Astronomers using ESO’s Very Large Telescope (VLT) have measured the distance to the most remote galaxy so far, UDFy-38135539, existing when the Universe was only about 600 million years old (a redshift of 8.6). Image: M. Alvarez, R. Kaehler, and T. Abel
(PhysOrg.com) — A European team of astronomers using ESO’s Very Large Telescope (VLT) has measured the distance to the most remote galaxy so far. By carefully analysing the very faint glow of the galaxy they have found that they are seeing it when the Universe was only about 600 million years old (a redshift of 8.6). These are the first confirmed observations of a galaxy whose light is clearing the opaque hydrogen fog that filled the cosmos at this early time. It has taken 13.1 billion years, travelling at 300,000 kilometres (186,000 miles) per second, for this smudge of infant light to arrive
The distance to faraway galaxies is measured by noting how rapidly they are moving away from our own. Because the universe is expanding at an ever-increasing pace, all widely dispersed galaxies retreat from each other at greater speeds the farther apart they are.
Scientists measure all this by noting a galaxy’s redshift, the extent to which the wavelengths of its light have been stretched toward the red end of the spectrum during its long travels across the cosmos.
The previous record holder, a Sloan galaxy, is at redshift 6.4.
The newfound galaxy has a redshift of at least 6.6, based on the Hubble imaging, and may be near 7.0 according to a less firm analysis of the Keck observations.
The universe is now about 13.7 billion years old.
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