Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spectral analysis of the barium central star of the planetary nebula Hen
  2-39   Barium stars are peculiar red giants characterized by an overabundance of
s-process elements along with an enrichment in carbon. These stars are
discovered in binaries with white dwarf companions. The more recently formed of
these stars are still surrounded by a planetary nebula. Precise abundance
determinations of the various s-process elements, especially, of the lightest,
short-lived radionuclide technetium will establish constraints for the
formation of s-process elements in asymptotic giant branch stars as well as
mass transfer through, for example, stellar wind, Roche-lobe overflow, and
common-envelope evolution. We performed a detailed spectral analysis of the
K-type subgiant central star of the planetary nebula Hen 2-39 based on
high-resolution optical spectra obtained with the Ultraviolet and Visual
Echelle Spectrograph at the Very Large Telescope using LTE model atmospheres.
We confirm the effective temperature of $T_\mathrm{eff} = 4350 \pm 150$ K for
the central star of the planetary nebula Hen 2-39. It has a photospheric carbon
enrichment of $[\mathrm{C/H}]= 0.36 \pm 0.08$ and a barium overabundance of
$[\mathrm{Ba/Fe}]= 1.8 \pm 0.5$. We find a deficiency for most of the
iron-group elements (calcium to iron) and establish an upper abundance limit
for technetium ($\log \epsilon_\mathrm{Tc} < 2.5$). The quality of the
available optical spectra is not sufficient to measure abundances of all
s-process elements accurately. Despite large uncertainties on the abundances as
well as on the model yields, the derived abundances are most consistent with a
progenitor mass in the range 1.75-3.00 $M_\odot$ and a metallicity of
$[\mathrm{Fe/H}]= -0.3 \pm 1.0$. This result leads to the conclusion that the
formation of such systems requires a relatively large mass transfer that is
most easily obtained via wind-Roche lobe overflow.

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The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: nlin
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: gr-qc