Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Survey of Multiple Planet Systems   As of August 2008, over 30 multiple exoplanet systems are known, and 28% of
stars with planets show significant evidence of a second companion. I briefly
review these 30 systems individually, broadly grouping them into five
categories: 1) systems with 3 or more giant (Msini > 0.2 M_Jup) planets, 2)
systems with two giant planets in mean motion resonance (MMR), 3) systems with
two giant planets not in MMR but whose dynamical evolution is affected by
planet-planet interactions, 4) highly hierarchical systems, having two giant
planets with very large period ratios (> 30:1), and 5) systems of
``Super-Earths'', containing only planets with (Msini < 20 M_Earth).
  It now appears that eccentricities are not markedly higher among planets in
known multiple planet systems, and that planets with Msini < 1 M_Jup have lower
eccentricities than more massive planets. The distribution of semimajor axes
for planets in multiplanet systems does not show the 3-day pile-up or the 1 AU
"jump" of the apparently-single planet distribution.

16
The categories of this paper are: stat
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
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The categories of this paper are: hep-th