http://arxiv.org/abs/1901.04369
Hydrogen has been almost completely ignored in studies of the abundance patterns of the chemical elements in solar energetic particles (SEPs). We seek to find impulsive events where H fits these abundance patterns and document the events that do not, suggesting possible reasons for the disparity. For 24% of the smaller impulsive SEP events, the relative abundance of H fits within one standard deviation of the power-law fit of the abundances of elements 5 < Z < 57, relative to coronal abundances; 64% of events are within two standard deviations of this value. In impulsive events with high intensities, H can be 10 to 100 times its expected value. In some of these larger events, increased scattering at high wave number may preferentially detain H, perhaps with self-amplified waves. In most large impulsive SEP events, however, associated shock waves may play a greater role than previously thought, contributing to 45% of impulsive events. Shocks may sample protons from the ambient coronal plasma or residual background as well as re-accelerating heavier impulsive SEP ions injected from the region of magnetic reconnection in solar jets. Excess H may be a signature of shock acceleration.
D. Reames
Tue, 15 Jan 19
51/83
Comments: 21 pages, 9 figures, submitted to Solar Physics
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