The longitudinal transport of energetic ions from impulsive solar flares in interplanetary space

J. Giacalone, J. R. Jokipii

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

We present a study of the longitudinal spread of energetic charged particles from a localized instantaneous compact source on the Sun. Our study utilizes a diffusive-transport model for the propagation of energetic ions in interplanetary space. We show that even for very small values of the ratio of perpendicular to parallel diffusion coefficients - a few percent - the particles spread significantly in longitude. Spatial diffusion and adiabatic energy loss of ions in the interplanetary plasma cause impulsive particle events at Earth's orbit to last a few days. In this time, the combination of transport both along and across the local Parker-spiral magnetic field and the longitudinal motion of the magnetic lines of forces rooted at the Sun as it rotates leads to substantial longitudinal transport of the particles. We show that spacecraft separated by as much as 180° or more may observe events associated with compact solar sources, such as those from impulsive solar flares. Our results are qualitatively consistent with recent multi-spacecraft observations.

Original languageEnglish (US)
Article numberL33
JournalAstrophysical Journal Letters
Volume751
Issue number2
DOIs
StatePublished - Jun 1 2012

Keywords

  • Sun: flares
  • Sun: heliosphere
  • diffusion
  • scattering

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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