Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unusual behavior of epicyclic frequencies around rapidly rotating
  compact stars   We report on numerical calculations of orbital and epicyclic frequencies in
nearly circular orbits around rotating neutron stars and strange quark stars.
The FPS equation of state was used to describe the neutron star structure while
the MIT bag model was used to model the equation of state of strange quark
stars. The uniformly rotating stellar configurations were computed in full
general relativity. We find that the vertical epicyclic frequency is very
sensitive to the oblateness of the rotating star. For models of rotating
neutron stars of moderate mass, as well as for strange quark star models, the
sense of the nodal precession of test particle orbits close to the star changes
at a certain stellar rotation rate. These findings may have implications for
models of kHz QPOs.

20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex