Pulsational Pair-instability supernova (PPISN)
Star that PEELS like onion before explosion...
Stars between 80 - 140 solar mass has a distinctive evolutionary path from its relative, the core-collapse supernova (10 - 40 solar mass). For lower mass stars, they evolve "quietly" by fusing light elements (H, He, C...) to heavy elements (Si..., up to Fe) until the iron core exceeds Chandrasekhar mass and collapse. For PPISN, the evolution is vigorous that at some point, the burning can trigger pulsation which ejects some matter near surface away from star.
The ejected matter forms the circumstellar medium. During the final explosion, the high velocity ejecta collides with the circumstellar medium (bottom panel) and creates a bright event called the superluminous supernova.
This topic is interesting because it can explain the rapidly evolving supernovae observed in supernova surveys, and some massive black hole that is deduced from gravitational wave events. I mainly use the stellar evolution code MESA to compute the models.
(top) The star becomes over-compressed due to pair-production instability. (middle) Cartoon showing the expanded core contracts, while outer matter is ejected. (bottom) Explosion of a PPISN where the ejecta collides with the circumstellar medium created during pulsation, forming a super-luminous supernova
Origin of massive black hole in GW170729
Recent detection of gravitational wave by binary black hole merger events provides us precious information about the mass distribution of black hole.
The massive of some black hole is beyond that maximum value created by core-collapse supernova (<80 solar mass). The figure shows the recent gravitational wave events and their implied black hole masses.
The PPISN model can explain two of the most massive black holes detected. In event GW170729, the primary black hole has a mass ~50 solar mass, which is marginally below the transition to pair-instability supernova where no remnant is left.
Connecting to super-luminous supernova (AT2018cow)
PPISN has a distinctive light curve because of the circumstellar medium. The final collapse creates ejecta, which interacts with this medium. It results in a super-luminous supernova.
My recent project includes using PPISN to explain the famous COW (At2018cow). This object has a very fast rising time (~3 days) and is very bright (~4e44 erg at peak luminosity). I explain this object by my PPISN model with a He-core of 42 solar mass.
For illustration I also list out the individual contribution of different components. For example, the CSM interaction contributes to the light curve before day 20, while radioactive decay contributes to that after day 20.