Nuclear Structure and the Fate of Core Collapse (Type II) Supernova

TL;DR

This paper explores how nuclear structure effects, especially the C/O ratio at helium burning's end, influence whether a Type II supernova results in a neutron star or black hole, highlighting the importance of nuclear reactions in stellar fate.

Contribution

It introduces the significance of the C/O ratio, affected by nuclear structure, in determining the outcome of core-collapse supernovae, and discusses future experimental efforts to measure key nuclear reactions.

Findings

C/O ratio influences supernova remnant type

Future gamma-beam experiments can improve reaction rate measurements

Nuclear structure effects are crucial in stellar evolution models

Abstract

For a long time Gerry Brown and his collaborator Hans Bethe considered the question of the final fate of a core collapse (Type II) supernova. Recalling ideas from nuclear structure on Kaon condensate and a soft equation of state of the dense nuclear matter they concluded that progenitor stars with mass as low a 17-18M$_\odot$ (including supernova 1987A) could collapse to a small mass black hole with a mass just beyond 1.5M$_\odot$, the upper bound they derive for a neutron star. We discuss another nuclear structure effect that determines the carbon to oxygen ratio (C/O) at the end of helium burning. This ratio also determines the fate of a Type II supernova with a carbon rich progenitor star producing a neutron star and oxygen rich collapsing to a black hole. While the C/O ratio is one of the most important nuclear input to stellar evolution it is still not known with sufficient accuracy. We discuss future efforts to measure with gamma-beam and TPC detector the 12C(a,g)16O reaction that determines the C/O ratio in stellar helium burning.