Chromospheric downflow velocities as a diagnostic in solar flares
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We explore the dynamics of chromospheric condensations driven by evaporation during the impulsive phase of solar flares. Specifically, we find that the maximum chromospheric downflow speed obeys the approximate relation υd= 0.4 (F/ϱch)1/3, where F is that part of the flare energy flux driving chromospheric evaporation, and ϱch is the mass density in the preflare chromosphere just below the preflare transition region. This implies that chromospheric downflows as measured by Hα asymmetries may be a powerful probe of flare energetics.
KeywordsEvaporation Flare Transition Region Mass Density Energy Flux
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