Neutrinos and Asteroseismology of Stars over the Helium Flash

Abstract

The helium flash, occurring in stars of 0.6–2.0 M ⊙ at the end of the red giant branch, is not observable via optical means due to the energy of the process being used to lift the core out of degeneracy. Neutrinos, which are linked to the ignition of reactions triggered during the flash and serve as the only cooling process in the inert core, can help characterize changes in internal structure. In this work, we create 18 stellar models across three mass and six metallicity values, chosen in the context of the stellar abundance problem, to compare the evolutionary path up to and probe the helium flash by conducting a detailed study of neutrino emission throughout this crucial phase of stellar evolution. We demonstrate how thermal neutrino emissions could have an imprint on global asteroseismic parameters and use them as an additional tool to infer the impact of compositional changes. We find that a precision of 0.3 μHz in the determination of Δν is enough to distinguish between between the two most prominent solar composition models and confirm that asteroseismic observation can be enough to classify a star as undergoing the process of helium subflashes. We also predict nuclear neutrino emission fluxes and their evolution for all relevant sources.