Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Central stars of planetary nebulae in the Galactic bulge   Optical high-resolution spectra of five central stars of planetary nebulae
(CSPN) in the Galactic Bulge have been obtained with Keck/HIRES in order to
derive their parameters. Since the distance of the objects is quite well known,
such a method has the advantage that stellar luminosities and masses can in
principle be determined without relying on theoretical relations between both
quantities. By alternatively combining the results of our spectroscopic
investigation with evolutionary tracks, we obtain so-called spectroscopic
distances, which can be compared with the known (average) distance of the
Bulge-CSPN. This offers the possibility to test the validity of model
atmospheres and present date post-AGB evolution. We analyze optical H/He
profiles of five Galactic Bulge CSPN (plus one comparison object) by means of
profile fitting based on state of the art non-LTE modeling tools, to constrain
their basic atmospheric parameters (Teff, log g, helium abundance and wind
strength). Masses and other stellar radius dependent quantities are obtained
from both the known distances and from evolutionary tracks, and the results
from both approaches are compared. The major result of the present
investigation is that the derived spectroscopic distances depend crucially on
the applied reddening law. An "average extinction law" leads to a distance of
10.7 +- 1.2 kpc, which is considerably larger than the Galactic Center distance
of 8 kpc. However, we find a remarkable internal agreement of the individual
spectroscopic distances of our sample objects. Due to the uncertain reddening
correction, the analysis presented here cannot yet be regarded as a consistency
check for our method, and a rigorous test of the CSPN evolution theory becomes
only possible if this problem has been solved.

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The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
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The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn