New Insights into White-Light Flare Emission from Radiative-Hydrodynamic Modeling of a Chromospheric Condensation

摘要: (abridged) The heating mechanism at high densities during M dwarf flares is poorly understood. Spectra of in the optical and near-ultraviolet wavelength regimes have revealed three continuum components impulsive phase: 1) an energetically dominant blackbody component with a color temperature T $\sim$ 10,000 K blue-optical, 2) smaller amount Balmer emission lambda $<$ 3646 Angstroms 3) apparent pseudo-continuum blended high-order lines. These properties are not reproduced by models that employ typical "solar-type" flare level nonthermal electrons, therefore our understanding these spectra limited to phenomenological interpretation. We present new 1D radiative-hydrodynamic model from precipitating electrons large energy flux $10^{13}$ erg cm$^{-2}$ s$^{-1}$. simulation produces bright dense, hot chromospheric condensation. For first time, observed jump ratio produced self-consistently model. find blackbody-like small result optically thick Paschen recombination radiation, thus spectrum caused blue light escaping over larger physical depth range compared red light. To previously attributed overlapping lines, we include extra opacity Landau-Zener transitions merged, order levels hydrogen partially ionized atmosphere. This reveals diagnostic ambient charge density densest regions atmosphere heated dMe solar flares.