Astronomers have discovered a star, in our own galaxy, which appears to be older than the present accepted age of the universe. Odd? In actual fact, it is, of course, impossible, unless our ideas of how the universe formed are totally wrong. So what have we got wrong: the age of the star, or the age of the universe? 

   Well it’s not quite as simple as that. There is an error margin for the estimate of the age of the star, and the lower end of that margin puts the star just within the estimated edge for the universe. The mysterious ‘Methuselah Star’ appears to be between 14 and 15 billion years old, while the universe itself is thought to have come into existence 13.7 billion years ago. But it’s still a major mystery how a star can be that old. And the chances of one of the earliest stars in the history of the universe just happening to be so close to the Sun at this time are also rather remote. At magnitude 7.2, it’s easily visible even in binoculars, in Libra. See below for its position. 

    And even after using new information about the star’s distance from us, its brightness and its structure, scientists are unable to place an estimate of its age much below 14.5 billion years – still older than the universe. 

   Fortunately for the team from Pennsylvania State University and the Space Telescope Science Institute in Baltimore, there appears to be a margin of error of about 800 million years, or so – enough to just barely place the star below the age of everything else. 

   Known as HD 140283, or TYC 5601-694-1, the star is the oldest object currently known to astronomers. It was first discovered a century ago, moving more than 800,000 mph relative to the Sun. It is on a long and looping orbit around the galaxy, and is only briefly passing through our neighbourhood. 

    In the study published in Astrophysical Journal Letters, astronomers said the star was born in a ‘dwarf galaxy’ which was swallowed by the Milky Way more than 12 billion years ago. Using new measurements the team was able to refine its estimate of the star’s position, and learn more about its structure. 

   The study suggests that further research might bring the age of the star down even further. See:

http://www.huffingtonpost.co.uk/2013/03/08/astronomers-find-ancient-star-methuselah_n_2834999.html

 – from the newssheet of the Irish Astronomical Association, written by Terry Moseley