Icarus – The Most Distant Star

There are some special features surrounding this story. Not the star itself, but rather its position and observation. Icarus (also denominated as MACS J1149 Lensed Star 1 or MACS J1149+2223 Lensed Star 1) is at a staggering 9 billion light years away from us. The light of this blue supergiant took 9 billion years to reach us, beginning its voyage through space when the Universe was only 30% of its current size. 
Blue supergiants such as Icarus don’t last for long, as they evolve from high-mass stars of 10 to 300 solar masses after burning through their main sequence stage. These giant stars only last for a couple million years until they move into their blue supergiant phase, thus becoming highly unstable, with episodes of huge mass loss, eventually transitioning into red supergiants, yellow supergiants or yellow hypergiants. These later stages only last for some tens of thousands of years or less. During the red/yellow supergiant phase a star like this might go through various blue supergiant loops before exploding into a supernova. Another characteristic of these stars is their incredible luminosity. Icarus, for instance, is around 850.000 solar luminosities. So if you asked yourself, while starting to read this post, if Icarus might still be out there, the answer is: most definitely not. This star, of at least 33 solar masses lived fast and died hard (inspiring Bruce Willis to do the same in the franchise). 
The discovery of this star by astronomers was by pure accident, as it was observed by the Hubble Space Telescope during the studies on the SN Refsdal supernova, the first detected multiply-lensed supernova, at a distance of 14.4 billion ly and a lookback time of 9.34b ly. During the studies, over a period of 3 years (2013 to 2016) they noticed a point gradually becoming more luminous and determined that the point was a star magnified through gravitational lensing. 
It is unclear when this incredibly faint dot will seize to appear through our telescopes, as a star like Icarus cannot live for more than 9 million years from its protostar stage to its collapse into a black hole, but considering the growth in luminosity during the 2013-2016 observations, it’s clear that Icarus is projecting its final stages of existence before exploding into a supernova. – Roman Alexander