Space Science Reviews

, 159:263

First online:

Microflares and the Statistics of X-ray Flares

  • I. G. HannahAffiliated withSchool of Physics & Astronomy, University of Glasgow Email author 
  • , H. S. HudsonAffiliated withSpace Sciences Laboratory, University of California at Berkeley
  • , M. BattagliaAffiliated withSchool of Physics & Astronomy, University of Glasgow
  • , S. ChristeAffiliated withNASA Goddard Space Flight Center
  • , J. KašparováAffiliated withAstronomický ústav AV ČR
  • , S. KruckerAffiliated withSpace Sciences Laboratory, University of California at Berkeley
  • , M. R. KunduAffiliated withDept. of Astronomy, Univ. of Maryland
  • , A. VeronigAffiliated withInstitute of Physics/IGAM, University of Graz

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This review surveys the statistics of solar X-ray flares, emphasising the new views that RHESSI has given us of the weaker events (the microflares). The new data reveal that these microflares strongly resemble more energetic events in most respects; they occur solely within active regions and exhibit high-temperature/nonthermal emissions in approximately the same proportion as major events. We discuss the distributions of flare parameters (e.g., peak flux) and how these parameters correlate, for instance via the Neupert effect. We also highlight the systematic biases involved in intercomparing data representing many decades of event magnitude. The intermittency of the flare/microflare occurrence, both in space and in time, argues that these discrete events do not explain general coronal heating, either in active regions or in the quiet Sun.


Sun Flares X-rays