Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Early-Phase Spectra of "Hypernova" SN 2002ap   The spectral evolution of the peculiar SN Ic 2002ap during the first 40 days
is presented. The spectra display very broad absorption features, which are
typical of "hypernovae". The maximum expansion velocity measured on the
earliest spectra exceeds 3 times 10^4 km s^{-1}. The spectrum of SN 2002ap at
the epoch of maximum brightness resembles that of SN 1997ef more than that of
SN 1998bw. The spectral evolution of SN 2002ap proceeds at about 1.5 times the
rate of SN 1997ef. The parameterized supernova spectrum synthesis code SYNOW
was used to perform line identification and deduce velocity information from
the early-phase spectra, which are heavily affected by line blending. The
photospheric velocity, as deduced from the fitting results and from the
blueshift of the \ion{Si}{2} lambda 6355 absorption minimum, is lower than in
previously studied hypernovae. At advanced epochs, the \ion{Si}{2} lambda 6355
absorption minimum becomes difficult to distinguish. This may be caused by the
growth of [\ion{O}{1}] lambda lambda 6300, 6364 emission. Together with the
rapid spectral evolution, this suggests that SN 2002ap should enter the nebular
phase sooner than previously studied hypernovae.

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The categories of this paper are: cs
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The categories of this paper are: funct-an
27
The categories of this paper are: comp-gas
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The categories of this paper are: nlin
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: econ
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
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The categories of this paper are: stat
25
The categories of this paper are: patt-sol
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-bio
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The categories of this paper are: eess