Convection, nucleosynthesis, and core collapse

Synthesis of the elements in stars: forty years of progress

“…Strong neutrino losses in the stellar interior during advanced stages of evolution of intermediate mass stars play an absolutely crucial role in determining the relationship between the initial mass of the star and the mass of the white dwarf into which it evolves, but the current-current theory of weak interactions that predicts these losses was not invented until 1958 (Feynman and Gell-Mann, 1958) and the corresponding energy loss rates were not fully worked out until the late 60's (Beaudet, Petrosian, and Salpeter, 1967;Festa and Ruderman, 1969). The possibility of neutral-current contributions to neutrino losses entered physics a decade later with the unified electroweak theory (Weinberg, 1967, Salam, 1968, but calculation of the (15-30 %) contributions of these currents did not begin until several years later (Dicus, 1972, Dicus et al, 1976.…”

“…The total r-process yield is the sum over all ejected mass elements, each of which follows a somewhat different nucleosynthetic pathway as a result of the thermodynamic history and initial neutron excess of each mass element. Hydrodynamics (especially in multiple dimensions) are therefore important in our understanding of neutron-rich heavy element synthesis , Bazan and Arnett, 1994a, 1994b.…”

Pulsar Recoil and Gravitational Radiation Due to Asymmetrical Stellar Collapse and Explosion

“…Interestingly, recent h ydrodynamic calculations [26] of convection during shell oxygen and silicon burning in massive stars and recent theoretical arguments [27] suggest that just before collapse asymmetries in density, v elocity, and composition can be large. Furthermore, rotation might i n teract with convection to further distort the core [28].…”

Explosive Nucleosynthesis

“…Models with M=20 M ⊙ have deserved a particular attention for the theorists, since they are crucial to understand the mixing of radioactive (and other) isotopes, like 56 Ni, in supernova ejecta, which has been deduced from the observations of SN1987A (see section 2.1 above). 2D models of O-burning (Bazan and Arnett 1994) obtain significant mixing beyond the boundaries defined by mixing-length convection. What they obtain are perturbations in density in the oxygen shell that are sufficiently large to "seed" hydrodynamic instabilities, which will mix the "onion-skin" composition of the presupernova (Bazan and Arnett 1998).…”