Passive longitudes of solar cosmic ray sources

Abstract

Solar proton events during the period from 1956 to 2012 are considered. Fluences of protons of various energies in these events are computed. On the basis of these data, the inhomogeneity observed in our earlier studies of the distribution of their sources on the Sun along the Carrington longitude is confirmed. Special attention is given to the extensive interval of passive longitudes discovered between ≈90°–170° over the period of observations. The summed proton fluence of the events whose sources lie in this interval of Carrington longitudes is considerably lower than the summed proton fluences of events in other heliolongitude intervals. Of the 60 most powerful solar proton events observed during the period of observations, no more than 1 event originated from this interval of passive longitudes.