Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: C/2010 U3 (Boattini): A Bizarre Comet Active at Record Heliocentric
  Distance   We present a photometric and dynamical study of comet C/2010 U3 (Boattini),
which was seen active in prediscovery data as early as 2005 November at a new
inbound record heliocentric distance $r_{\rm H} = 25.8$ au. Two outburst events
around 2009 and 2017 were observed. The coma and tail of the comet consist of
dust grains of $\sim$10 $\mu$m in radius, ejected protractedly at speeds
$\lesssim$50 m s$^{-1}$ near the subsolar point, and are subjected to the
Lorentz force, solar gravitation and radiation pressure force altogether. The
prolonged activity indicates that sublimation of supervolatiles (e.g., CO,
CO$_2$) is at play, causing a net mass-loss rate $\gtrsim$1 kg s$^{-1}$. To
sustain the mass loss, the nucleus radius has to be $\gtrsim$0.1 km. The color
of the cometary dust, similar to other long-period comets, is redder than the
solar colors, but we also observed potential color variations when the comet
was at $10 < r_{\rm H} < 15$ au, concurrent with the onset of crystallisation
of amorphous water ice, if at all. Using publicly available and our refined
astrometric measurements, we estimated the precise trajectory of the comet and
propagated it backward to its previous perihelion. We found that the comet has
visited the planetary region $1.96 \pm 0.04$ Myr ago, with barycentric
perihelion distance $q = 8.364 \pm 0.004$ au. Thus, C/2010 U3 (Boattini) is
almost certainly a dynamically old comet from the Oort cloud, and the observed
activity cannot be caused by retained heat from the previous apparition.

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The categories of this paper are: nucl-th
2
The categories of this paper are: math
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ph
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The categories of this paper are: stat
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg