Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Weakly nonlinear theory of the Jeans instability in disk galaxies of
  stars   The reaction of collective oscillations excited in the interaction between
aperiodically growing Jeans-type gravity perturbations and stars of a rapidly
rotating disk of flat galaxies is considered. An equation is derived which
describes the change in the main body of equilibrium distribution of stars in
the framework of the nonresonant weakly nonlinear theory. Certain applications
of the theory to the problem of relaxation of the Milky Way at radii where
two-body relaxation is not effective are explored. The theory, as applied to
the Solar neighborhood, accounts for observed features, such as the shape for
the velocity ellipsoid of stars and the increase in star random velocities with
age.

1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex