Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Possible Detection of X-Ray Emitting Circumstellar Material in the
  Synchrotron-Dominated Supernova Remnant RX J 1713.7-3946   We report on a discovery of an X-ray emitting circumstellar material knot
inside the synchrotron dominant supernova remnant (SNR) RX J1713.7-3946. This
knot was previously thought to be a Wolf-Rayet star (WR 85), but we realized
that it is in fact $\sim$40$^{\prime\prime}$ away from WR 85, indicating no
relation to WR 85. We performed high-resolution X-ray spectroscopy with the
Reflection Grating Spectrometer (RGS) on board XMM-Newton. The RGS spectrum
clearly resolves a number of emission lines, such as N Ly$\alpha$, O
Ly$\alpha$, Fe XVIII, Ne X, Mg XI, and Si XIII. The spectrum can be well
represented by an absorbed thermal emission model with a temperature of $k_{\rm
B}T_{\rm e} = 0.65\pm 0.02$ keV. The elemental abundances are obtained to be
${\rm N/H} = 3.5\pm 0.8{\rm \left(N/H\right)_{\odot}}$, ${\rm O/H} =
0.5\pm0.1{\rm \left(O/H\right)_{\odot}}$, ${\rm Ne/H} = 0.9\pm0.1{\rm
\left(Ne/H\right)_{\odot}}$, ${\rm Mg/H} = 1.0\pm0.1{\rm
\left(Mg/H\right)_{\odot}}$, ${\rm Si/H} = 1.0\pm0.2{\rm
\left(Si/H\right)_{\odot}}$, and ${\rm Fe/H} = 1.3\pm0.1{\rm
\left(Fe/H\right)_{\odot}}$. The enhanced N abundance with others being about
the solar values allows us to infer that this knot is circumstellar material
ejected when the progenitor star evolved into a red supergiant. The abundance
ratio of N to O is obtained to be $\rm N/O =
6.8_{-2.1}^{+2.5}\left(N/O\right)_{\odot}$. By comparing this to those in outer
layers of red supergiant stars expected from stellar evolution simulations, we
estimate the initial mass of the progenitor star to be $15\, \rm M_{\odot}
\lesssim \rm M \lesssim 20\, \rm M_{\odot}$.

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The categories of this paper are: cs
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The categories of this paper are: nlin
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The categories of this paper are: math-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: q-alg
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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ex
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The categories of this paper are: q-fin
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The categories of this paper are: eess
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The categories of this paper are: dg-ga