A magnetic reconnection mechanism for ion acceleration and abundance enhancements in impulsive flares

J. F. Drake, P. A. Cassak, M. A. Shay, M. Swisdak, E. Quataert

Research output: Contribution to journalArticle

94 Scopus citations

Abstract

The acceleration of ions during magnetic reconnection in solar flares is explored with simulations and analytic analysis. Ions crossing into Alfvénic reconnection outflows can behave like pickup particles and gain an effective thermal velocity equal to the Alfvén speed. However, with a sufficiently strong ambient out-of-plane magnetic field, which is the relevant configuration for flares, the ions can become adiabatic and their heating is then dramatically reduced. The threshold for nonadiabatic behavior, where ions are strongly heated, becomes a condition on the ion mass-to-charge ratio, m i/mpZi > 10√β0x/2/ π, where mi and Zi are the ion mass and charge state, m p is the proton mass, and β 0x = 8πnT/B 20x is the ratio of the plasma pressure to that of the reconnecting magnetic field B0x. Thus, during flares high mass-to-charge particles gain energy more easily than protons and a simple model reveals that their abundances are enhanced, which is consistent with observations.

Original languageEnglish (US)
Pages (from-to)L16-L20
JournalAstrophysical Journal
Volume700
Issue number1 PART 2
DOIs
StatePublished - 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Acceleration of particles
  • Solar wind
  • Sun: corona
  • Sun: flares

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