form."
The
proto-galaxy is only visible at the farthest infrared wavelengths
observable by Hubble. Observations of earlier times, when the first
stars and galaxies were forming, will require Hubble’s successor, the
James Webb Space Telescope (JWST).
The hypothesized hierarchical
growth of galaxies -- from stellar clumps to majestic spirals and
ellipticals -- didn't become evident until the Hubble deep field
exposures. The first 500 million years of the universe's existence, from
a z of 1000 to 10, is the missing chapter in the hierarchical growth of
galaxies. It's not clear how the universe assembled structure out of a
darkening, cooling fireball of the big bang. As with a developing
embryo, astronomers know there must have been an early period of rapid
changes that would set the initial conditions to make the universe of
galaxies what it is today.
"After 20 years of opening our eyes to
the universe around us, Hubble continues to awe and surprise
astronomers," said Jon Morse, NASA's Astrophysics Division director at
the agency's headquarters in Washington. "It now offers a tantalizing
look at the very edge of the known universe -- a frontier NASA strives
to explore."
Hubble is a project of international cooperation
between NASA and the European Space Agency. NASA's Goddard Space Flight
Center in Greenbelt, Md., manages the telescope. The Space Telescope
Science Institute (STScI) conducts Hubble science operations. STScI is
operated for NASA by the Association of Universities for Research in
Astronomy, Inc., in Washington.
요약: 우주의 나이가 137억 년인데 132억 광년 떨어진 별을 발견했다
빅뱅이 일어난 지 약 5억년밖에 안된 별의 최초 생성시기가 망원경에 잡힘
디아3
