Astronomers in the US have been able, with the help of the Hubble Space Telescope, to photograph the farthest individual star that has been observed so far, Icarus, at a distance of nine billion light-years from the Earth.
Astronomers have seen much longer galaxies, supernovae explosions, or other explosive phenomena such as gamma-ray bursts, but not even so distant individual regular stars such as the sun. “Icarus” is about 100 times as far away as the second ever distant star seen so far.
“For the first time we see at a distance of nine billion light years a single natural star, not a super-vow, nor a gamma ray,” said Professor of Astronomy Alex Philipenko of the University of California-Berkeley.
The researchers who made the publication in the Astronomy Journal “Nature Astronomy” used the gravitational lens method to see the Icarus star (which has the scientific name MACS J1149 +2223 LS1). With this method, a closest object – galaxy or star-magnifies the light of a more distant object behind it.
Scientists can see the most distant galaxies, because they shine with the brightness of the billions of stars they contain, while a super-nova, which is often brighter than a galaxy can be seen in almost all the universe at distances up ten billion years.
But this is not possible for individual stars, which are impossible to see as individual objects, after the distance of about 100 million light years from the earth. However, thanks to the gravitational effect, it is possible to magnify an object that is far away, making it observable.
Usually, the gravitational lens magnifies a galaxy up to 50 times, but in this case the Icarus star has been magnified more than 2,000 times. The role of the gravitational lens for the “Icarus” he played both an intermediate galaxy, no matter how another star in this galaxy, which – in a rare situation – perfectly aligned between the much more distant star and Hubble.
The Icarus light analysis revealed that it is a blue supergy, a type-B star, much larger in size, mass, temperature and brightness than our sun – perhaps even hundreds of thousands of times brighter than ours our star. Its surface temperature – more than twice as high as our sun – ranges from 11,000 to 14,000 degrees Celsius.
More such distant stars can be discovered in the future by Hubble, which will continue to operate by mid-2021 and, even more so, by its successor, the much more powerful James Webb space telescope to be launched in mid-2019.