Spectral Properties and Transport Effects of Suprathermal Heavy Ions in Stream Interaction Regions
Abstract
Ions and electrons with energies above the bulk solar wind ( 2-100's keV/nuc) are known as suprathermal (ST) particles. Previous observations have shown that ST particles are an important constituent of the overall seed population accelerated in interplanetary events. However, observations of these particles have varied greatly which has fueled continual debate over where these populations originate and how they are accelerated. Here we present our findings and contextualize them in terms of current particle acceleration and transport models. In this study we analyze the spectral properties and abundances of 0.02-3.0 MeV nucleon-1 ST H-Fe ions in 41 stream interaction regions (SIRs) near 1 AU observed by Wind and ACE spacecraft from 1995 January through 2008 December. We calculate the event-averaged spectral index and compare with the magnetic compression ratio for each event. We investigate the behavior of the spectral index of O and Fe for systematic steepening or flattening with energy. The ST heavy ion abundance ratio does not exhibit any systematic behavior when plotted against the ion's mass per charge (M/Q), and first ionization potential. These findings pose challenges for a variety of particle acceleration and transport models, and the notion that SIR ST ions originate directly from the bulk solar wind.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSH51C2845F
- Keywords:
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- 7514 Energetic particles;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMYDE: 7526 Magnetic reconnection;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMYDE: 7845 Particle acceleration;
- SPACE PLASMA PHYSICSDE: 7859 Transport processes;
- SPACE PLASMA PHYSICS