Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kepler photometry and optical spectroscopy of the ZZ Lep central star of
  the Planetary Nebula NGC 6826: rotational and wind variability   We present three years of long-cadence and over one year of short-cadence
photometry of the central star of the Planetary Nebula NGC 6826 obtained with
the Kepler spacecraft, and temporally coinciding optical spectroscopy. The
light curves are dominated by incoherent variability on time scales of several
hours, but contain a lower-amplitude periodicity of 1.23799 d. The temporal
amplitude and shape changes of this signal are best explicable with a
rotational modulation, and are not consistent with a binary interpretation. We
argue that we do not observe stellar pulsations within the limitations of our
data, and show that a binary central star with an orbital period less than
seven days could only have escaped our detection in the case of low orbital
inclination. Combining the photometric and spectroscopic evidence, we reason
that the hourly variations are due to a variable stellar wind, and are global
in nature. The physical cause of the wind variability of NGC 6826 and other ZZ
Leporis stars is likely related to the mechanism responsible for wind
variations in massive hot stars.

20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin