Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Critical Examination of Hypernova Remnant Candidates in M101. I. MF83   The SNR candidate MF83 in M101 is coincident with a very luminous X-ray
source. Based on the high X-ray luminosity, it has been suggested that MF83 is
a "hypernova remnant" requiring an explosion energy about two orders of
magnitude higher than normal supernovae. We have analyzed high-quality
ground-based and HST observations of MF83, and find that MF83 is a star
formation region, consisting of a large ionized gas shell and four HII regions
along its periphery. Continuum images show OB associations in these HII regions
and within the large shell. The shell has an expansion velocity of $\sim$50
km/s and a diameter of $\sim$270 pc. The optical properties of this shell in
MF83 are similar to those of X-ray-bright superbubbles in the Large Magellanic
Cloud. If the X-ray emission is indeed diffuse, the implied thermal energy in
MF83 is high, a few $\times10^{52}$ ergs. This amount of thermal energy
requires a large number of concentrated supernova explosions or one powerful
explosion. Future X-ray observations with a high angular resolution are needed
to resolve the diffuse emission and point sources in MF83, in order to
determine more accurately the thermal energy in the shell interior and its
required explosion energy.

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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-th
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: math
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The categories of this paper are: physics
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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: q-bio