Stellar neutrino energy loss (${ϵ}_{\nu }\ge 0$)

Escaping neutrinos remove energy produced by nuclear reactions or drawn from thermal reservoirs. Pair annihilation, plasma excitations, photoneutrino emission and electron-ion bremsstrahlung provide thermal losses. This reduces photon luminosity or increases the required nuclear and gravothermal supply. At sufficiently extreme collapse densities, neutrino transport must replace a free-escape loss approximation.