Fr.: instabilité de paire
An instability arising from the → pair production inside a → massive star leading to energetic → supernova explosions. The pair instability occurs when, late in the star's life, the core reaches a sufficiently high temperature after → carbon burning, a condition in which the pair production can take place. The pairs of electron and positron annihilate to form a neutrino and an anti-neutrino. Consequently, the pressure drops and the outer layers fall in onto the core. The temperature and pressure increase rapidly and eventually titanic nuclear burning causes an extraordinary explosion with energies higher than 1051 erg. See also → pair-instability supernova and → pulsational pair-instability supernova.