Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dynamics of the envelope of a rapidly rotating star or giant planet in
  gravitational contraction   We wish to understand the processes that control the fluid flows of a
gravitationally contracting and rotating star or giant planet. We consider a
spherical shell containing an incompressible fluid that is slowly absorbed by
the core so as to mimick gravitational contraction. We also consider the
effects of a stable stratification that may also modify the dynamics of a
pre-main sequence star of intermediate mass. This simple model reveals the
importance of both the Stewartson layer attached to the core and the boundary
conditions met by the fluid at the surface of the object. In the case of a
pre-main sequence star of intermediate mass where the envelope is stably
stratified, shortly after the birth line, the spin-up flow driven by
contraction overwhelms the baroclinic flow that would take place otherwise.This
model also shows that for a contracting envelope, a self-similar flow of
growing amplitude controls the dynamics. It suggests that initial conditions on
the birth line are most probably forgotten. Finally, the model shows that the
near (Stewartson) layer that lies on the tangent cylinder of the core is likely
a key feature of the dynamics that is missing in 1D models.This layer can
explain the core and envelope rotational coupling that is required to explain
the slow rotation of cores in giant and subgiants stars.

15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th