Spatial Distribution of Element Abundances and Ionization States in Solar Energetic-Particle Events

Spatial Distribution of Element Abundances and Ionization States in Solar Energetic-Particle Events We have studied the spatial and temporal distribution of abundances of chemical elements in large “gradual” solar energetic-particle (SEP) events, and especially the source plasma temperatures, derived from those abundances, using measurements from the Wind and Solar TErrestrial RElations Observatory (STEREO) spacecraft, widely separated in solar longitude. A power-law relationship between abundance enhancements and mass-to-charge ratios [ A / Q $A/Q$ ] of the ions can be used to determine Q $Q$ -values and source plasma temperatures at remote spacecraft with instruments that were not designed for charge-state measurements. We search for possible source variations along the accelerating shock wave, finding one clear case where the accelerating shock wave appears to dispatch ions from 3.2 ± 0.8 MK $3.2\pm 0.8~\mbox{MK}$ plasma toward one spacecraft and those from 1.6 ± 0.2 MK $1.6\pm 0.2~\mbox{MK}$ plasma toward another, 116∘ away. The difference persists for three days and then fades away. Three other SEP events show less-extreme variation in source temperatures at different spacecraft, in one case observed over 222∘ in longitude. This initial study shows how the power-law relation between abundance enhancements and ion A / Q $A/Q$ -values provides a new technique to determine Q $Q$ and plasma temperatures in the seed population of SEP ions over a broad region of space using remote spacecraft with instruments that were not originally designed for measurements of ionization states. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Solar Physics Springer Journals

Spatial Distribution of Element Abundances and Ionization States in Solar Energetic-Particle Events

Solar Physics , Volume 292 (8) – Aug 11, 2017

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Publisher
Springer Netherlands
Copyright
Copyright © 2017 by Springer Science+Business Media B.V.
Subject
Physics; Astrophysics and Astroparticles; Atmospheric Sciences; Space Sciences (including Extraterrestrial Physics, Space Exploration and Astronautics)
ISSN
0038-0938
eISSN
1573-093X
D.O.I.
10.1007/s11207-017-1138-8
Publisher site
See Article on Publisher Site

Abstract

We have studied the spatial and temporal distribution of abundances of chemical elements in large “gradual” solar energetic-particle (SEP) events, and especially the source plasma temperatures, derived from those abundances, using measurements from the Wind and Solar TErrestrial RElations Observatory (STEREO) spacecraft, widely separated in solar longitude. A power-law relationship between abundance enhancements and mass-to-charge ratios [ A / Q $A/Q$ ] of the ions can be used to determine Q $Q$ -values and source plasma temperatures at remote spacecraft with instruments that were not designed for charge-state measurements. We search for possible source variations along the accelerating shock wave, finding one clear case where the accelerating shock wave appears to dispatch ions from 3.2 ± 0.8 MK $3.2\pm 0.8~\mbox{MK}$ plasma toward one spacecraft and those from 1.6 ± 0.2 MK $1.6\pm 0.2~\mbox{MK}$ plasma toward another, 116∘ away. The difference persists for three days and then fades away. Three other SEP events show less-extreme variation in source temperatures at different spacecraft, in one case observed over 222∘ in longitude. This initial study shows how the power-law relation between abundance enhancements and ion A / Q $A/Q$ -values provides a new technique to determine Q $Q$ and plasma temperatures in the seed population of SEP ions over a broad region of space using remote spacecraft with instruments that were not originally designed for measurements of ionization states.

Journal

Solar PhysicsSpringer Journals

Published: Aug 11, 2017

References

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