On June 14, 2015, two telescopes at Cerro Tololo (Chile) detected a powerful source of light in the night sky. These instruments belong to Census Supernovas Automated Full Sky (ASAS-SN), a project led by the US that mapping the entire sky every few days for new astronomical phenomena. Since that night, many terrestrial and space telescopes have launched the race to observe the same flash, then, according to preliminary analysis, and to the surprise of astronomers, this is the most powerful stellar explosion ever recorded.
The international team of ASAS-SN says a study published today in Science by everything that has been able to find out about this enigmatic supernova, dubbed ASASSN15lh. The first thing that has surprised you do not like any of the more than 200 supernovae have been discovered since 2014. It is twice as bright as any other stellar explosion recorded 20 times brighter than all the stars in our galaxy together. In fact, this monster is so rare, as unclassifiable, which its discoverers can not even explain how much energy can be released without violating basic laws of physics.
After the first observations, astronomer José Prieto, who works at the Millennium Institute of Astrophysics and the University Diego Portales of Chile and a member of ASAS-SN team, was the first to propose an explanation. “I thought that one possibility is that it was a superluminous supernova, a kind of rare objects,” he explains. These supernovae were discovered only two decades ago and it is still unclear what kind of stars occur when implode at the end of their lives.
The team used their own instruments and other telescopes to determine the chemical composition and distance from the star. The results have confirmed the hunch Prieto and indicate that is 3,800 million light years, that is, the flash captured on June 14 took place when all earthlings were simple microbes.
So far, astronomers believed that these supernovae stars that produce them, to exploit, are at its core a neutron star that rotates on itself so fast that creates a strong magnetic field. They are known as magnetars. After the collapse of its outer layers, these fall into the core and are thrown forming a supernova. If to that we add the energy of the magnetic field in the core, the result is one of the biggest bursts of energy that can be observed in the universe.
But the newly discovered supernova is more powerful even than the magnetar more conceivable. “The energy that is radiated so far is so great that bankruptcy this model, the magnetar would have to rotate too fast and not hold, it would break, so to speak,” Prieto said. So, a humble Subo Dong, lead author of the study recognizes. “The honest answer is we do not know where the energy of ASASSN15lh comes”
Although not visible to the naked eye because of its remoteness, the supernova is still shining, no one knows how long. Its discoverers now plan to use the Hubble Space Telescope to try to reveal his secret.
By Nuño Dominguez / El País
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