Solar and heliospheric sources of suprathermal and energetic particle populations

Abstract

Objectives and some preliminary findings of an ongoing international team project carried out at ISSI, Bern will be presented. Suprathermal and energetic particle s in interplanetary space have a multitude of origins, i.e. acceleration and propagation hi stories. Solar flares, coronal mass ejections (CMEs), co-rotating interaction regions (CIRs), the heliospheric termination shock, planetary bow shocks and magnetospheres have all been recognized as energetic particle sources. Less energetic (suprathermal) particles of solar origin and pick-up ions have also a vital role both in their own right and as seeds of energetic particles accelerated in interplanetary disturbances. The relative contributions of various particle populations vary with energy and with the phase of the solar cycle. Particular attention will be given in our project to quiet periods and to large events. While quiet-time fluxes are expected to shed light on some base-line features of coronal and interplanetary acceleration processes, relatively large events dominate bot h the long-term fluence levels and the statistical properties of cumulative fluence plots. The importance of energetic and suprathermal particles that mostly cannot escape into interplanetary space, but contribute to co ronal heating and possibly also to solar wind composition, will also be discussed. B. Sripathi Acharya, Sunil Gupta, P. Jagadeesan, Atul Jain, S. Karthikeyan, Samuel Morris, and Suresh Tonwar

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