Electron capture in stars.

Area of Science:

• Nuclear astrophysics
• Computational physics
• Stellar evolution

Background:

• Electron capture on nuclei is fundamental to astrophysical phenomena such as supernovae and neutron stars.
• These processes occur under extreme conditions of finite temperature and density, involving degenerate relativistic electron gases.
• Gamow-Teller (GT) transitions are dominant, but forbidden transitions become significant at higher temperatures.

Purpose of the Study:

• To review recent experimental and theoretical progress in determining stellar electron capture rates.
• To highlight the impact of improved capture rates on astrophysical models.
• To provide accurate data for nuclei relevant to stellar evolution and nucleosynthesis.

Main Methods:

• Utilizing novel experimental techniques like charge-exchange reactions to measure GT strength distributions.
• Developing advanced nuclear many-body models and computational tools for theoretical calculations.
• Employing large-scale shell-model diagonalization for accurate rate derivations under challenging astrophysical conditions.

Main Results:

• Significant progress in measuring GT strength distributions for ground states of relevant nuclei.
• Development of sophisticated nuclear models constrained by experimental data.
• Improved modeling of stellar capture rates, particularly for core-collapse supernovae and intermediate-mass stars.

Conclusions:

• Accurate electron capture rates are essential for understanding core-collapse supernovae, thermonuclear supernovae, and neutron star crust dynamics.
• Experimental data and advanced theoretical models are crucial for validating and deriving these rates.
• Enhanced understanding of stellar processes and nucleosynthesis is achieved through these improved capture rate calculations.