Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the migration of three planets in a protoplanetary disc and the
  formation of chains of mean motion resonances   We study the migration of three-planet systems in an irradiated 1+1D
$\alpha$-disc with photoevaporation. We performed $2700$ simulations with
various planets' masses and initial orbits. We found that most of the systems
which ended up as compact configurations form chains of mean motion resonances
(MMRs) of the first and higher orders. Most of the systems involved in chains
of MMRs are periodic configurations. The period ratios of such system, though,
are not necessarily close to exact commensurability. If a given system resides
in a divergent migration zone in the disc, the period ratios increase and
evolve along resonant divergent migration paths at ($P_2/P_1,
P_3/P_2)$-diagram, where $P_1, P_2, P_3$ are the orbital periods of the first,
second and third planet, respectively. The observed systems, though, do not lie
on those paths. We show that an agreement between the synthetic and the
observed systems distributions could be achieved if the orbital circularization
was slower than it results from models of the planet-disc interactions.
Therefore, we conclude that most of those systems unlikely formed as a result
of divergent migration out of nominal chains of MMRs.

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The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol