Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non-LTE line formation of Fe in late-type stars - III. 3D non-LTE
  analysis of metal-poor stars   As one of the most important elements in astronomy, iron abundance
determinations need to be as accurate as possible. We investigate the accuracy
of spectroscopic iron abundance analyses using archetypal metal-poor stars. We
perform detailed 3D non-LTE radiative transfer calculations based on 3D
hydrodynamic Stagger model atmospheres, and employ a new model atom that
includes new quantum-mechanical neutral hydrogen collisional rate coefficients.
With the exception of the red giant HD122563, we find that the 3D non-LTE
models achieve Fe i/Fe ii excitation and ionization balance as well as not
having any trends with equivalent width to within modelling uncertainties of
0.05 dex, all without having to invoke any microturbulent broadening; for
HD122563 we predict that the current best parallax-based surface gravity is
over-estimated by 0.5 dex. Using a 3D non-LTE analysis, we infer iron
abundances from the 3D model atmospheres that are roughly 0.1 dex higher than
corresponding abundances from 1D MARCS model atmospheres; these differences go
in the same direction as the non-LTE effects themselves. We make available
grids of departure coefficients, equivalent widths and abundance corrections,
calculated on 1D MARCS model atmospheres and horizontally- and
temporally-averaged 3D Stagger model atmospheres.

22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess