Simulations of the Mg II k and Ca II 8542 lines from an AlfvÉn Wave-heated Flare Chromosphere

Graham S. Kerr, Lyndsay Fletcher, Alexander J B Russell, Joel C. Allred

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73 Citations (Scopus)
213 Downloads (Pure)


We use radiation hydrodynamic simulations to examine two models of solar flare chromospheric heating: Alfvén wave dissipation and electron beam collisional losses. Both mechanisms are capable of strong chromospheric heating, and we show that the distinctive atmospheric evolution in the mid-to-upper chromosphere results in Mg ii k-line emission that should be observably different between wave-heated and beam-heated simulations. We also present Ca ii 8542 Å profiles that are formed slightly deeper in the chromosphere. The Mg ii k-line profiles from our wave-heated simulation are quite different from those from a beam-heated model and are more consistent with Interface Region Imaging Spectrograph observations. The predicted differences between the Ca ii 8542 Å in the two models are small. We conclude that careful observational and theoretical study of lines formed in the mid-to-upper chromosphere holds genuine promise for distinguishing between competing models for chromospheric heating in flares.

Original languageEnglish
Article number101
Pages (from-to)1-16
Number of pages16
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 11 Aug 2016


  • methods: numerical
  • Sun: atmosphere
  • Sun: chromosphere
  • Sun: flares
  • Sun: UV radiation
  • waves

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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