Work

Large gradual solar energetic particle events

Year: 2016

Type: review

Abstract: Solar energetic particles, or SEPs, from suprathermal (few keV) up to relativistic ( $$\sim $$ few GeV) energies are accelerated near the Sun in at least two ways: (1) by magnetic reconnection-driven processes during solar flares resulting in impulsive SEPs, and (2) at fast coronal-mass-ejection-driven shock waves that produce large gradual SEP events. Large gradual SEP events are of particular interest because the accompanying high-energy ( $${>}10$$ s MeV) protons pose serious radiation threats to human explorers living and working beyond low-Earth orbit and to technological assets such as communications and scientific satellites in space. However, a complete understanding of these large SEP events has eluded us primarily because their properties, as observed in Earth orbit, are smeared due to mixing and contributions from many important physical effects. This paper provides a comprehensive review of the current state of knowledge of these important phenomena, and summarizes some of the key questions that will be addressed by two upcoming missions—NASA’s Solar Probe Plus and ESA’s Solar Orbiter. Both of these missions are designed to directly and repeatedly sample the near-Sun environments where interplanetary scattering and transport effects are significantly reduced, allowing us to discriminate between different acceleration sites and mechanisms and to isolate the contributions of numerous physical processes occurring during large SEP events.

Source: Living Reviews in Solar Physics

DOI: 10.1007/s41116-016-0002-5

Authors: Mihir Desai, Joe Giacalone

Institutions: Southwest Research Institute, University of Arizona

Language: English

Topic: Solar and Space Plasma Dynamics

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: diamond

Funders: National Science Foundation, National Aeronautics and Space Administration

Awards: THE 3-D CORONAL-SOLAR WIND ENERGETIC PARTICLE ACCELERATION (C-SWEPA) MODULES PROVIDE TOOLS FOR TAKING THE CRITICAL NEXT STEP IN UNDERSTANDING SOLAR E, FAST CORONAL MASS EJECTIONS OR CMES ARE BELIEVED TO DRIVE STRONG SHOCK WAVES THROUGH THE CORONA AND THE INTERPLANETARY MEDIUM AND PRODUCE BOTH, THE L, WE PROPOSE TO USE ANALYTIC THEORY AND ADVANCED NUMERICAL MODELING TO STUDY THE ORIGIN OF HIGH-ENERGY CHARGED PARTICLES IN THE HELIOSPHERE, AND PARTIC, THE OBJECTIVE OF THIS WORK IS TO PROVIDE THE JOHNS JOPKINS APPLIED PHYSICS LABORATORY SUPPORT IN PROCESSING, DISTRIBUTING, AND ANALYZING THE STREAM O