August 19, 2017

20.02.11: A Snapshot of a Primordial Galaxy.

When it comes to the Hubble Space Telescope, the hits just keep on a’ comin’… earlier this year, researchers pushed the refurbished telescope to its limits, revealing what may prove to be most distant galaxy (or indeed object) yet seen. At 13.2 light years distant, the smudge pictured above would have been from a time when the universe was only about 500 million years old.

For comparison, the current age of our universe stands at about 13.7 billion years and counting. The images are courtesy of Hubble’s new Wide Field Planetary Camera (WFPC3) installed by the final Atlantis servicing mission STS-125. The image is a slice of what is known as the Hubble Ultra Deep Field, an 87 hour exposure spanning two four day spans in 2009 and 2010. The image covers a patch about 1/10th the apparent size of a Full Moon in the constellation Cetus.

…And just how do we know said smudge is so distant? For cosmological distances, astronomers measure what’s known as redshift, or the factor that tell tale spectral lines are stretched and shifted towards the infrared as the light traverses our expanding universe. The higher the shift, the more distant an object. At 10.3, the redshift of the object above represents the limits of Hubble, and is a feat that astronomers will have to wait for the launch of the James Webb Space Telescope in 2014 to surpass.

This early era of the universe is a fascinating one. This was only a scant 100,000+ years after the cosmic microwave background decoupled from a cooling young universe, allowing the first hydrogen atoms to form and radiation to shine freely through the universe. From there, the very first stars began nuclear fusion and star formation built up by a factor of ten over less than a span equal to 1% of the current age of the universe… will we have a image dating back to the time of the CMB in the next decade? It’s quite possible!

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