Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exploring circumstellar effects on the lithium and calcium abundances in
  massive Galactic O-rich AGB stars   We previously explored the circumstellar effects on the Rb and Zr abundances
in massive Galactic O-rich AGB stars. Here we are interested in the role of the
extended atmosphere in the case of Li and Ca. Li is an important indicator of
HBB while the total Ca in these stars could be affected by neutron captures.
The Li abundances were previously studied with hydrostatic models, while the Ca
abundances have been determined for the first time. We use a modified version
of Turbospectrum and consider the presence of a gaseous circumstellar envelope
and radial wind. The new Li abundances derived with the pseudo-dynamical models
are very similar to those obtained from hydrostatic models (the average
difference is 0.18 dex), with no difference for Ca. The Li and Ca content in
these stars is only slightly affected by the presence of a circumstellar
envelope. We also found that the Li I and Ca I line profiles are not very
sensitive to variations of the model wind parameters. The new Li abundances
confirm the Li-rich nature of the sample stars, supporting the activation of
HBB in massive Galactic AGB stars. This is in good agreement with the
theoretical predictions for solar metallicity AGB models from ATON, Monash, and
NuGrid/MESA but is at odds with the FRUITY database, which predicts no HBB
leading to the production of Li. Most sample stars display nearly solar Ca
abundances that are consistent with the available s-process nucleosynthesis
models for solar metallicity massive AGB stars, which predict overproduction of
46Ca relatively to the other Ca isotope and the creation of the radiactive
isotope 41Ca but no change in the total Ca abundance. A minority of the stars
seem to show a significant Ca depletion (by up to 1.0 dex). Possible
explanations are offered to explain their apparent and unexpected Ca depletion.

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The categories of this paper are: q-bio
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: q-alg
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: cond-mat