A Study on the Fine Structure of a Quiet Solar Chromospheric Region Near the Disk Center
Abstract
In this study, the morphological and physical properties of fine structures of a quiet chromospheric region were studied on CCD images and the dynamical characteristics of the investigated region were identified.
The observations were obtained with the Vacuum Tower Telescope in Tenerife, Canary Islands and the Dunn Solar Telescope at the National Solar Observatory, New Mexico, USA. During the observations, time series of high spatial, spectral and temporal resolution images were taken by scanning the Halpha profile at different wavelength steps of narrow bandpasses. Intensity and Doppler images at the line center and the wing of Halpha were derived by using the standard Doppler-shift and Lambdameter methods. Then these images were used to distinguish variations on the morphology and velocity of fine structures with the height and time. The cloud model, which has been used extensively in the analysis of Hα contrast profiles was applied to the observations to derive the physical parameters such as the source function, optical depth at the line center, Doppler width and the line of sight velocity of the investigated fine structures. In order to determine physical conditions in these structures, the values of cloud model parameters were used together to derive other parameters such as the number density of hydrogen atoms at levels 1 and 2, total particle density, electron density, temperature, gas pressure, mass density. Finally, global properties of chromospheric features and time evolution of their physical parameters were discussed in detail and then compared with results obtained by various authors. It is concluded that the dark and the bright mottles observed at the network boundaries on the disk have a similar nature and that they also have similar physical properties with the spicules observed at the limb.- Publication:
-
Ph.D. Thesis
- Pub Date:
- January 2009
- Bibcode:
- 2009PhDT.........1B
- Keywords:
-
- Sun;
- Chromosphere;
- fine structure