There’s a lot of universe to explore out there, so we’re constantly finding the next “oldest” or “biggest” object or phenomenon. Today, a team of researchers from the University of Birmingham say they’ve identified the brightest supernova explosion on record, and it may be a previously unseen type of stellar explosion that could confirm some long-held ideas about stellar life cycles.
The explosion in question was truly massive, so we’re lucky it took place about 3.6 billion light-years away. The supernova, known officially as SN2016aps, exhibited an unusual energy profile that sets it apart from other such events. In a typical supernova, the emitted radiation is less than 1 percent of the total energy output. Observations of SN2016aps show that its radiation was five times higher than a “normal” supernova. That makes it the brightest supernova ever observed.
As the name implies, SN2016aps was initially spotted in 2016. The team first identified it using the Panoramic Survey Telescope and Rapid Response System in Hawaii. Follow up observations were made with the Hubble Space Telescope for two more years. Over that time, the supernova’s brightness faded to just 1 percent of its peak output.
Because the explosion took place so far away, it also happened in the distant past. Therefore, the team has speculated that it could be the first-ever example of a “pulsational pair-instability” supernova. In such an event, two large stars in a binary system spiral closer and closer until they merge. The instability of two stars coming together causes them to explode in a supernova — potentially a very, very large supernova. Astronomers have hypothesized about pulsational pair-instability supernovae, but we’ve never confirmed their existence observationally.
Calculations suggest the system that produced SN2016aps had between 50 and 100 times the mass of the sun. Its high brightness output may be a result of the supernova shockwave catching up to the gas expelled from the system before the main explosion. This is something astronomers would expect to find in a pulsational pair-instability supernova. The team also detected mostly hydrogen gas around the event, but single massive stars would have burned through their hydrogen. That also supports the idea that SN2016aps occurred after two smaller, younger stars merged.
Astronomers hope that the upcoming James Webb Space Telescope will be able to spot similarly distant objects to find more of these unusual supernovae.
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