Non‐LTE Line Formation for Hydrogen Revisited | Zendy

N. Przybilla | Zendy; K. Butler | Zendy

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Non‐LTE Line Formation for Hydrogen Revisited

Author(s) -

N. Przybilla,

K. Butler

Publication year - 2004

Publication title -

the astrophysical journal

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 2.376

H-Index - 489

eISSN - 1538-4357

pISSN - 0004-637X

DOI - 10.1086/421316

Subject(s) - balmer series , line (geometry) , hydrogen spectral series , spectral line , physics , excitation , ab initio , hydrogen , range (aeronautics) , ab initio quantum chemistry methods , series (stratigraphy) , computational physics , atomic physics , stars , electron , statistical physics , astrophysics , quantum mechanics , emission spectrum , ionization , ion , mathematics , materials science , molecule , paleontology , geometry , composite material , biology , rydberg formula

We discuss aspects of non-LTE line formation for hydrogen in early-typestars. We evaluate the effect of variations in the electron-impact excitationcross sections in model atoms of differing complexity by comparison withobservation. While the Balmer lines are basically unaffected by the choice ofatomic data, the Paschen, Brackett and Pfund series members allow us todiscriminate between the different models. Non-LTE calculations based on thewidely-used approximation formulae of Mihalas, Heasley & Auer and of Johnsonfail to simultaneously reproduce the optical and IR spectra over the entireparameter range. The use of data from ab-initio calculations up to principalquantum number n<=7 largely solves the problem. We recommend a reference modelusing the available data. This model is of general interest because of theubiquity of the hydrogen spectrum.Comment: 34 pages, 14 figures, 4 table

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