Massive stars don't die quietly. Their deaths – spectacular explosions that can dwarf light from entire galaxies – and now astronomers have discovered the most powerful of them all.
The supernova, named SN2016aps, was discovered in the PanSTARRS Transient Review on February 22, 2016, in a galaxy 4.5 billion light-years from Earth.
Now astronomers have determined that SN2016aps exploded 500 times brighter than typical supernova explosions. They say it is the brightest, most energetic, and perhaps even the most massive supernova we've ever seen.
“SN2016aps is impressive in many ways,” explained astronomer Edo Berger of Harvard University. “Not only is it brighter than any other supernova we've ever seen, it has several properties and features that make it rare compared to other star explosions in the universe.”
Although the brightness peaked in January 2016, SN2016aps observations were not limited to this period. After the supernova was detected in PanSTARRS data, astronomers closely watched as the object dims over time, a process that is still in progress.
They also looked at data from up to a peak in January 2016 and saw SN2016aps clear up a few weeks before the explosion.
The total kinetic energy of SN2016aps was about 5 × 1052 erg, which corresponds to the level of the famous hypernova SN1998bw of 1998, from the progenitor star 25-40 times the mass of the Sun. But the peak brightness of SN2016aps was 4.3 × 1044 erg, more than 40 times brighter than the peak brightness of SN1998bw 1 × 1043 erg.
“The intense energy release from this supernova indicates an incredibly massive stellar progenitor,” Berger said. “This star was at least 100 times the size of our sun.”
Despite this, it is unlikely that this star itself could have produced such a colossal explosion. In fact, there is something really peculiar about it, as spectroscopic observations of the supernova have shown.
“We determined that in the last years before it exploded, the star emitted a massive shell of gas as it pulsed violently,” said astronomer Matt Nicholl of the University of Birmingham. 'The collision of debris from the explosion with this massive shell led to the incredible brightness of the supernova. This added fuel to the fire significantly. '
The study was published in the journal Nature Astronomy.
Sources: Photo: (M. Weiss)
