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Eta Car: The Undying Star?
There’s nothing unusual about a star growing so massive that it explodes and disappears into oblivion. It’s called a supernova explosion - the explosion of a massive star that results in a shocking increase in light followed by gradual fading, never to be seen again.
When astrophysicists saw this happen with the star Eta Carinae, in the nebula Carina, they assumed the star had gone supernova...until something unusual happened.
Eta Carinae was first catalogued in 1677, by English scientist Edmund Halley. It is one of the most studied massive stars in the universe because of its size and ability to be photographed by Hubbell. The star is about 100 times more massive than the sun and one-million times more luminous.
It gained much attention in 1843 when it flared from complete darkness, becoming the second brightest star in our galaxy. For ten years Eta Carinae remained on of the brightest burning stars in the sky, until it faded back to total oblivion in 1868.
Scientist had never known a star to flare so brightly, then disappear, then reappear once more. Because Eta Car did not vanish for good, like a true super nova, scientists deemed it as a “supernova impostor.” For years Eta Car acted as a prototype for this new class of supernova impostors.
Just when it started to make sense... scientist have now discounted the “supernova impostor” explanation. Adam Ginsburg, a graduate student in CU’s Astrophysics and planetary Science Department, explains that the star’s odd behavior is likely showing us what happens right before a star undergoes a supernova explosion.
Because this process can take millions of years to occur, astrophysicists have never observed a star this large in this pre-supernova phase.
Ginsburg says that Eta Car is so significant because “it might be showing the last stages of a star’s life before it dies.”