Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Coma Morphology, Numerical Modeling, and Production Rates for Comet
  C/Lulin (2007 N3)   We report on narrowband photometry and extensive imaging observations of
comet C/Lulin (2007 N3) obtained at Lowell Observatory during 2008 and 2009.
Enhanced CN images revealed a double corkscrew morphology with two near-polar
jets oriented approximately east-west, and both CN and dust images showed
nightly rotational variability and seasonal changes in bulk morphology. We
determined a rotational pole direction of RA/Dec = 81/+29 with an obliquity of
97 deg, and a sidereal rotation period of 41.45 +/- 0.05 hr. Monte Carlo
numerical modeling best replicated the observed CN features with an eastern
source area at lat/long -80/125 and a 10 deg radius and a western source area
at lat/long +77/245 and a 20 deg radius, 4 times larger than the eastern
source. An additional small, near-equatorial source was necessary to reproduce
some dust features. Water morphology, based on OH, was quite different than
that of the carbon-bearing species, implying a different driver for the polar
jets such as CO or CO2. Ion tails were detected in decontaminated images from
both the dust and NH filters, likely being H2O+ and OH+, respectively. We
measured water production both before and after perihelion, and extrapolate
peak water production at perihelion to be about 1.0*10^29 molecules/s. We
estimate an active fraction of only 4-5% and a nucleus radius of up to ~8 km.
Our data suggest that Lulin, defined as dynamically new in a statistical sense,
behaves more like a long-period comet due to its nearly asteroidal early
appearance, isolated source regions, and dust properties.

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The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
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The categories of this paper are: bayes-an
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The categories of this paper are: math
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The categories of this paper are: cmp-lg
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The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: ao-sci
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org