Oldest galaxy: Hubble telescope detects farthest, oldest galaxy yet
Oldest galaxy: Astronomers using the Hubble telescope have detected a galaxy that formed just 500 million years after the Big Bang, making it the most distant and oldest galaxy discovered so far.
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Astronomers using the Hubble Space Telescope have peered further back in time than ever before, spotting a galaxy that formed less than 500 million years after the birth of our universe, making it the oldest and most distant ever seen.
The find, reported today (Jan. 26) in the journal Nature, should help astronomers better understand the early days of the universe, researchers said. In particular, the discovery should shed light on the evolution of early galaxies, which first formed just a few hundred million years after the Big Bang.
"In essence, the most important aspect of this is, it provides us with some sense of how fast galaxies are building up," lead author Rychard Bouwens, of the University of California, Santa Cruz (UCSC) and Leiden University in The Netherlands, told SPACE.com. "It provides a sort of measuring stick."
Peering backward through time
Bouwens and his colleagues analyzed observations made by NASA's Hubble Space Telescope. They looked at infrared data gathered by Hubble's Wide Field Camera 3, which was installed on the telescope in 2009. [Most Amazing Hubble Discoveries]
The researchers found evidence of a galaxy with a redshift of 10.3. "Redshift" is a measure of how much the expansion of space has stretched an object's light to longer (or redder) wavelengths. Light from objects moving away from us shifts to the red end of the spectrum as its wavelengths are stretched. The shift, known as the Doppler phenomenon, is experienced on Earth when sound waves from an ambulance change pitch when the ambulance moves toward you versus away from you.
Astronomers use redshift measurements to determine an object's distance, and by extension its age. The bigger the redshift, the greater the distance.
A redshift of 10.3 corresponds to a distance of about 13.2 billion light-years. That is, it's taken 13.2 billion years for the light from the newly discovered galaxy — which has been named UDFj-39546284 — to reach us.
That makes UDFj-39546284 the most distant known galaxy in the universe, beating out the old record-holder by about 100 million light-years.
Since the universe is roughly 13.7 billion years old, UDFj-39546284 was around nearly at the beginning — just 480 million years after the Big Bang, or when the universe was just 4 percent of its current age.
Officially, UDFj-39546284 remains a "galaxy candidate," requiring some more observations to confirm its existence and age with certainty. But after performing a number of tests, Bouwens and his team are confident that the galaxy is there, and that its redshift is around 10.3.
"Everything we found was completely consistent with it being a real source," Bouwens said. "It looks really good right now."
Understanding galaxy formation
In addition to studying UDFj-39546284, the researchers also looked at several galaxies that are slightly younger, dating to about 650 million years after the Big Bang. They saw dramatic differences between the older and younger galaxies, suggesting that the rate of star birth jumped by a factor of 10 in the intervening 170 million years.