Astronomers from the University of Copenhagen, among others, have discovered the queen of all supernovas. A stellar explosion twice as bright as any run-of-the-mill supernova. An unprecedented observation, according to one of the researchers.
Upon the death a star, massive amounts of energy are discharged and an explosion occurs - a supernova. Such an event occurs about once every hundred years in our galaxy, the Milky Way. Now, researchers from the University of Copenhagen, among others, have located a supernova that glows brighter than any other seen before.
"We have never experienced a supernova that shines so brightly. Furthermore, it lit up for 600 days, while a 'normal' supernova shines brightly for between 10 and 100 days, before its light is extinguished," says Alejandro Vigna-Goméz, a University of Copenhagen postdoc based at the Niels Bohr Institute's Dark Cosmology Center.
Together with researchers from Harvard, Northwestern, Ohio and Stockholm universities, among others, he has just published a study on their surprising results in the journal Nature Astronomy.
In addition to the supernova known as 'SN2016aps', which glows twice as brightly as 'normal' supernovas, it has an explosive force that is five times as violent as a normal stellar death, the researchers' findings show.
Never seen before
Astronomers have never witnessed such a bright and rapidly exploding star. And now, obviously, a big question remains: what made it possible?
In his PhD dissertation, Alejandro Vigna-Goméz examined why some supernovas are bigger and burn more strongly and longer than others. He studied the death of stars using computer simulations over several years, which resulted in the following theory:
"We believe that this is a case of where two stars merged into one giant star. We believe this to be the case because the level of hydrogen (gas) was so incredibly high for so long after the star began to explode. Normally, this gas is quickly depleted after a star begins to explode and 'die'. But for this supernova, the level remained high until the very end. This suggests that there were two stars, each with an exceptionally large amount of gas, that became one," Vigna-Goméz explains.
Closer to confirming the theory of supernovas
Even though the researchers are yet to be certain that the merging of two stars precipitated this supernova, they are a step nearer to confirming what until now has just been a theory.
"Our discovery is very interesting, because thus far, the emergence of supernovas has been somewhat of a mystery to us. Now we can begin testing the link between our theory and the real-life observations that we've made using space telescopes," explains Alejandro Vigna-Goméz.
"Beyond that, it's just crazy to think of the limitations that we had placed on supernovas, which no longer apply. This study confirms that there is still much to discover about our ever-puzzling universe."
What is a supernova?
- A supernova is the term used for a star when it 'dies', i.e. when it can no longer produce sufficient energy. Stars need gas to burn and light up. When they run out of gas, they burn out. Their encounter with gravity catalyses an explosion, which we call a supernova.
- After a supernova explosion, the star's core remains in the form of a neutron star. If a star was heavy enough, it collapses to become a black hole.