SIMULATIONS OF THE MG II K AND CA II 8542 LINES FROM AN ALFVEN WAVE-HEATED FLARE CHROMOSPHERE

We use radiation hydrodynamic simulations to examine two models of solar flare chromospheric heating: Alfven 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 angstrom 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 angstrom 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.