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Bandwidth Requirements in Spectral Line Transfer Calculations

Published online by Cambridge University Press:  08 February 2017

R. Grant Athay
R. Grant Athay*
Affiliation:
High Altitude Observatory, National Center for Atmospheric Research, Boulder, Colorado

Abstract

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Accurate evaluation of a line source function, S, requires that the frequency bandwidth be sufficiently large to include properly transfer effects in the line wings. The bandwidth required to achieve a given level of accuracy in the evaluation of S can be specified, in units of the Doppler width, in terms of three parameters: the ratio of continuum to line opacity, ro, the probability for collisional deexcitation, ε, and the Voigt wing parameter . Bandwidths required to give S to an accuracy of 2 percent are given for values of ε and ro from 10-2 to 10-8 and for values of from 10-2 to 10-5.

Keywords

line source functiobandwidth requirements
Type
Part B. Theoretical Methods for Handling Non-LTE Problems
Information
International Astronomical Union Colloquium , Volume 2: Spectrum Formation in Stars With Steady-State Extended Atmospheres , August 1970 , pp. 179 - 188
Copyright
Copyright © 1970

References

Athay, R. G., and Skumanich, A. 1967, Ann. d'Ap., 30, 669.Google Scholar