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Semiempirical Models of the Solar Atmosphere. I. The Quiet- and Active Sun Photosphere at Moderate Resolution

Abstract : In this paper we study and modify previous semiempirical models of the solar photosphere as observed at moderate spatial and temporal resolution (3 and 30 minutes, respectively) in the main quiet- and active Sun component features. Our present models are constructed to match the relevant available observations at this resolution for which a one-dimensional and time-independent stratification is reasonable. The models do not describe the fine structure and temporal variability observed in high-resolution images but correspond to a "radiation averaging" over the fine-structure and p-mode variations. We use the observed limb darkening in the range 0.3–2.4 m, as well as the absolute intensities and details of the spectral continua and lines in this range, to validate and adjust the models. Using the method described in a previous paper, we compute the emergent radiation from our models in full detail for the visible and IR continuum and the lines in the interval 0.3–5 m for which we have atomic data from NIST (13,000 lines used) and molecular data from HITRAN and Gray & Corbally (480,000 molecular lines used). The observations, abundances, and atomic/molecular data are improved over previous work and yield models that better fit the observations. In addition, we construct a new penumbra model. The visible and IR detailed spectra computed from these models provide insight for understanding the effects of magnetic fields on the solar irradiance and are useful tools for computing synthetic spectral irradiances in different solar activity configurations.
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J.M. Fontenla, E. Avrett, Gérard Thuillier, J. Harder. Semiempirical Models of the Solar Atmosphere. I. The Quiet- and Active Sun Photosphere at Moderate Resolution. The Astrophysical Journal, American Astronomical Society, 2006, 639, pp.441-458. ⟨10.1086/499345⟩. ⟨hal-00068916⟩



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