The Sun and Cosmic Rays

Abstract

A brief summary is given of the relevance of the sun to cosmic rays. It is pointed out that the sun generates low energy particles and is therefore a useful test-source, at least for the injection of cosmic rays which are then accelerated to higher energies by other mechanisms — such as supernova remnant shocks. The importance of the modulation of Galactic cosmic rays by the solar wind is stressed, as is the relevance of the derived ‘interstellar cosmic ray spectrum’ to the origin of the Galactic particles by way of studies of diffuse cosmic gamma rays.

Turning to the thorny question of solar neutrinos, the present status of the observations is examined, with particular reference to the backgrounds. An analysis is made of the apparent time-variability of the neutrino signal and the relevance of the recently detected neutrino burst from the supernova SN 1987a in the Large Magellanic Cloud. It is concluded that variability is not yet proven; however, the low signal level is still a cause for concern, and may yet require a dramatic explanation such as finite neutrino mass and neutrino oscillation.