Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Discovery of Balmer-filaments Encircling SNR RCW 86   We report the discovery of Balmer-dominated filaments along almost the
complete periphery of the supernova remnant RCW 86 (also known as G 315.2-2.3
or MSH 14-63). Using the UM/CTIO Curtis Schmidt telescope, we obtained deep CCD
images in the emission of Halpha and [S II], together with continuum images to
remove stellar confusion. After continuum subtraction, we discovered a network
of Halpha filaments reaching almost completely around the remnant. Most of the
newly identified filaments show no corresponding [S II] emission, indicating
that they belong to the peculiar ''Balmer-dominated'' class of filaments.
Comparison of these Balmer filaments with existing radio and X-ray images of
RCW 86 shows an overall similarity, although interesting differences are
apparent upon detailed inspection. While further observations of these newly
identified optical filaments may eventually provide more detailed information
on the kinematics and distance to RCW 86, the distance currently remains
uncertain. We argue that the shorter distance estimates of ~1 kpc are still
favored.

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The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th
1
The categories of this paper are: cs
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: comp-gas
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: math
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The categories of this paper are: hep-ex
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The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph