Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical and Infrared Spectroscopy of SN 1999ee and SN 1999ex   We report optical and infrared spectroscopic observations of the Type Ia SN
1999ee and the Type Ib/c SN 1999ex, both of which were hosted by the galaxy IC
5179. For SN 1999ee we obtained a continuous sequence with an unprecedented
wavelength and temporal coverage beginning 9 days before maximum light and
extending through day 42. Before maximum light SN 1999ee displayed a normal
spectrum with a strong Si II 6355 absorption, thus showing that not all
slow-declining SNe are spectroscopically peculiar at these evolutionary phases.
A comparative study of the infrared spectra of SN 1999ee and other Type Ia
supernovae shows that there is a remarkable homogeneity among the Branch-normal
SNe Ia during their first 60 days of evolution. SN 1991bg-like objects, on the
other hand, display spectroscopic peculiarities at infrared wavelengths. SN
1999ex was characterized by the lack of hydrogen lines, weak optical He I
lines, and strong He I 10830,20581, thus providing an example of an
intermediate case between pure Ib and Ic supernovae. We conclude therefore that
SN 1999ex provides first clear evidence for a link between the Ib and Ic
classes and that there is a continuous spectroscopic sequence ranging from the
He deficient SNe Ic to the SNe Ib which are characterized by strong optical He
I lines.

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The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: hep-ex
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The categories of this paper are: q-bio
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: stat
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The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: cs
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The categories of this paper are: physics
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The categories of this paper are: hep-th