Open AccessCharge States of Solar Energetic Iron: Nonequilibrium Calculation with Shock-induced Acceleration
Author(s) -
A. F. Barghouty,
R. A. Mewaldt
Publication year - 1999
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/312163
Subject(s) - physics , charge (physics) , ion , solar energetic particles , particle acceleration , atomic physics , astrophysics , nucleon , solar wind , acceleration , non equilibrium thermodynamics , shock (circulatory) , feature (linguistics) , particle (ecology) , computational physics , nuclear physics , plasma , coronal mass ejection , classical mechanics , quantum mechanics , oceanography , medicine , geology , linguistics , philosophy
Observed charge states of solar energetic ions by Solar, Anomalous, and Magnetospheric Particle Explorer and Advanced Composition Explorer from recent large solar events in 1992 and 1997 show an energy-dependent feature that apparently has not been seen in earlier events, e.g., in 1978–1979. The mean charge state of iron, and to a lesser extent other heavy ions, was observed to increase with energy from ∼0.5 to ∼50 MeV nucleon^(-1). We present a possible explanation for this new feature and discuss potential implications for models of particle acceleration. Our calculation suggests that this energy-dependent feature is a result of the charge-changing and energy-changing processes taking place concurrently and can be absent when the processes act over different timescales.
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