The NASA / ESA Hubble Space Telescope has discovered the farthest star ever observed. It is MACS J1149 + 2223 Slowed Star 1, but the team of scientists has decided to name it Icarus , in honor of the mythological character who got too close to the Sun. Not surprisingly, this star is twice as hot as the Sun and its light has taken 9 billion light years to reach Earth.
It is located in a spiral galaxy so distant that we would have to travel more than half the universe to find it.
The international team of astronomers who signed the discovery in the journal Nature Astronomy, comments that the finding was made possible thanks to a gravitational lens, a huge ‘magnifying glass’ created by a cluster of galaxies.
The surprising thing is that, until now, we have only been able to observe supernovae at as remote a distance as this individual star, and typically would not have been able to detect it. In fact, we can only observe individual stars within the Milky Way or galaxies in our cosmic neighborhood , but not further afield, not even using the most powerful telescopes on the planet.
However, thanks to a gravitational lens generated by a galaxy cluster, astronomers have been able to amplify its brightness and finally detect it.
” It is a huge blue star, whose photons have taken 9,000 million light years to reach Earth, which is equivalent to 70% of the age of the universe, but as the universe is expanding, now the star is 14,000 millions of light years “, explains Pablo Pérez González, belonging to one of the Spanish institutions that has participated in the discovery.
“This is the first time we have seen an individual star magnified. We are able to see very distant galaxies, but this star is 100 times farther away than the next individual star we can study, except if we count supernova explosions as a star,” adds Patrick Kelly, a co-author of the study.
A gigantic magnifying glass
The phenomenon called ‘gravitational lensing’ allows, as in this case, a very massive cluster of galaxies to act like a large cosmic magnifying glass, amplifying the light from more distant objects. By combining this natural lens with the resolution and sensitivity of the Hubble telescope, it has been possible to detect and analyze that distant star, Icarus.
According to experts, Icarus is a blue supergiant star; a star much larger, massive, hotter, and possibly thousands of times brighter than the Sun and its discovery opens the door to a new way of looking at the universe for astronomers , who will soon start looking for more similar events when the magnificent James Webb Space Telescope (JWST) is launched in 2019 and replaces the mythical Hubble.
Reference: Patrick Kelly, José M. Diego, Steven Rodney, Pablo G. Pérez González, Tom Broadhurst, Ismael Pérez Fournon et al .: “Extreme magnification of an individual star at redshift 1.5 by a galaxy-cluster lens”. SA Rodney, T. Broadhurst, A. Molino, JM Diego et al .: “Two peculiar fast transients in a strongly lensed host galaxy”. Nature Astronomy ,, 2018.
