Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fragmentation Kinematics in Comet 332P/Ikeya-Murakami   We present initial time-resolved observations of the split comet
332P/Ikeya-Murakami taken using the Hubble Space Telescope. Our images reveal a
dust-bathed cluster of fragments receding from their parent nucleus at
projected speeds in the range 0.06 to 3.5 m s$^{-1}$ from which we estimate
ejection times from October to December 2015. The number of fragments with
effective radii $\gtrsim$20 m follows a differential power law with index
$\gamma$ = -3.6$\pm$0.6, while smaller fragments are less abundant than
expected from an extrapolation of this power-law. We argue that, in addition to
losses due to observational selection, torques from anisotropic outgassing are
capable of destroying the small fragments by driving them quickly to rotational
instability. Specifically, the spin-up times of fragments $\lesssim$20 m in
radius are shorter than the time elapsed since ejection from the parent
nucleus. The effective radius of the parent nucleus is $r_e \le$ 275 m
(geometric albedo 0.04 assumed). This is about seven times smaller than
previous estimates and results in a nucleus mass at least 300 times smaller
than previously thought. The mass in solid pieces, $2\times10^9$ kg, is about
4% of the mass of the parent nucleus. As a result of its small size, the parent
nucleus also has a short spin-up time. Brightness variations in time-resolved
nucleus photometry are consistent with rotational instability playing a role in
the release of fragments.

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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: nlin
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: physics