The star, to which the researchers gave the nickname Icarus, could only be observed thanks to the gravitational lens effect. Under normal circumstances, its light would be too weak to be harvested from Earth, as the University of Geneva announced on Monday.
The gravitational lensing effect occurs when an object of large mass, such as a galaxy, passes between the observer and the star it is aiming at. The mass of the galaxy amplifies the light emitted by the star. So this is more visible.
This astronomer Patrick Kelly of the University of Minnesota and his colleagues at the University of Geneva and the ETH made themselves Lausanne advantage. An accumulation of galaxies some five billion light-years from Earth helped the scientists identify the star with the high-resolution Hubble telescope. The researchers reported on it in the journal “Nature Astronomy”.
“For the first time, we have observed a star that is nine billion light-years away,” says Jean-Paul Kneib, a professor at the Astronomy Laboratory of the Federal Institute of Technology in Lausanne. Icarus “is at least 100 times farther away than the most remote star we’ve ever studied, apart from the explosions of the supernovae,” says Kelly.
In the case of Icarus, whose official name is “MACS J1149 + 2223 Lensed Star 1”, the galaxies amplified the star’s light by a factor of 2000 rather than by a factor of 600, as would have been expected. Therefore, the researchers assume that the galaxies did not provide alone for this effect. It can be assumed that another star has reinforced the effect.
To observe such a rare phenomenon is a stroke of luck for the scientists. “It has enabled us to gather a great deal of information about the star and its surroundings,” says Antonio Cava of the Department of Astronomy at the University of Geneva. Thus, Icarus could be classified as a blue supergiant, which shines several thousand times stronger than the sun.