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Author name code: botnen
ADS astronomy entries on 2022-09-14
author:"Botnen, A.V."
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Title: Multi-level 3D non-LTE computations of lithium lines in the
metal-poor halo stars HD 140283 and HD 84937
Authors: Asplund, M.; Carlsson, M.; Botnen, A. V.
2003A&A...399L..31A Altcode: 2003astro.ph..2406A
The lithium abundances in metal-poor halo stars are of importance
for cosmology, galaxy evolution and stellar structure. In an attempt
to study possible systematic errors in the derived Li abundances,
the line formation of Li I lines has been investigated by means of
realistic 3D hydrodynamical model atmospheres of halo stars and
3D non-LTE radiative transfer calculations. These are the first
detailed 3D non-LTE computations reported employing a multi-level
atomic model showing that such problems are now computationally
tractable. The detailed computations reveal that the Li I population
has a strong influence from the radiation field rather than the local
gas temperature, indicating that the low derived Li abundances found by
Asplund et al. (\cite{Asplund1999}) are an artifact of their assumption
of LTE. Relative to 3D LTE, the detailed calculations show pronounced
over-ionization. In terms of abundances the 3D non-LTE values are
within 0.05 dex of the 1D non-LTE results for the particular cases of
HD 140283 and HD 84937, which is a consequence of the dominance of the
radiation in determining the population density of Li I. Although 3D
non-LTE can be expected to give results rather close (~+/- 0.1 dex)
to 1D non-LTE for this reason, there may be systematic trends with
metallicity and effective temperature.
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Title: Multi3D, 3D Non-LTE Radiative Transfer
Authors: Botnen, A.; Carlsson, M.
1999ASSL..240..379B Altcode: 1999numa.conf..379B
No abstract at ADS
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Title: Radiative transfer in 3D
Authors: Botnen, A.
1997MsT..........2B Altcode:
No abstract at ADS