O i line emission in cool stars: calculations using partial redistribution |
| |
| Authors: | R Koncewicz C Jordan |
| |
| Institution: | Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP |
| |
| Abstract: | 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. |
| |
| Keywords: | line: formation radiative transfer stars: chromospheres |
|
|
