Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Star-planet magnetic interaction and activity in late-type stars with
  close-in planets   Late-type stars interact with their close-in planets through their coronal
magnetic fields. We introduce a theory for the interaction between the stellar
and planetary fields focussing on the processes that release magnetic energy in
the stellar coronae. We consider the energy dissipated by the reconnection
between the stellar and planetary magnetic fields as well as that made
available by the modulation of the magnetic helicity of the coronal field
produced by the orbital motion of the planet. We estimate the powers released
by both processes in the case of axisymmetric and non-axisymmetric, linear and
non-linear force-free coronal fields finding that they scale as v_r (B_s)^(4/3)
(B_p)^(2/3) (R_p)^2, where v_r is the relative velocity between the stellar and
planetary fields, B_s the mean stellar surface field, B_p the planetary field
at the poles, and R_p the radius of the planet. A chromospheric hot spot or a
flaring activity phased to the orbital motion of the planet are found only when
the stellar field is axisymmetric. In the case of a non-axisymmetric field, the
time modulation of the energy release is multiperiodic and can be easily
confused with the intrinsic stellar variability. We apply our theory to the
systems with some reported evidence of star-planet magnetic interaction finding
a dissipated power at least one order of magnitude smaller than that emitted by
the chromospheric hot spots. The phase lags between the planets and the hot
spots are reproduced by our models in all the cases except for upsilon And. In
conclusion, the chromospheric hot spots rotating in phase with the planets
cannot be explained by the energy dissipation produced by the interaction
between stellar and planetary fields as considered by our models and require a
different mechanism.

4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an