Detecting individual stars in the universe filled with distant stars over 9 billion light years from Earth is just impossible but a team of scientists from Japan have just discovered one such lonely star too far from earth to estimate even. It’s about 9 billion light years from Earth.
Searching for stars deep in the space requires constant observations using telescopes and astronomers usually target galaxies, which are a collection of about 10 billion stars, since individual stars are difficult to spot with their faint light.
An international team of researchers, lead by Patrick Kelly, and including University of Tokyo School of Science Assistant Professor and Kavli IPMU Associate Scientist Masamune Oguri, were able to discover the distant individual star, which they have named Icarus, because its brightness had been magnified by 2000 times by the gravity of a larger object in front of it.
They came across the bright but lonely star while observing galaxy cluster MACS J1149+2223, 5 billion light years away, using the Hubble Space Telescope. The researchers noticed a flickering light in the background and a closer analysis revealed that the light was not from a star exploding at the end of its life, but a blue star.
In fact, the galaxy cluster’s gravity had bent space-time to magnify the star’s image, a phenomenon called gravitational lensing, where an object magnifies the light of objects directly behind it.
The discovery of Icarus will help researchers studying dark matter because its interaction with matter has a pronounced effect on the pattern of magnified stars. From the pattern of magnified stars in their study, the researchers were able to exclude the possibility that dark matter is made up mostly of a huge number of black holes with masses tens of times larger than the Sun.
Using this method, manny more magnified stars will be discovered when the upcoming James Webb Telescope becomes operational, and also provide more insight into the properties of dark matter.
The study has been published in Nature Astronomy.