Long-duration high-energy proton events observed by GOES in October 1989

A Anttila,L G Kocharov,R Vainio,J Torsti

doi:10.1007/s005850050662

Abstract

We consider the prolonged injection of the high-energy (>10 MeV) protons during the three successive events observed by GOES in October 1989. We apply a solar-rotation-stereoscopy approach to study the injection of the accelerated particles from the CME-driven interplanetary shock waves in order to find out how the effectiveness of the particle acceleration and/or escape depends on the angular distance from the shock axis. We use an empirical model for the proton injection at the shock and a standard model of the interplanetary transport. The model can reproduce rather well the observed intensityâtime profiles of the October 1989 events. The deduced proton injection rate is highest at the nose of the shock; the injection spectrum is always harder near the Sun. The results seem to be consistent with the scheme that the CME-driven interplanetary shock waves accelerate a seed particle population of coronal origin.Key words. Interplanetary physics Â· Energetic particles Â· Solar physics Â· astrophysics and astronomy Â· Flares and mass ejections

Highlights

Three very energetic solar energetic particle (SEP) events were observed during the period of 19±31 October 1989 on board geosynchronous satellites GOES 6 and 7 after X-class solarares that occurred on 19, 22 and 24 October
We study the injection in a wide energy range (GOES and neutron monitor data from $10 MeV to GeV energies) for extended time-periods during the shock passage from the Sun to the Earth's distance
We introduce a dependence of the injection on the longitudinal distance from the shock axis

Summary

Introduction

Three very energetic SEP events were observed during the period of 19±31 October 1989 on board geosynchronous satellites GOES 6 and 7 after X-class solarares that occurred on 19, 22 and 24 October. Sea-level neutron monitors detected exceptionally high intensity increases. This indicated that the particle spectra were extending to a few GeV. In connection with the particle events, coronal mass ejections (CMEs) were detected (Kahler, 1993, 1994). Anttila of coronal/interplanetary shocks, which may have accelerated particles to very high energies well beyond 100 MeV

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