Electron capture in stars

Understand

Electron captures on nuclei play an essential role for the dynamics of several astrophysical objects.

• The capture rate can be derived in perturbation theory where allowed nuclear transitions (Gamow-Teller transitions) dominate, except at the higher temperatures achieved in core-collapse supernovae where also forbidden transitions contribute significantly to the rates.
• There has been decisive progress in recent years in measuring Gamow-Teller (GT) strength distributions using novel experimental techniques based on charge-exchange reactions.
• These measurements provide not only data for the GT distributions of ground states for many relevant nuclei, but also serve as valuable constraints for nuclear models which are needed to derive the capture rates for the many nuclei, for which no data exist yet.