Book contents
- Frontmatter
- Contents
- Participants
- Preface
- Acknowledgements
- Observations of Supernovae and the Cosmic Distance Scale
- Type Ia Supernovae
- Type Ib and Type II Supernovae
- Recent Advances in Supernova Theory
- Dynamics of Type-II Supernovae
- Hydrodynamics and Theoretical Light Curves of SNe II
- Instabilities and Mixing in Type II-P and II-b Supernovae
- Progenitors and Hydrodynamics of Type II and Ib Supernovae
- Statistical Analysis of Supernovae and Progenitors of SN Ib and SN Ic
- Supernova Nucleosynthesis in Massive Stars
- Nuclear Weak Processes in Presupernova Stars
- SN 1987A, SN 1993J, and Other Supernovae
- Supernovae and Circumstellar Matter
- Supernova Remnants
- Catalogues
- List of Contributed Papers
Nuclear Weak Processes in Presupernova Stars
from Type Ib and Type II Supernovae
Published online by Cambridge University Press: 04 August 2010
- Frontmatter
- Contents
- Participants
- Preface
- Acknowledgements
- Observations of Supernovae and the Cosmic Distance Scale
- Type Ia Supernovae
- Type Ib and Type II Supernovae
- Recent Advances in Supernova Theory
- Dynamics of Type-II Supernovae
- Hydrodynamics and Theoretical Light Curves of SNe II
- Instabilities and Mixing in Type II-P and II-b Supernovae
- Progenitors and Hydrodynamics of Type II and Ib Supernovae
- Statistical Analysis of Supernovae and Progenitors of SN Ib and SN Ic
- Supernova Nucleosynthesis in Massive Stars
- Nuclear Weak Processes in Presupernova Stars
- SN 1987A, SN 1993J, and Other Supernovae
- Supernovae and Circumstellar Matter
- Supernova Remnants
- Catalogues
- List of Contributed Papers
Summary
The structure and the size of the core of massive presupernova stars are determined by the electron fraction and entropy of the core during its late stages of evolution; these in turn affect the subsequent evolution during gravitational collapse and supernova explosion phases. Beta decay and electron capture on a number of neutron rich nuclei can contribute substantially towards the reduction of the entropy and possibly the electron fraction in the core. Methods for calculating the weak transition rates for a number of nuclei for which no reliable rates exist (particularly for A > 60) are outlined. The calculations are particularly suited for presupernova matter density (ρ = 107 − 109 g/cc) and temperature (T = 2 − 6 × 109 °K). We include besides the contributions from the ground state and the known excited states, the Gamow-Teller (GT) resonance states (e.g. for beta decay rates, the GT+ states) in the mother nucleus which are populated thermally. For the GT strength function for transitions from the ground state (as well as excited states) we use a sum rule calculated by the spectral distribution method where the centroid of the distribution is obtained from experimental data on (p,n) reactions. The contribution of the excited levels and GT+ resonances turn out to be important at high temperatures which may prevail in presupernova stellar cores.
Presupernova Evolution of Massive Stars
Beta decay (β−) and electron (e−) capture of neutron rich nuclei play important roles in determining presupernova core structure (Nomoto et al, 1991).
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- Supernovae and Supernova RemnantsIAU Colloquium 145, pp. 165 - 172Publisher: Cambridge University PressPrint publication year: 1996