Cloud model with variable source function for solar Hα structures.
Abstract
The "cloud model" used to derive the physical parameters of solar chromospheric features is extended to the cases of non-constant source function and of velocity gradients. This model assumes a given relationship between the source function and the opacity of the cloud which is derived from non-LTE modelling. An algorithm using 4 points of the Halpha_ profile is proposed to derive the optical thickness, the line-of-sight velocity and the dopplerwidth. The results are compared with a 5-points inversion which does not use the given relationship between source function and opacity. Effects of the uncertainty about the radiation coming from the underlying chromosphere, as well as effects of data noise, are discussed. The inversion method is illustrated by some examples of observed profiles obtained with the MSDP spectrograph of the VTT telescope (Teide Observatory).
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 1996
- Bibcode:
- 1996A&A...309..275M
- Keywords:
-
- SUN: CHROMOSPHERE;
- LINE: PROFILES;
- RADIATIVE TRANSFER;
- SUN: FILAMENTS