Photospheric dynamics and the NLTE formation of the solar K I 769.9 NM line
Abstract
Earlier analyses of the K I 769.9 nm resonance line are extended as a diagnostic of dynamical phenomena in the solar photosphere by evaluating the effects of dynamical variations on departures from LTE in the K I spectrum. Representative models for the solar granulation and the solar fiveminute oscillation are used to estimate dynamical NLTE departures in the K I populations and to compare these to standarad planeparallel NLTE modeling. Various NLTE mechanisms operate together in K I simultaneously with fortuitous cancellations; the resulting population departures vary less than 30 percent between dynamical perturbations. These results validate the assumption of departure invariance, i.e., adopting NLTE population departure coefficients from a standard static model for use in dynamical perturbations, as a good firstorder approximation in K I 769.9 nm formation studies.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 April 1991
 Bibcode:
 1991A&A...244..501G
 Keywords:

 K Lines;
 Local Thermodynamic Equilibrium;
 Nonequilibrium Thermodynamics;
 Photosphere;
 Solar Atmosphere;
 Solar Spectra;
 Radiative Transfer;
 Resonance Lines;
 Solar Granulation;
 Solar Oscillations;
 Solar Physics