CENTRAL TEMPERATURE OF THE SUN CAN BE MEASURED VIA THE BE-7 SOLAR-NEUTRINO LINE

A precise test of the theory of stellar evolution can be performed by measuring the difference in average energy between the neutrino line produced by Be-7 electron capture in the solar interior and the corresponding neutrino line produced in a terrestrial laboratory. The high temperatures in the center of the Sun broaden the line asymmetrically, FWHM = 1.6 keV, and cause an average energy shift of 1.3 keV. The width of the Be-7 neutrino line should be taken into account in calculations of vacuum neutrino oscillations.