Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SN 2017fgc: A Fast-Expanding Type Ia Supernova Exploded in Massive Shell
  Galaxy NGC 474   We present extensive optical photometric and spectroscopic observations of
the high-velocity (HV) Type Ia supernova (SN Ia) 2017fgc, covering the phase
from $\sim$ 12 d before to $\sim 389$ d after maximum brightness. SN 2017fgc is
similar to normal SNe Ia, with an absolute peak magnitude of $M_{\rm max}^{B}
\approx$ $-19.32 \pm 0.13$ mag and a post-peak decline of ${\Delta}m_{15}(B)$ =
$1.05 \pm 0.07$ mag. Its peak bolometric luminosity is derived as $1.32 \pm
0.13) \times 10^{43} $erg s$^{-1}$, corresponding to a $^{56}$Ni mass of $0.51
\pm 0.03 M_{\odot}$. The light curves of SN 2017fgc are found to exhibit excess
emission in the $UBV$ bands in the early nebular phase and pronounced secondary
shoulder/maximum features in the $RrIi$ bands. Its spectral evolution is
similar to that of HV SNe Ia, with a maximum-light Si II velocity of $15,000
\pm 150 $km s$^{-1}$ and a post-peak velocity gradient of $\sim$ $120 \pm 10
$km s$^{-1} $d$^{-1}$. The Fe II and Mg II lines blended near 4300 {\AA} and
the Fe II, Si II, and Fe III lines blended near 4800 {\AA} are obviously
stronger than those of normal SNe Ia. Inspecting a large sample reveals that
the strength of the two blends in the spectra, and the secondary peak in the
$i/r$-band light curves, are found to be positively correlated with the
maximum-light Si II velocity. Such correlations indicate that HV SNe~Ia may
experience more complete burning in the ejecta and/or that their progenitors
have higher metallicity. Examining the birthplace environment of SN 2017fgc
suggests that it likely arose from a stellar environment with young and
high-metallicity populations.

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The categories of this paper are: adap-org
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The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-th
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The categories of this paper are: math-ph
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The categories of this paper are: cs
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The categories of this paper are: stat
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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: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: cond-mat
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The categories of this paper are: math
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The categories of this paper are: bayes-an