Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Recurring sets of recurring starspot occultations on exoplanet-host
  Qatar-2   We announce the detection of recurring sets of recurring starspot occultation
events in the short-cadence K2 lightcurve of Qatar-2, a K dwarf star transited
every 1.34 d by a hot Jupiter. In total we detect 34 individual starspot
occultation events, caused by five different starspots, occulted in up to five
consecutive transits or after a full stellar rotation. The longest recurring
set of recurring starspot occultations spans over three stellar rotations,
setting a lower limit for the longest starspot lifetime of 58 d. Starspot
analysis provided a robust stellar rotational period measurement of
$18.0\pm0.2$ d and indicates that the system is aligned, having a sky-projected
obliquity of $0\pm8^{\circ}$. A pronounced rotational modulation in the
lightcurve has a period of $18.2\pm1.6$ d, in agreement with the rotational
period derived from the starspot occultations. We tentatively detect an
ellipsoidal modulation in the phase-curve, with a semi-amplitude of 18 ppm, but
cannot exclude the possibility that this is the result of red noise or
imperfect removal of the rotational modulation. We detect no transit-timing and
transit-duration variations with upper limits of 15 s and 1 min, respectively.
We also reject any additional transiting planets with transit depths above 280
ppm in the orbital period region 0.5-30 d.

13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat