Sutherland – Astronomers have discovered a super rare new star – so rare that out of the billions of stars in the universe, there are only 16 of them recorded.
And one of the astronomers that found it is Alexei Kniazev, from the SA Astronomical Observatory (SAAO) in Cape Town, who worked with two Moscow State University astronomers, Vasilli Gvaramadze and Leonid Berdnikov.
The star is known as a “luminous blue variable”, which are particularly interesting to astronomers because they are extremely old.
Despite their age and rarity, they have really dull names: the newest is called simply WS1.
The SAAO said yesterday because the luminous blues were so old, they could die soon in a supernova explosion, one of the most powerful explosions in the universe.
The observatory said just like humans, stars did not live forever, and once their fuel had run out they stopped shining and died.
However, no one knew exactly when these supernova deaths would occur, so astronomers kept an eye on the luminous blue variable stars because they were at a stage in the evolution of massive stars where their death was imminent.
The stars had masses of between 20 to 25 times that of our Sun and the luminous blue variable stage occurred just before the stars died in “a spectacular supernova explosion”.
Luminous blue variables were much hotter and so were more luminous than our Sun.
They were some of the most luminous stars known, with a brightness ranging from 250 000 to 1 million times brighter than our Sun.
As a consequence of their high mass they evolved very quickly and had, astronomically speaking, short lifetimes of a few million years.
The phase when they were luminous blues – regarded as their “retirement” phase – was less than a million years.
“Because the luminous blue variable stage is so short-lived, you have to be incredibly lucky to catch a star at this stage of its life. This is why they are so rare compared with other types of stars,” the SAAO said.
Most of these stars are shrouded in bipolar or circular nebulae, or cloud, that emits infra-red light, so astronomers search for these blues by searching for these kind of nebulae.
Astronomers found this luminous blue using the SA Large Telescope at Sutherland, and the SAAO’s telescope, and monitored it from 2011.
Kniazev said they were “very lucky” to have discovered the star without having to wait too long in their observations.
Cape Times