Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lonely planets and light belts: the Statistical Mechanics of
  Gravitational Systems   In this paper we propose a notion of stability, that we call $\epsilon
-N$-stability, for systems of particles interacting via Newton's gravitational
potential, and orbiting a much bigger object. For these systems the usual
thermodynamical stability condition, ensuring the possibility to perform the
thermodynamical limit, fails, but one can use as relevant parameter the maximum
number of particles $N$ that guarantees the $\epsilon -N$-stability. With some
judicious but not particularly optimized estimates, borrowed from the classical
theory of equilibrium statistical mechanics, we show that our model has a good
fit with the data observed in the Solar System, and it gives a reasonable
interpretation of some of its global properties.

20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn