Partial redistribution in multilevel atoms. I. Method and application to the solar hydrogen line formation

I. Hubeny, B. W. Lites

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

We present a robust method for solution of multilevel non-LTE line transfer problems including the effects of partial frequency redistribution (PRD). This method allows the self-consistent solution for redistribution of scattered line photons simultaneously in multiple transitions of a model atom, including the effects of resonant Raman scattering ("cross-redistribution") among lines sharing common upper levels. The method is incorporated into the framework of the widely used non-LTE complete redistribution code MULTI. We have applied this method to the problem of transfer in hydrogen lines in a plane-parallel solar model atmosphere, including cross-redistribution between the Hα and Lβ, using general redistribution functions for the Lα and Lβ lines which are not restricted by the impact approximation. The convergence properties of this method are demonstrated to be comparable to that of the equivalent complete redistribution problem. In this solar model, PRD in the Lα line produces the dominant influence on the level populations. It changes considerably the populations of the excited states of hydrogen, as well as the proton number density, in the middle and upper chromosphere, owing to modification of the Lα wing radiation. The population of the hydrogen ground state undergoes only modest changes, however. The influence of cross-redistribution and PRD in Lβ has a much smaller influence on the level populations but a considerable influence on the wing intensity of the Lβ line.

Original languageEnglish (US)
Pages (from-to)376-388
Number of pages13
JournalAstrophysical Journal
Volume455
Issue number1
DOIs
StatePublished - Dec 10 1995

Keywords

  • Atomic processes
  • Line: formation
  • Radiative transfer
  • Sun: chromosphere

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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