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One of the largest known stars in the cosmos is poised for catastrophe.<\/p>\n
After witnessing the massive object undergo a dramatic transformation, a team of astronomers say the star is on the verge of exploding in a powerful supernova, they report in a new study<\/a> published in the journal Nature Astronomy. Or, they speculate, it could collapse directly into a black hole due its incredible mass.<\/p>\n Since it was first discovered some five decades ago, the star, WOH G64<\/a>, has been classified as a red supergiant<\/a> with a mass thirty times that of the Sun. But it\u2019s the supergiant\u2019s size that truly boggles the mind. With a radius over 1,500 times that of the Sun, it would stretch past the orbit of Jupiter if it were placed in the middle of our solar system.<\/p>\n Supergiant stars are short-lived. WOH G64 is only around five million years old, when our star is 4.6 billion. But they have a taste for the spectacular, ranking among the brightest stars in the cosmos, on top of their epic scale. This one is located some 165,000 light years away in a dense region of space called the Large Magellanic Cloud, a dwarf galaxy that orbits the Milky Way. It\u2019s a fertile star-forming region packed with enough material to give birth to oversized behemoths like WOH G64.\u00a0<\/p>\n Being born so massive means that the stars grow quickly. As WOH G64 aged, it quickly burned through the hydrogen at its core and resorted to burning helium. This second wind of heating caused the star\u2019s outer layers to quickly expand \u2014 which, as the core contracts, allows more heat to dissipate. This causes the star to cool, resulting in its red appearance. And thus, a red supergiant is formed.<\/p>\n But WOH G64 may be transforming yet again into something even more awe-inspiring. The astronomers noticed that, in 2014, WOH G64\u2019s color and temperature dramatically but smoothly changed in under a year, suggesting that it may be evolving into a yellow hypergiant. The largest of these stars are so voluminous<\/a> that they can fit several billion Suns inside them.<\/p>\n \u201cYellow hypergiants are extremely rare because they represent a short-lived transitional phase between the red supergiant stage and the eventual supernova explosion,\u201d lead author Gonzalo Mu\u00f1oz-Sanchez at the National Observatory of Athens told Space.com<\/a>. \u201cConsequently, only a small number of confirmed yellow hypergiants are currently known, amounting to just a few tens of objects.\u201d<\/p>\n The transformation into a hypergiant occurred, the astronomers propose, after WOH G64 ejected a large portion of its outer layers into space. This was spurred by interactions with a companion star which stripped material from the WOH G64\u2019s surface to form a vast shell of hydrogen \u2014 a common envelope<\/a> \u2014 that swallowed both stars.<\/p>\n But the astronomers also can\u2019t rule out the possibility that this transformation is taking place independently of the companion star\u2019s interference.<\/p>\n \u201cEven though the system is binary, the transition may have been driven by intrinsic stellar processes. In this case, the star may have undergone an extraordinary eruptive episode lasting more than 30 years and is now returning to a yellow, quiescent state,\u201d Mu\u00f1oz-Sanchez told Space.com. \u201cBoth possibilities are extremely rare, and witnessing either occur on human timescales is nearly unprecedented.\u201d<\/p>\n Its unclear nature makes it difficult to predict how it will die, but it\u2019s guaranteed to be a catastrophe of some kind, and one that will happen \u201csoon\u201d in cosmic terms, according to Mu\u00f1oz-Sanchez, meaning anywhere from hundreds to thousands of years. The giant star could go supernova, exploding dramatically or instantly inverting into a black hole. Or it could collide with its companion star. <\/p>\n \u201cThe fate of stars with initial masses between 23 and 30 solar masses after evolving into red supergiants is still uncertain,\u201d Mu\u00f1oz-Sanchez told Space.com. WOH G64\u2019s behaviour could suggest that red supergiants become yellow hypergiants before finally winking out.<\/p>\n