Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Water ice in the Kuiper belt   We examine a large collection of low resolution near-infrared spectra of
Kuiper belt objects and centaurs in an attempt to understand the presence of
water ice in the Kuiper belt. We find that water ice on the surface of these
objects occurs in three separate manners: (1) Haumea family members uniquely
show surfaces of nearly pure water ice, presumably a consequence of the
fragmentation of the icy mantle of a larger differentiated proto-Haumea; (2)
large objects with absolute magnitudes of $H<3$ (and a limited number to H=4.5)
have surface coverings of water ice - perhaps mixed with ammonia - that appears
to be related to possibly ancient cryovolcanism on these large objects; and (3)
smaller KBOs and centaurs which are neither Haumea family members nor
cold-classical KBOs appear to divide into two families (which we refer to as
"neutral" and "red"), each of which is a mixture of a common nearly-neutral
component and either a slightly red or very red component that also includes
water ice. A model suggesting that the difference between neutral and red
objects is due to formation in an early compact solar system either inside or
outside, respectively, of the ~20 AU methanol evaporation line is supported by
the observation that methanol is only detected on the reddest objects, which
are those which would be expected to have the most of the methanol containing
mixture.

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The categories of this paper are: cond-mat
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The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: stat
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The categories of this paper are: funct-an
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
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The categories of this paper are: math
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The categories of this paper are: mtrl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: q-bio