Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Co-spatial UV-optical HST/STIS Spectra of Six Planetary Nebulae: Nebular
  and Stellar Properties   This paper represents the conclusion of a project that had two main goals:
(1) to investigate to what extent planetary nebulae (PNe) are chemically
homogeneous; and (2) to provide physical constraints on the central star
properties of each PN. We accomplished the first goal by using HST/STIS spectra
to measure the abundances of seven elements in numerous spatial regions within
each of six PN (IC 2165, IC 3568, NGC 2440, NGC 5315, NGC 5882, and NGC 7662).
The second goal was achieved by computing a photoionization model of each
nebula, using our observed emission line strengths as constraints. The major
finding of our study is that the nebular abundances of He, C, N, O, Ne, S, and
Ar are consistent with a chemically homogeneous picture for each PN.
Additionally, we found through experimenting with three different density
profiles (constant, Gaussian, and Gaussian with a power-law) that the
determination of the central star's temperature and luminosity is only slightly
sensitive to the profile choice. Lastly, post-AGB evolutionary model
predictions of temperature and luminosity available in the literature were
plotted along with the values inferred from the photoionization model analysis
to yield initial and final mass estimates of each central star.

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The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
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The categories of this paper are: acc-phys
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con