Supernova mass ejection and core hydrodynamics

Conference · Sun Jan 01 00:00:00 EST 1978

OSTI ID:6538347

Colgate, S A

Simplifications that have emerged in the descriptions of stellar unstable collapse to a neutron star are discussed. The neutral current weak interaction leads to almost complete neutrino trapping in the collapse and to an electron fraction Y/sub e/ congruent to 0.35 in equilibrium with trapped electron neutrinos and ''iron'' nuclei. A soft equation of state (..gamma.. congruent to 1.30) leads to collapse, and bounce occurs on a hard core, ..gamma.. = 2.5, at nuclear densities. Neutrino emission is predicted from a photosphere at r congruent to 2 x 10/sup 7/ cm and E/sub ..nu../ congruent to 10 MeV. The ejection of matter by an elastic core bounce and a subsequent escaping shock is marginal and may not be predicted for accurate values of the equation of state. A new concept of Rayleigh-Taylor driven core instabilities is invoked to predict an increased mass ejection either due to an increased flux and energy of neutrinos at second bounce time and, or, the rapid 0.1 to 0.4 second formation of a more energetically bound neutron star. The instability is caused by highly neutronized external matter from which neutrinos have escaped being supported by lighter matter of the lepton trapped core. An initial anisotropy of 10/sup -2/ to 10/sup -3/ should lead to adequately rapid (several milliseconds) overturn following several (2 to 4) bounces. Subsequent to the overturnwith or without a strong ejection shock, a weak ejection shock will allow an accretion shock to form on the ''cold'' neutron star core due to the reimplosion or rarefaction wave in the weakly ejected matter. The accretion shock forms at low enough mass accumulation rate, /sup 1///sub 2/ M/sub solar/ sec/sup -1/, such that a black body neutrino flux can escape from the shock front (kT congruent to 10 MeV, (E/sub ..nu../) congruent to 30 MeV). This strongly augments the weaker bounce ejection shock by heating the external matter in the mantle by electron neutrino scattering (congruent to 10/sup 52/ ergs) causing adequate mass ejection.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6538347
• Report Number(s): LA-UR-78-2030; CONF-7805112-2; TRN: 79-000593
• Resource Relation: Conference: Workshop on supernova and supernova remnants, Sicily, Italy, 14 May 1978; Other Information: Portions of document are illegible
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
NEUTRON STARS
STAR EVOLUTION
SUPERNOVAE
GRAVITATIONAL COLLAPSE
MASS TRANSFER
ANISOTROPY
ELASTICITY
ELECTRON NEUTRINOS
ELECTRONS
ENERGY DEPENDENCE
EQUATIONS OF STATE
FLUX DENSITY
HYDRODYNAMICS
INSTABILITY
IRON
KINETICS
REFLECTION
SHOCK WAVES
STAR MODELS
WAVE PROPAGATION
ELEMENTARY PARTICLES
ELEMENTS
EQUATIONS
ERUPTIVE VARIABLE STARS
FERMIONS
FLUID MECHANICS
LEPTONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MECHANICS
METALS
NEUTRINOS
STARS
TENSILE PROPERTIES
TRANSITION ELEMENTS
VARIABLE STARS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources