Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: HATS-15 b and HATS-16 b: Two massive planets transiting old G dwarf
  stars   We report the discovery of HATS-15 b and HATS-16 b, two massive transiting
extrasolar planets orbiting evolved ($\sim 10$ Gyr) main-sequence stars. The
planet HATS-15 b, which is hosted by a G9V star ($V=14.8$ mag), is a hot
Jupiter with mass of $2.17\pm0.15\, M_{\mathrm{J}}$ and radius of
$1.105\pm0.0.040\, R_{\mathrm{J}}$, and completes its orbit in nearly 1.7 days.
HATS-16 b is a very massive hot Jupiter with mass of $3.27\pm0.19\,
M_{\mathrm{J}}$ and radius of $1.30\pm0.15\, R_{\mathrm{J}}$; it orbits around
its G3 V parent star ($V=13.8$ mag) in $\sim2.7$ days. HATS-16 is slightly
active and shows a periodic photometric modulation, implying a rotational
period of 12 days which is unexpectedly short given its isochronal age. This
fast rotation might be the result of the tidal interaction between the star and
its planet.

20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
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The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
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The categories of this paper are: econ
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol
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The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga