Time's Dawn
The farthest galaxy around
An artist's impression shows the young galaxy UDFy-38135539 gathering up the hydrogen and helium gas surrounding it and forming many young stars
Our Universe is decorated with the most ancient celestial marvels. One predates the other. Recently, European astronomers, with the aid of European Southern Observatory's (ESO) Very Large Telescope (VLT), have discovered something that is the remotest and as such the most ancient of cosmic wonders. This distinguished and most senior citizen of our Universe is called UDFy-38135539, which is located in the constellation of Fornax. Back in 2009, this galaxy's image was first captured in the Hubble Ultra Deep Field (UDF) by the Hubble telescope's Wide Field Camera 3. And since then the careful analysis of the very faint glow of this galaxy revealed that this galaxy, which contains roughly a billion stars, was formed within the 600 million years of the very Big Bang that started the journey of this very cosmos about 13.7 billion years ago. And astonishingly, it has taken 13.1 billion years for lights from that galaxy to reach Earth! According to Dr. Matt Lehnert of Observatoire de Paris who is the lead author of the paper, "Using the ESO Very Large Telescope we have confirmed that a galaxy spotted earlier using Hubble is the most remote object identified so far in the Universe". It is important to note that astronomers determine the cosmic distances by measuring the redshift which is an estimate of how much an object's emitted light has been stretched in wavelength during it course of journey across our expanding Universe. To put it simply, redshift allows astronomers to calculate any celestial object's age. And it was found that UDFy-38135539 (UDFy from now on, for the sake of easy reading) has a redshift of 8.55. This means that the redshift of UDFy tops the previous record holder of the oldest object in the Universe. And that was a short-lived gamma-ray burst and called GRB 090423, which had a redshift of about 8.2 and was, formed about 630 millions after the Big Bang. Published in the 21st issue of the journal, Nature, scientists explain that this is quite an exciting discovery because, UDFy, with it's 8.55 redshift, is the first ever galaxy known to man which have lived fully within the seeming era of re-ionization of the Universe which lasted for about 150 million to 800 million years after the great Big Bang. At that point in time, intense ultraviolet radiation from the first stars was clearing the dense fog of neutral hydrogen that filled the cosmos by splitting its hydrogen atoms into electrons and protons. And it is this process that is known as re-ionization, which is in fact transformed the cosmos from an obscure haze to the typically empty space we know it today. One of the factors of this discovery that puzzles astronomers is that, the glow from UDFy seems like not strong enough to tunnel its way through the thick hydrogen fog on its own. And scientists believe that there must be other fainter and less massive galaxies in its vicinity, which assisted greatly to clear out the neighborhood of UDFy. And such fainter galaxies are yet to be identified by the Hubble UDF.
For all latest news, follow The Daily Star's Google News channel.
Comments