Open AccessO i line emission in cool stars: calculations using partial redistribution
Author(s) -
Koncewicz R.,
Jordan C.
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.11130.x
Subject(s) - physics , stars , opacity , radiative transfer , astrophysics , scattering , excited state , stellar atmosphere , atomic physics , spectral line , resonance (particle physics) , line (geometry) , redistribution (election) , photon , astronomy , optics , geometry , mathematics , politics , law , political science
Radiative transfer calculations have been performed for five cool stars: α Tau, β Gem, Procyon, ε Eri and the Sun, for the purpose of investigating the behaviour of the O i emission over a wide range of stellar types, and its dependence on coherent photon scattering. These stars span a range of spectral types from F5 iv – v to K5 iii and surface gravities 1.25 < log g * < 4.75 . Particular attention has been paid to the calculation of the flux in the resonance triplet around 1305 Å which is pumped by H Lyβ, including the effects of partial redistribution (PRD) and cross‐redistribution of photons. These are the first calculations for the resonance triplet in giant stars using a full PRD treatment. Calculations of the predominantly collisionally excited intersystem doublet at 1355, 1358 Å are included, and it is found that the ratio of these fluxes shows the effects of opacity. The flux in the forbidden line at 1641 Å is calculated for the giant stars and the effects of coherent scattering on this line are investigated. The discrepancy between the calculated and observed fluxes in the O i lines is used to infer the inadequacy of single‐component chromospheric models.