The Study Of The Energy Spectrum Of Stellar Neutrinos

Stars are the main producers of neutrinos in nature.Neutrinos only participate in weak in-teractions,so they have strong penetration and very small scattering cross sections,which make them transparent to all stars.Therefore,neutrinos play an important role in the evolutionary stars.The study of neutrinos is of great significance in different stages of stellar evolution.In this work,we use the MESA code to calculate the neutrino flux of the star with masses between 1 to 9 M_?in different stage of stellar evolution.For the standard model of 1M_?we simulated,we compare the neutrino flux of the star with 1M_?mass at an evolutionary age of4.61×10⁹yr with that of the observed Sun,we find that the simulated values are basically consistent with the observed values.We discuss the neutrino luminosities of stars with different masses from the main sequence to the asymptotic giant branch stages in details.In our work,we find that for the star with mass less than 8 M_?,the neutrino luminosity is mainly provided by nuclear reaction except for the helium flash stage at which neutrinos are derived from the thermal processes.In general,the neutrino luminosity of stars is about10^-1-10^-2lower than the photo luminosity.However,the neutrino luminosity can exceed the photo luminosity when helium flash occurs.For the star with mass of 9 M_?,the neutrino luminosity originates from nuclear reactions until end of the asymptotic giant branch stage.At the end of the asymptotic giant branch stage,the neutrino luminosity results from the thermal process triggered by the gravitation energy releases due to core contraction.