Search

Start Over Subject solar chromosphere

2. The Lyman α line in the solar chromosphere: penetrative model and approximations

Creator:
Faurobert, M., Frisch, H., and Skumanich, A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
solar chromosphere, Lyman α line, and energy balance
Language:
Czech
Description:
A multi-level calculation of the hydrogen spcctrum by Skumanich and Lites, followed by a two-level rcpresentation of each transition, shows that all the solar Lyman α photons are created in the high chromosphere, above ro^ ≃ 10^2 (ro denote the optical depth at the center of the line). Below this depth the Lyman α line is only fed by multiple scatterings. The source function decreases, first very slowly and then as ro^ ≃ 10^7. The change in slope occurs at ro^ ≃ 10^5. We shall present a model for the formation of Lyman α in the chromosphere below the creation region. The hydrogen atom is treated as a two-level atom and the chromosphere as a semi-infinite medium free of primary sources and illuminated by an isotropic and frequency independent radiation field at ro^ ≃ 10^2. A second order escape probability approximation fields a simple analytical expression which accurately reproduces the behaviour of the Lyman α source function between ro ≃ 10^2 and 5 10^6 provided the destruction probability is set close to 10“-6. This value agrees very well with that obtained by Skumanich and Lites for the generalized Lyman α destruction probability in the low chromosphere.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

Limit your search