Change of physical properties in developing chromospheric plages.
Abstract
Spectra of about 300 plage knots obtained at different stages of plage development are used to construct Ca II H-line contours and to determine the residual-central-intensity ratio of the Ca II H and H-alpha lines. These ratios and line contours are compared with the respective theoretical values given by a large number of models involving pressure and temperature variations with depth. The line contours are computed by simultaneously solving the equations of radiative transfer and statistical equilibrium for incoherent scattering. A sequence of models corresponding to plages of increasing brightness is chosen, physical parameters are determined on the basis of these models as well as plage observations, and it is concluded that a plage is a compressed layer located at a height of 1700 km. Logarithmic hydrogen densities in the range from 10.7 to 12.6 are determined for individual knots, and these knots are found to be up to 2000 K hotter than the ambient chromosphere.
- Publication:
-
Izvestiya Ordena Trudovogo Krasnogo Znameni Krymskoj Astrofizicheskoj Observatorii
- Pub Date:
- 1976
- Bibcode:
- 1976IzKry..55...14B
- Keywords:
-
- Chromosphere;
- Faculae;
- H Lines;
- Solar Spectra;
- Atmospheric Models;
- Calcium;
- H Alpha Line;
- Hydrogen Plasma;
- Plasma Density;
- Vertical Motion;
- Solar Physics