Issue |
A&A
Volume 442, Number 2, November I 2005
|
|
---|---|---|
Page(s) | 643 - 650 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361:20053363 | |
Published online | 07 October 2005 |
Effects of line-blocking on the non-LTE Fe I spectral line formation
1
Department of Astronomy and Space Physics, Uppsala University, Box 515, 751 20 Uppsala, Sweden e-mail: remo@astro.uu.se
2
Research School of Astronomy & Astrophysics, Mount Stromlo Observatory, Cotter Road, Weston ACT 2611, Australia
3
Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France
Received:
4
May
2005
Accepted:
11
July
2005
The effects of background line opacity (line-blocking) in
statistical equilibrium calculations for in late-type stellar
atmospheres have been investigated using an extensive and
up-to-date model atom with radiative data primarily from the iron Project.
The background metal line opacities have been computed
using data from the marcs stellar model atmospheres.
While accounting for this line opacity is important at solar metallicity,
the differences between calculations including and excluding line-blocking at
low metallicity are insignificant for the non-local thermodynamic equilibrium
(non-LTE) abundance corrections for
lines.
The line-blocking has no impact on the non-LTE effects of
lines.
The dominant uncertainty in
non-LTE calculations for metal-poor stars
is still the treatment of the inelastic
collisions,
which here have been included using scaling factors to the classical
Drawin formalism,
and whether or not thermalisation of the high
levels to
ground state should be enforced.
Without such thermalisation, the
non-LTE abundance corrections
are substantial in metal-poor stars: about 0.3 dex with efficient (i.e. Drawin-like)
collisions and
0.5 dex without. Without both thermalisation and
collisions, even
lines show significant non-LTE effects
in such stars.
Key words: line: formation / Sun: abundances / stars: abundances / stars: individual: Procyon / stars: individual: HD 140283 / stars: individual: G64-12
© ESO, 2005
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