Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical and NIR observations of the nearby type Ia supernova SN 2014J   Optical and NIR observations of the type Ia supernova SN 2014J in M82 are
presented. The observed light curves are found to be similar to normal SNe Ia,
with a decline rate parameter $\Delta m_{15}(B) = 1.08 \pm 0.03$. The supernova
reached $B$-band maximum on JD 2456690.14, at an apparent magnitude $m_B(max) =
11.94$. The optical spectra show a red continuum with deep interstellar Na~{\sc
i} absorption, but otherwise resemble those of normal SNe Ia. The Si~{\sc ii}
$\lambda 6355$ feature indicates a velocity of $\sim 12\,000$ km s$^{-1}$ at
$B$-band maximum, which places SN 2014J at the border of the Normal Velocity
and High Velocity group of SNe Ia. The velocity evolution of SN 2014J places it
in the Low Velocity Gradient subclass, whereas the equivalent widths of Si~{\sc
ii} features near $B$-band maximum place it at the border of the Core Normal
and Broad Line subclasses of SNe Ia. An analytic model fit to the bolometric
light curve indicates that a total of $\sim 1.3$ M$_{\odot}$ was ejected in the
explosion, and the ejected $^{56}$Ni mass $M_{Ni} \sim 0.6$ M$_{\odot}$. The
low [Fe~{\sc iii}] $\lambda4701$ to [Fe~{\sc ii}] $\lambda5200$ ratio in the
nebular spectra of SN 2014J hints towards clumpiness in the ejecta. Optical
broadband, linear polarimetric observations of SN 2014J obtained on four epochs
indicate an almost constant polarization ($P_{\rm R} \sim$2.7 per cent;
$\theta$ $\sim$37$^\circ$), which suggests that the polarization signal is of
interstellar origin.

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The categories of this paper are: hep-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: stat
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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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: chem-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an