Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 17P/Holmes: Contrast in activity between before and after the 2007
  outburst   A Jupiter-family comet, 17P/Holmes, underwent outbursts in 1892 and 2007. In
particular, the 2007 outburst is known as the greatest outburst over the past
century. However, little is known about the activity before the outburst
because it was unpredicted. In addition, the time evolution of the nuclear
physical status has not been systematically studied. Here we study the activity
of 17P/Holmes before and after the 2007 outburst through optical and
mid-infrared observations. We found that the nucleus highly depleted its
near-surface icy component before but became activated after the 2007 outburst.
Assuming a conventional 1-um-sized grain model, we derived a surface fractional
active area of 0.58% +- 0.14% before the outburst whereas it was enlarged by a
factor of ~50 after the 2007 outburst. We also found that large (>=1 mm)
particles could be dominant in the dust tail observed around aphelion. Based on
the size of the particles, the dust production rate was >=170 kg/s at the
heliocentric distance rh = 4.1 AU, suggesting that the nucleus still held
active status around the aphelion passage. The nucleus color was similar to
that of the dust particles and average for a Jupiter-family comet but different
from most Kuiper Belt objects, implying that the color may be inherent to icy
bodies in the solar system. On the basis of these results, we concluded that
more than 76 m surface materials were blown off by the 2007 outburst.

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The categories of this paper are: math
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The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
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The categories of this paper are: q-fin
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The categories of this paper are: nlin
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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: stat