Ancient galaxy is more than 13 bn light yrs away

Astronomers today said a galaxy born in childhood of Universe lies at least 13 bn light years away.

Paris: European astronomers today said a galaxy born in the childhood of the Universe lies at least 13 billion light years away, making it the remotest object ever observed.

Light from the galaxy UDFy-38135539 that reaches Earth today was emitted when the cosmos was only 600 million years old and mired in a primordial "fog" of hydrogen atoms, they said.

It has taken 13.1 billion years, travelling at 300,000 kilometres per second, for this smudge of infant light to arrive.

The study, appearing in the British journal Nature, used a giant European telescope in Chile`s Atacama desert to measure the galaxy`s so-called redshift.

The more distant a light source is, the longer its wavelength stretches. In other words, a light that appears to be receding from the observer shifts more towards the red part of the optical spectrum.

In this case, the galaxy`s redshift was 8.6, making it the most distant object ever observed by spectroscopy.

The previous documented record, in 2009, was a redshift of 8.2 caused by a gamma-ray burst of a super-massive star. An object at a redshift of 10 was once reported but has never been confirmed.

"Measuring the redshift of the most distant galaxy so far is very exciting in itself, but the astrophysical implications of this detection are even more important," said Nicole Nesvadba of France`s Institut d`Astrophysique Spatiale.

"This is the first time we know for sure that we are looking at one of the galaxies that cleared out the fog which had filled the very early Universe."

Under the "Big Bang" theory, the Universe originated in a superheated-flash around 13.7 billion years ago and started to expand.

After the cosmos had cooled a little, electrons and protons teamed up to form hydrogen, which for hundreds of millions of years filled the Universe.

During this epoch, known as the Universe`s "Dark Ages," there were no stars. It was followed by a period known as reionisation, in which the first stars formed and their intense ultra-violet radiation managed to pierce the hydrogen fog.

PTI

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