Neutrinos and supernova collapse

Conference · Thu Oct 30 04:00:00 EST 1980

OSTI ID:6772274

Colgate, S A; Petschek, A G

The neutrino emission resulting from stellar collapse and supernova formation is reviewed. The electron capture and consequent neutronization of the collapsing stellar matter at the end of evolution determines both the initial adiabat of core collapse as well as the trapped lepton fraction. The initial lepton fraction, Y/sub l/ = .48 supplies the pressure for neutral support of the star at the Chandrasekhar limit. High trapping values, Y/sub l/ = .4, lead to soft core collapses; low values to harder collapses. The value of Y/sub l/ is presently in dispute. The neutrino emission from initial electron capture is relatively small. A strong core-bounce shock releases both electron neutrino as well as thermal muon and tau neutrinos. Subsequent neutrino emission and cooling can sometimes lead to an unstable buoyancy gradient in the core in which case unstable core overturn is expected. Calculations have already shown the importance of the largest possible eddy or equivalently the lowest mode of overturn. Present models of low lepton trapping ratio lead to high entropy creation by the reflected shock and the stabilization of the core matter against overturn. In such cases the exterior matter must cool below an entropy of approximately s/k approx. = 2 to become unstable. This may require too long a time approximately one second for neutrino cooling from a neutrinosphere at rho approx. = 2 x 10/sup 12/ g cm/sup -3/. On the other hand, high values of Y/sub l/ such as .4 lead to softer bounces at lower density and values of the critical stabilizing entropy of 3 or higher. Under such circumstances, core overturn can still occur.

• Research Organization: Los Alamos Scientific Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6772274
• Report Number(s): LA-UR-80-3163; CONF-800775-1
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELEMENTARY PARTICLES
ERUPTIVE VARIABLE STARS
FERMIONS
GRAVITATIONAL COLLAPSE
LEPTONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
NEUTRINOS
STAR EVOLUTION
STAR MODELS
STARS
SUPERNOVAE
VARIABLE STARS