Astronomers Detect The Most Powerful Star Explosion We’ve Ever Observed

Massive stars don’t die quietly. Their deaths are spectacular explosions that can outshine entire galaxies – and now, astronomers have identified the most powerful of these exploding stars we’ve ever witnessed.

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Tau.Neutrino said:

Astronomers Detect The Most Powerful Star Explosion We’ve Ever Observed

Massive stars don’t die quietly. Their deaths are spectacular explosions that can outshine entire galaxies – and now, astronomers have identified the most powerful of these exploding stars we’ve ever witnessed.

more…

“The supernova, named SN2016aps, was observed by the PanSTARRS Survey for Transients on 22 February 2016, in a galaxy 4.5 billion light-years from Earth. Now, astronomers have determined that SN2016aps was 500 times brighter than typical supernova explosions. It is, they say, the brightest, most energetic and maybe even the most massive supernova we’ve ever seen – pushing it towards the category of hypernova.”

“SN2016aps had been brightening in the (two months) prior to the big kaboom, dating back to December 2015.”

“The total kinetic energy of SN2016aps was around 5×10^52 erg, putting it about on a par with the famous 1998 hypernova SN1998bw, from a progenitor star 25 to 40 times the mass of the Sun. But the peak luminosity of SN2016aps was 4.3×10^44 erg, over 40 times brighter than SN1998bw’s 1×10^43 erg peak luminosity.”

Hold on, so this is same peak energy but different peak brightness. That’s not only interesting, it ought to be impossible. But … see the following.

“At birth, this star was at least 100 times the mass of our Sun. Even so, it’s unlikely that this star could have produced such a colossal explosion on its own. In fact, there’s something really peculiar about it, as spectroscopic observations of the supernova revealed. We determined that in the final years before it exploded, the star shed a massive shell of gas as it violently pulsated. The collision of the explosion debris with this massive shell led to the incredible brightness of the supernova. It essentially added fuel to the fire.”

Massive stars, and even very ordinary stars, shed a lot of mass before they explode. For the supernova 1987a in the Magellanic cloud, for example, a ring of matter lit up like a Christmas tree 10 years after the explosion. Closer in and it would light up faster and brighter.

“That SN2016aps held onto its hydrogen prompted us to theorise that two less massive stars had merged together, since lower mass stars hold onto their hydrogen for longer”.

“A pulsational pair-instability supernova is a supernova impostor event that generally occurs in stars at around 100 to 130 solar mass (M☉), as opposed to a typical pair-instability supernova which occurs in stars of 130 to 250 M☉. Stars like this are massive enough that the gamma rays are energetic enough to produce electron-positron pairs but it is generally not enough to completely blow up the star. The carbon-burning core compresses and heats up as the electron-positron pairs remove pressure from outwards photons, until the oxygen stored in the core suddenly ignites in a thermal runaway reaction which exerts a pulse outwards, then stabilises. The star will eject a large amount of its mass, which will generally bring it under 100 M☉ where it will typically undergo a normal core-collapse supernova.

“It is possible that this is what occurred during the 1843 eruption of the primary star of the Eta Carinae star system although there is no substantial evidence supporting this.”

I was wondering about that.