The supernova, named SN2016aps, was identified by an international team of astronomers led by the University of Birmingham (England) and which included experts from Harvard, Northwestern University and Ohio University. Experts say the explosion was so bright that it overshadowed its entire mother galaxy.
What they found was a massive supernova in the middle of nowhere and twice as bright as any object previously found in the universe.
Why was this dying star alone?
Typically they are in vast galaxies, but this … was alone. Astronomers believe that the explosion was due to two giant stars that eventually merged in an event known as “pulsation pair instability,” which we had not seen until now.
The supernova in question had five times the blast power of a normal supernova and was almost 10 times greater. They watched the explosion for two years, until it faded to 1% of its maximum brightness. Using these measurements, they calculated that the supernova’s mass was 50 to 100 times greater than our Sun (when “normal” is 8 to 15 solar masses).
How is a supernova measured?
By the total energy of the explosion and the amount of that energy that is emitted as observable light or radiation , according to Matt Nicholl, leader of the work collected by the journal Nature Astronomy.
“Stars with an extremely large mass experience violent pulsations before dying, shaking off a giant gas shell. If the supernova is at the right time, it can hit this shell and release a large amount of energy in the collision . We believe this one it is one of the most compelling candidates for this process so far observed, and probably the most massive, “Nicholl clarifies.
Another puzzle
This supernova still contained new surprises: the initially detected gas was hydrogen , but typically such a massive star would have already lost all its hydrogen through stellar winds long before it began to pulse. But if two slightly less massive stars, of about 60 solar masses, merged before the explosion, it leaves us a more plausible scenario, since lower mass stars retain their hydrogen for longer, while their combined mass is sufficient high enough to cause instability of the star pair.
“Now that we know that such energetic explosions occur in nature, NASA’s new James Webb Space Telescope will be able to see similar events so far away that we can look back in time at the death of the first stars in the universe, ” says Edo Berger, co-author. of the study.
As it was, the explosion was driven by a collision between the supernova and the huge layer of gas, thrown by a star in the years prior to its explosion. An explosion so bright that it overshadowed everything else, making her appear to be alone in the universe. ” We could not see the galaxy where this star was born until the light faded, ” clarifies Peter Blanchard, also a co-author of the study.
Due to the magnitude of its luminosity, it was categorized as a superluminous supernova , a category to which only two more previously recorded supernovae belong.
The research was funded through a research grant from the Royal Astronomical Society, along with grants from the National Science Foundation, NASA, and the European Union Horizon 2020 Framework.
Reference: Matt Nicholl, Peter K. Blanchard, Edo Berger, Ryan Chornock, Raffaella Margutti, Sebastian Gomez, Ragnhild Lunnan, Adam A. Miller, Wen-fai Fong, Giacomo Terreran, Alejandro Vigna-Gómez, Kornpob Bhirombhakdi, Allyson Bieryla, Pete Challis, Russ R. Laher, Frank J. Masci, Kerry Paterson. An extremely energetic supernova from a very massive star in a dense medium. Nature Astronomy, 2020; DOI: 10.1038 / s41550-020-1066-7
