Temperature in Solar Sources of 3He-rich Solar Energetic Particles and Relation to Ion Abundances

Abstract

3He-rich solar energetic particles (SEPs) are believed to be accelerated in solar flares or jets by a mechanism that depends on the ion charge-to-mass (Q/M) ratio. It implies that the flare plasma characteristics (e.g., temperature) may be effective in determining the elemental abundances of 3He-rich SEPs. This study examines the relation between the suprathermal (<0.2 MeV/nuc) abundances of the He-Fe ions measured on the Advanced Composition Explorer and temperature in the solar sources for 24 3He-rich SEP events in the period 2010-2015. The differential emission measure technique is applied to derive the temperature of the source regions from the extreme ultraviolet imaging observations on the Solar Dynamics Observatory. The obtained temperature distribution peaks at 2.0-2.5 MK that is surprisingly consistent with earlier findings based on in-situ elemental abundance or charge state measurements. We have found a significant anti-correlation between 3He/4He ratio and solar source temperature with a coefficient -0.6. It is most likely caused by non-charge-stripping processes, as both isotopes would be fully ionized in the inferred temperature range. This study shows that the elemental ratios 4He/O, N/O, Ne/O, Si/O, S/O, Ca/O, Fe/O generally behave with temperature as expected from abundance enhancement calculations at ionization equilibrium. The C and Mg, the two species with small changes in the Q/M ratio in the obtained temperature range, show no such behavior with temperature and could be influenced by similar processes as for the 3He/4He ratio.

arXiv commentaccepted for publication in ApJ

References in corpus (23)

• Ionization balance for optically thin plasmas: rate coefficients for all atoms and ions of the elements H to Ni
• The Two Sources of Solar Energetic Particles
• Thermal Diagnostics with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory: A Validated Method for Differential Emission Measure Inversions
• Multi-scale Gaussian normalization for solar image processing
• CHIANTI - an atomic database for emission lines - Paper XV: Version 9, improvements for the X-ray satellite lines
• Stochastic Acceleration of ${}^3$He and ${}^4$He in Solar Flares by Parallel Propagating Plasma Waves: General Results
• Abundance Enhancements in Impulsive Solar Energetic-Particle Events with Associated Coronal Mass Ejections
• Multiwavelength study of twenty jets emanating from the periphery of active regions
• 3He-rich solar energetic particles: Solar sources
• Multi-Spacecraft Observations of Recurrent 3He-Rich Solar Energetic Particles
• Abundances, Ionization States, Temperatures, and FIP in Solar Energetic Particles
• 3He-Rich Solar Energetic Particles in Helical Jets on the Sun
• Observations of solar X-ray and EUV jets and their related phenomena
• Variations in Abundance Enhancements in Impulsive Solar Energetic-Particle Events and Related CMEs and Flares
• The injection of ten electron/${}^3$He-rich SEP events
• 3He-Rich Solar Energetic Particles from Sunspot Jets
• Case studies of multi-day 3He-rich solar energetic particle periods
• Temperature of the Source Plasma for Impulsive Solar Energetic Particles
• Flare-associated type III radio bursts and dynamics of the EUV jet from SDO/AIA and RHESSI observations
• Association of 3He-Rich Solar Energetic Particles with Large-Scale Coronal Waves
• Preferential Heating and Acceleration of Heavy Ions in Impulsive Solar Flares
• Heating of Heavy Ions in Low-beta Compressible Turbulence
• Element Abundances of Solar Energetic Particles and the Photosphere, the Corona, and the Solar Wind

Cited by in corpus (13)

• Sixty Years of Element Abundance Measurements in Solar Energetic Particles
• Fifty Years of 3He-rich Events
• Solar Energetic Particles: Spatial Extent and Implications of the H and He Abundances
• Energy Spectra vs. Element Abundances in Solar Energetic Particles and the Roles of Magnetic Reconnection and Shock Acceleration
• Solar Energetic Particle Charge States and Abundances with Nonthermal Electrons
• Element Abundances in Impulsive Solar Energetic Particle Events
• Preferential acceleration of heavy ions in magnetic reconnection: Hybrid-kinetic simulations with electron inertia
• Signature and escape of highly fractionated plasma in an active region
• Seeds and Sequences of Element Abundances in Solar Energetic Particle Events
• Variable Ion Compositions of Solar Energetic Particle Events in the Inner Heliosphere: A Field-line Braiding Model with Compound Injections
• Origin of Unusual Composition of 3He-Rich Solar Energetic Particles
• Solar Particle Acceleration
• A Perspective on Solar Energetic Particles