J/A+A/586/A85 HD 18078 uvby light curves (Mathys+, 2016)
HD 18078: a very slowly rotating Ap star with an unusual magnetic field
structure.
Mathys G., Romanyuk I.I., Kudryavtsev D.O., J.D., Landstreet , Pyper D.M.,
Adelman S.J.
<Astron. Astrophys. 586, A85 (2016)>
=2016A&A...586A..85M 2016A&A...586A..85M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar ; Photometry, uvby
Keywords: stars: individual: HD 18078 - stars: chemically peculiar -
stars: rotation - stars: magnetic field
Abstract:
The existence of a significant population of Ap stars with very long
rotation periods (up to several hundred years) has progressively
emerged over the past two decades. However, only lower limits of the
periods are known for most of them because their variations have not
yet been observed over a sufficient timebase.
We determine the rotation period of the slowly rotating Ap star HD
18078 and we derive constraints on the geometrical structure of its
magnetic field.
We combine measurements of the mean magnetic field modulus obtained
from 1990 to 1997 with determinations of the mean longitudinal
magnetic field spanning the 1999-2007 time interval to derive an
unambiguous value of the rotation period. We show that this value is
consistent with photometric variations recorded in the Stromgren uvby
photometric system between 1995 and 2004. We fit the variations of the
two above-mentioned field moments with a simple model to constrain the
magnetic structure.
Description:
This table contains the good observations of HD 18078 obtained with
the Four College Automated Photoelectric Telescope, Washington Camp,
Arizona, United States of America. The data were obtained in the
Stromgren uvby system. It measures the dark count and then, in each
filter, sky-ch-c-v-c-v-c-v-c-ch-sky for each group of variable (v),
check (ch), and comparison (c) stars where sky is a reading of the
sky.
Objects:
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RA (2000) DE Designation(s)
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02 56 32.01 +56 10 41.5 HD 18078 = BD+55 726
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 63 116 FCAPT Stromgren uvby observations of HD 18078
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d HJD Heliocentric Julian Date
13- 18 F6.3 mag u(v-c) u mag difference variable-comparison stars
20- 24 F5.3 mag u(c-ch) u mag difference comparison-check stars
26- 31 F6.3 mag v(v-c) v mag difference variable-comparison stars
33- 37 F5.3 mag v(c-ch) v mag difference comparison-check stars
39- 44 F6.3 mag b(v-c) b mag difference variable-comparison stars
46- 50 F5.3 mag b(c-ch) b mag difference comparison-check stars
52- 57 F6.3 mag y(v-c) y mag difference variable-comparison stars
59- 63 F5.3 mag y(c-ch) y mag difference comparison-check stars
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Acknowledgements:
Diane M. Pyper, dpsmith(at)unlv.nevada.edu
(End) Diane M. Pyper [UNLV], Patricia Vannier [CDS] 26-Nov-2015