A rare cosmic alignment allowed the Hubble Space Telescope to observe Icarus, a blue supergiant located nine billion light-years away and the most distant “ordinary” star from Earth.
As reported by Berkeley News, University of California researchers found the star through gravitational lensing, and they were able to magnify Icarus 2,000 times.
Icarus: How Astronomers Found A New Star
Lead author Patrick Kelly, previously of the University of California, Berkeley but currently a faculty member of the University of Minnesota, was observing the supernova SN Refsdal using Hubble Space Telescope images when he found the blue supergiant.
MACS J1149 Lensed Star 1, nicknamed Icarus, was discovered while observing images taken through the gravitational lens peering through a massive galaxy cluster located five billion light-years away.
Kelly and his team analyzed the images and discovered Icarus, a blue supergiant which is hotter, bigger, and possibly brighter than the sun.
In normal circumstances, gravitational lensing can only magnify objects 50 times. However, Icarus has been magnified 2,000 times, which led the researchers to the conclusion that a star about the same size as the Sun passed between Icarus and the Hubble Space Telescope. This alignment magnified the background thousands of times, thus revealing the blue supergiant located nine billion light-years away.
Alex Filippenko, co-author of the study and an astronomy professor at UC Berkeley, explained just how powerful nature is at magnifying objects.
“There are alignments like this all over the place as background stars or stars in lensing galaxies move around, offering the possibility of studying very distant stars dating from the early universe, just as we have been using gravitational lensing to study distant galaxies. For this type of research, nature has provided us with a larger telescope than we can possibly build!”
Ordinary Stars And Why They Matter
Observing stars, even with the powerful features of the Hubble Space Telescope, continues to be a big challenge for astronomers. However, they got lucky with Icarus, which is located nine billion light-years away. At this distance, it’s easier to observe star explosions or an entire galaxy rather than an individual star.
More than halfway across the universe, an enormous blue star nicknamed Icarus is the farthest individual star ever seen. Using gravitational lensing, Hubble was able to pinpoint this faraway star and set a new distance record: https://t.co/eylSuu296c pic.twitter.com/DxbV3YCQNr
— Hubble (@NASAHubble) April 2, 2018
Luckily, a rare alignment allowed researchers to study the ordinary star. Ordinary stars are those which are capable of generating helium by fusing hydrogen at its core, similar to how the sun functions. These ordinary stars could either explode into a supernova or become a white dwarf.
The images from the Hubble Space Telescope that revealed the existence of Icarus were captured in late April 2016 and April 2017. Kelly explains that the star is 100 times farther than individual stars astronomers can study.
The discovery of Icarus helped researchers reject the theory that dark matter consists of several primordial black holes located inside galaxy clusters. Aside from that, it also provides insight on how a galaxy cluster is made up, particularly, the dark matter and normal matter composition.
The study on the discovery of the blue supergiant Icarus using images from the Hubble Space Telescope was published in Nature Astronomy.