Solar-terrestrial response to large extension or long-duration solar gamma ray events

Abstract

Gamma ray lines (GRL) from the large event of 29 September 1989 were observed from a site about 25 degrees from the flare site. In June 1991, at least three long-duration GRL events were observed by several spacecraft. None of the models put forward to explain these events are convincing. We discuss the plasma and particle data at Earth ́s orbit for these two types of events and we propose that some perturbations in interplanetary space may originate in the solar chromosphere outside active regions.