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

Title:

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

Creator:

Faurobert, M., Frisch, H., and Skumanich, A.

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:b42ed3b6-85e6-43b2-8369-277f20b93c01
uuid:b42ed3b6-85e6-43b2-8369-277f20b93c01

Subject:

solar chromosphere, Lyman α line, and energy balance

Type:

model:article and TEXT

Format:

bez média and svazek

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.

Language:

Czech

Rights:

http://creativecommons.org/publicdomain/mark/1.0/
policy:public

Coverage:

205-209

Source:

Publications of the Astronomical Institute of the Academy of Sciences of the Czech Republic | 1987 Volume:63-70 | Number:66

Harvested from:

CDK

Metadata only:

false