Thursday, 5 April 2018

Beyond the Farthest Star

Astronomer have announced the detection of the farthest individual star so far observed. The star, a blue supergiant (so very luminous indeed), lies over nine billion light years away. This means that the light from the star detected was emitted around 4.5 billion years after the Big Bang, according to the current model.

Now, this might sound like the star is pretty young compared to the Universe itself, and indeed, galaxies have been observed which are estimated to be almost 13 billion light years away, so we are seeing as they formed only hundreds of millions of years after Event One. However, this is the farthest, oldest star that has been detected individually. As with the farthest galaxies, the star has been visualised using gravitational lensing - space-time has been severely curved by high mass objects passing between us and the location of the star (in this case, a galactic cluster, with the lensing compounded by an unknown other mass). This magnifies the star making it bright enough to be detected at huge distances. However, the star is now long dead - blue supergiants have an estimated lifespan of a mere ten million years, a thousand times less than our own sun.

This is an amazing discovery, a combination of great luck and ingenious technique. One thing that does puzzle me is the name, though. Like most astronomical objects, the star has a catalogue designation (MACS J1149+2223 Lensed Star-1, the MACS prefix standing for MAssive Cluster Survey) but has been nicknamed Icarus. It's a nice name, but Icarus is famous for flying too close to the sun. It's a strange choice for the star that is farthest from the sun.

Link for more info

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