Pair-instability evolution and explosions in massive stars

Understand

Very massive stars are radiation pressure dominated.

• Before running out of viable nuclear fuel, they can reach a thermodynamic state where electron-positron pair-production robs them of radiation support, triggering their collapse.
• Thermonuclear explosion(s) in the core ensue.
• These have long been predicted to result in either repeated episodic mass loss (pulsational pair instability), which reduces the mass available to eventually form a black hole, or, if sufficient energy is generated, the complete unbinding of all stellar material in one single explosive episode (pair instability supernova), which leaves behind no black hole.