Hydrogen Emission in Type II White-light Solar Flares

Abstract

Type II WLFs have weak Balmer line emission and no Balmer jump. We carried out a set of radiative hydrodynamic simulations to understand how the hydrogen radiative losses vary with the electron beam parameters and more specifically with the low energy cutoff. Our results have revealed that for low energy beams, the excess flare Lyman emission diminishes with increasing low energy cutoff as the energy deposited into the top chromosphere is low compared to the energy deposited into the deeper layers. Some Balmer excess emission is always present and is driven primarily by direct heating from the beam with a minor contribution from Lyman continuum backwarming. The absence of Lyman excess emission in electron beam models with high low energy cutoff is a prominent spectral signature of type II WLFs.

7 pages

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Cited by in corpus (6)

• Bridging High-Density, Electron Beam Coronal Transport and Deep Chromospheric Heating in Stellar Flares
• Minute-cadence Observations of the LAMOST Fields with the TMTS: III. Statistic Study of the Flare Stars from the First Two Years
• An approximate recipe of chromospheric radiative losses for solar flares
• Radiative Hydrodynamic Simulations of the Spectral Characteristics of Solar White-light Flares
• Chromospheric Bubbles in Solar Flares
• Evaluation of different recipes for chromospheric radiative losses in solar flares