Science

Rare Cosmic Alignment Reveals The Most Distant Star Ever Seen

Rare Cosmic Alignment
Photo by Hubble Space Telescope / ESA

While observing a rare cosmic alignment, scientists managed to observe a star located about nine billion light-years away via the Hubble Space Telescope. This star is known as Icarus, which is a blue supergiant. Scientists estimate it to be the most distant ordinary star from our planet ever seen so far.

According to a report by Berkeley News, researchers from the University of California discovered Icarus using gravitational lensing. The rare cosmic alignment allowed them to observe it, magnifying Icarus 2,000 times. Researchers published their findings in the journal Nature Astronomy.

The discovery was noted when Patrick Kelly, a faculty member of the University of Minnesota, who previously was a postdoctoral scholar at the University of California, Berkeley, observed a supernova SN Refsdal via Hubble Space Telescope. It wasn’t much later that he discovered the blue supergiant Icarus.

Scientifically, the blue supergiant is known as MACS J1149 Lensed Star 1, although it was easier to nickname it Icarus.

Kelly and his colleagues were studying the Hubble images of a massive galaxy cluster about five billion light-years away from Earth. A phenomenon known as gravitational lensing – light being bent by a galaxy cluster between a distant object and the observer, magnifying the object – was observed and the researchers were able to see the star, Icarus. The blue supergiant is warmer, bigger, and most likely brighter than our sun.

Normally, gravitational lensing can only magnify objects 50 times. However, Icarus was magnified 2,000 times, which made the team determine that an individual star about the same size of the Sun passed between the blue supergiant and the Hubble Space Telescope. This rare cosmic alignment allowed for magnification of the background thousands of times, which exposed Icarus to the scientists, at an amazing nine billion light-years away.

Alex Filippenko, one of the authors of the study, and a professor of astronomy at UC Berkeley said as per the statement: “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!”

Fortunately for the team, this rare cosmic alignment let the researchers learn more about the blue supergiant, which is also an ordinary star. Those stars can generate helium and they do that by fusing hydrogen at its core. It is quite similar to how our sun works. According to the scientists those stars either explode or become white dwarfs.

Scientists observed the images that contained the discovery of Icarus in late April 2016 all the way up to April 2017. According to Kelly, the discovered star is 100 times further compared to the individual stars that astronomers normally study. Their discovery also debunks a theory suggesting that dark matter consists of many primordial black holes that live inside galaxy clusters. Additionally, the discovery sheds light on how galaxy clusters form, especially their dark matter and regular matter composition.