I was watching a video (https://www.youtube.com/watch?v=IZ59_akUUBs) about massive explosions and came across 2007bi. The video stated that this SN happened due to gamma-ray driven antimatter creation.
Apparently, its core being made mostly of oxygen began releasing energetic photons which decayed into electron/positron pairs. Their mutual annihilation caused the core to collapse and triggered the supernova.
I have a couple of questions concerning this.
- Pair-instability supernova happens when a star is about 130 solar masses, but the star here was only at 100 solar masses.... (per Wiki "These stars are large enough to produce gamma rays with enough energy to create electron-positron pairs, but the resulting net reduction in counter-gravitational pressure is insufficient to cause the core-overpressure required for supernova. Instead, the contraction caused by pair-creation provokes increased thermonuclear activity within the star that repulses the inward pressure and returns the star to equilibrium. It is thought that stars of this size undergo a series of these pulses until they shed sufficient mass to drop below 100 solar masses, at which point they are no longer hot enough to support pair-creation. Pulsing of this nature may have been responsible for the variations in brightness experienced by Eta Carinae in 1843, though this explanation is not universally accepted.") [https://en.wikipedia.org/wiki/SN_2007bi ]
Is it more likely the size of the star was wrong, or the that it can happen at lower mass or possibly there was something else at work here?
- Why wouldn't the extra energy from the electron/positron annihilation add more energy to the star's core? It seems counter-intuitive that adding energy reduces the internal supporting pressure. Can someone explain this?