Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A vigorous activity cycle mimicking a planetary system in HD200466   Stellar activity can be a source of radial velocity (RV) noise and can
reproduce periodic RV variations similar to those produced by an exoplanet. We
present the vigorous activity cycle in the primary of the visual binary
HD200466, a system made of two almost identical solar-type stars with an
apparent separation of 4.6 arcsec at a distance of 44+/-2 pc. High precision RV
over more than a decade, adaptive optics (AO) images, and abundances have been
obtained for both components. A linear trend in the RV is found for the
secondary. We assumed that it is due to the binary orbit and once coupled with
the astrometric data, it strongly constrains the orbital solution of the binary
at high eccentricities (e~0.85) and quite small periastron of ~21 AU. If this
orbital motion is subtracted from the primary radial velocity curve, a highly
significant (false alarm probability <0.1%) period of about 1300 d is obtained,
suggesting in a first analysis the presence of a giant planet, but it turned
out to be due to the stellar activity cycle. Since our spectra do not include
the Ca~II resonance lines, we measured a chromospheric activity indicator based
on the Halpha line to study the correlation between activity cycles and
long-term activity variations. While the bisector analysis of the line profile
does not show a clear indication of activity, the correlation between the
Halpha line indicator and the RV measurements identify the presence of a strong
activity cycle.

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The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
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The categories of this paper are: adap-org
3
The categories of this paper are: physics