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Modeling the Formation of Hα Line in Solar Chromosphere: Non-LTE Simulation Findings

Detailed study using Radiation-MHD simulation for Hα line formation in solar chromosphere. Analysis of statistical equilibrium and non-equilibrium ionization of hydrogen. Results show correlation between Hα core intensity and formation height. Simulation closely matches observations without microturbulence. Key aspects include 3D radiative transfer, gas temperature measure via line-core width, and fibril-like structure. Utilizes RADYN code and equations for conservation of mass, momentum, and energy. Includes ionization balance and equation of state.

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Modeling the Formation of Hα Line in Solar Chromosphere: Non-LTE Simulation Findings

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  1. non-LTEゼミ論文紹介「The formation of the Hα line in the solar chromosphere」① 20120307 T. Anan

  2. abstruct • Radiation-MHD simulation + 3D non-LTE radiative transfer computation => Hα • Statistical equilibrium • Complete frequency redistribution • Non-equilibrium ionization of hydrogen • We find • 3D radiative transfer is essential in modeling Hα • Hα opacity is mainly sensitive mass density • Hα core intensity is correlated with the average formation height • The line-core width is a measure of the gas temperature • Fibril-like structure • Formation height • Simulated results are very similar to observed one without the need for additional microturbilance

  3. RADYN code • Hydrodynamics • Carlsson & Stein 1992, 1995, 1997, & 2002 • Eq. of conservation of mass, momentum, and energy • Non-LTE radiative transfer problem including non-equilibrium rate equations • Ionization balance • Equation of state • Partial redistribution of photons in the Ryman lines • Elements & levels • H I (5 levels + continuum) • Ca II (5 levels + continuum) • He I (5 levels + continuum) • He II (3 levels + continuum) • He III (1 levels + continuum) • Lower boundary is just below the photosphere (τ500nm = 16) • Velocity field derived from MDI (Doppler shift, 676.78 nm, Ni I, quiet region) • Upper boundary is corona at 10000 km above the lower boundary • Run for more than 1 hour of solar time, and saved output at 10 s intervals => 374 sapshots

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