Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Making Planet Nine: Pebble Accretion at 250--750 AU in a Gravitationally
  Unstable Ring   We investigate the formation of icy super-Earth mass planets within a
gravitationally unstable ring of solids orbiting at 250-750 AU around a 1 solar
mass star. Coagulation calculations demonstrate that a system of a few large
oligarchs and a swarm of pebbles generates a super-Earth within 100-200 Myr at
250 AU and within 1-2 Gyr at 750 AU. Systems with more than ten oligarchs fail
to yield super-Earths over the age of the solar system. As these systems
evolve, destructive collisions produce detectable debris disks with
luminosities of $10^{-5}$ to $10^{-3}$ relative to the central star.

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The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat