J/A+A/622/A199 Fit parameters & ephemerides of 650 mCP stars (Jagelka+, 2019)
Global properties of the light curves of magnetic, chemically peculiar stars
as a testbed for the existence of dipole-like symmetry in surface structures.
Jagelka M., Mikulasek Z., Huemmerich S., Paunzen E.
<Astron. Astrophys. 622, A199 (2019)>
=2019A&A...622A.199J 2019A&A...622A.199J (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar; Stars, Ap ; Photometry, UBV
Keywords: stars: variables: general - stars: atmospheres -
stars: chemically peculiar
Abstract:
Magnetic, chemically peculiar stars are known for exhibiting surface
abundance inhomogeneities (chemical spots) that lead to photometric
and spectroscopic variability with the rotation period. It is commonly
assumed that the surface structures are causally connected with the
global magnetic field that dominates the photospheric and
subphotospheric layers of these stars. As a rule, the observed
magnetic fields show a simple dipole-like geometry, with the magnetic
axis being noncollinear to the rotational one. The present study aims
at detecting underlying patterns in the distribution of photometric
spots in a sample of 650 magnetic, chemically peculiar stars and
examines their link to the magnetic field topology.
Photometric time-series observations from the ASAS-3 archive were
employed to inspect the light-curve morphology of our sample stars and
divide them into representative classes described using a principal
component analysis. Theoretical light curves were derived from
numerous simulations assuming different spot parameters and following
the symmetry of a simple dipole magnetic field. These were
subsequently compared with the observed light curves.
The results from our simulations are in contradiction with the
observations and predict a much higher percentage of double-wave light
curves than is actually observed. We thereby conclude that the
distribution of the chemical spots does not follow the magnetic field
topology, which indicates that the role of the magnetic field in the
creation and maintenance of the surface structures may be more
subsidiary than what is predicted by theoretical studies.
Description:
Light curves of 650 magnetic chemically peculiar stars were studied
and analyzed. Light curves observed in V filter were fitted by model
with parameters A1, A2 and A3. These parameters are presented here
together with their errors, standard deviation of the fit, values of
rotational period and time of maximum brightness and the single or
double wave character for each star.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 84 650 Fit parameters and ephemerides
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See also:
II/264 : Southern hemisphere ASAS Variable Stars (Pojmanski+, 2002-05)
III/260 : General Catalogue of Ap and Am stars (Renson+ 2009)
J/A+A/581/A138 : Photometric variability in mCP stars (Bernhard+, 2015)
J/AJ/152/104 : New photometrically variable mCP stars (Hummerich+, 2016)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Star Star designation
16- 22 F7.4 mag A1 Value of parameter A1 (1)
24- 30 F7.4 mag A2 Value of parameter A2 (1)
32- 38 F7.4 mag A3 Value of parameter A3 (1)
40- 45 F6.4 mag e_A1 Value of error of parameter A1
47- 52 F6.4 mag e_A2 Value of error of parameter A2
54- 59 F6.4 mag e_A3 Value of error of parameter A2
61- 66 F6.4 mag sigma Standard deviation of the fit
68- 74 F7.3 d P Period (2)
76- 82 F7.2 d M0-2450000 Partial Julian date of time of light curve
maximum (2)
84 I1 --- n [1/2] Wave number (3)
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Note (1): We express the ASAS-3 mCP-star light curves in a simple form with
sufficient accuracy using only three free parameters describing their shape:
F = F0 +F1(Φ)+F2(Φ)+F3(Φ) =
F0 + A1cos(2πΦ) + A2cos(4πΦ) +
A3(2/(sqrt(5))[sin(2πΦ)-0.5sin(4πΦ)],
where Φ=φ-φ0, (φ=frac[(t-Mo)/P]
Note (2): These values are adopted from papers from references
Note (3): Classification indicating if the light curve as follows:
1 = single wave
2 = double wave
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Acknowledgements:
Miroslav Jagelka, jagelka(at)mail.muni.cz
References:
Bernhard et al., 2015A&A...581A.138B 2015A&A...581A.138B, Cat. J/A+A/581/A138
A search for photometric variability in magnetic chemically peculiar stars
using ASAS-3 data
Huemmerich et al., 2016AJ....152..104H 2016AJ....152..104H, Cat. J/AJ/152/104
New Photometrically Variable Magnetic Chemically Peculiar Stars in
the ASAS-3 Archive
(End) Patricia Vannier [CDS] 01-Feb-2019