J/A+A/643/A110 beta Cas BRITE and SMEI light curves (Zwintz+, 2020)
beta Cas: The first delta Scuti star with a dynamo magnetic field.
Zwintz K., Neiner C., Kochukhov O., Ryabchikova T., Pigulski A.,
Muellner M., Steindl T., Kuschnig R., Handler G., Moffat A.F.J.,
Pablo H., Popowicz A., Wade G.A.
<Astron. Astrophys. 643, A110 (2020)>
=2020A&A...643A.110Z 2020A&A...643A.110Z (SIMBAD/NED BibCode)
ADC_Keywords: Combined data ; Photometry, CCD ; Space observations;
Stars, F-type ; Stars, variable ; Stars, bright
Keywords: stars: individual: beta Cas - stars: variables: delta Scuti -
stars: atmospheres - stars: magnetic field - stars: abundances
Abstract:
F type stars are characterised by several physical processes such as
different pulsation mechanisms, rotation, convection, diffusion, and
magnetic fields. The rapidly rotating delta Scuti star beta Cas can be
considered as a benchmark star to study the interaction of several of
these effects.
We investigate the pulsational and magnetic field properties of beta
Cas. We also determine the star's apparent fundamental parameters
and chemical abundances.
Based on photometric time series obtained from three different space
missions (BRITE-Constellation, SMEI, and TESS), we conduct a frequency
analysis and investigate the stability of the pulsation amplitudes
over four years of observations. We investigate the presence of a
magnetic field and its properties using spectropolarimetric
observations taken with the Narval instrument by applying the Least
Square Deconvolution and Zeeman Doppler Imaging techniques.
beta Cas shows only three independent p-mode frequencies down to the
few ppm-level; its highest amplitude frequency is suggested to be
a n=3, l=2, m=0 mode. Its magnetic field structure is quite complex and
almost certainly of a dynamo origin. beta Cas' atmosphere is slightly
deficient in iron peak elements and slightly overabundant in C, O, and
heavier elements.
Atypically for delta Scuti stars, we can only detect three pulsation
modes down to exceptionally low noise levels for beta Cas.The star is
also one of very few delta Scuti pulsators known to date to show a
measurable magnetic field, and the first delta Scuti star with a
dynamo magnetic field. These characteristics make beta Cas an
interesting target for future studies of dynamo processes in the thin
convective envelopes of F-type stars, of the transition region between
fossil and dynamo fields, and the interaction between pulsations and
magnetic field.
Description:
Reduced light curves for beta Cas obtained with the
BRITE-Constellation satellites from 29 August 2015 to 26 October 2015
with BAb and BLb (combined; brite1.dat), from 31 August 2015 to 20
January 2016 with BHr and BTr (combined; brite2.dat), from 7 August
2016 to 30 December 2016 with BAb (brite3.dat), from 13 September 2016
to 1 February 2017 with UBr (brite4.dat), from 7 August 2017 to 3
February 2018 with BAb (brite5.dat), from 8 August 2018 to 4 November
2018 with BAb (brite6.dat), and from 14 September 2018 to 21 January
2019 with BTr (brite7.dat).
The first column lists heliocentric Julian Date for mid-exposure -
2456000.0, the second column is reduced and decorrelated instrumental
BRITE magnitude in millimagnitudes.
Reduced light curve for beta Cas obtained with SMEI from 6 February
2003 to 30 December 2010 (smei.dat) where the first column lists
heliocentric Julian Date - 2450000.0, the second column is the
corrected SMEI magnitude and the third column provides the uncertainty
of column 2.
Objects:
-------------------------------------------
RA (2000) DE Designation(s)
-------------------------------------------
00 09 10.69 +59 08 59.2 beta Cas = HR 21
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
brite1.dat 21 22708 beta Cas reduced light curves with BAb and BLb,
29/08/2015-26/10/2015
brite2.dat 21 25161 beta Cas reduced light curves with BHr and BTr,
31/08/2015-20/01/2016
brite3.dat 21 17728 beta Cas reduced light curves with BAb,
07/08/2016-30/12/2016
brite4.dat 21 23494 beta Cas reduced light curves with UBr,
13/09/2016-01/02/2017
brite5.dat 21 7253 beta Cas reduced light curves with BAb,
08/08/2017-03/02/2018
brite6.dat 21 1316 beta Cas reduced light curves with BAb,
08/08/2018-04/11/2018
brite7.dat 21 41757 beta Cas reduced light curves with BTr,
14/09/2018-21/01/2019
smei.dat 29 28742 beta Cas reduced light curves with SMEI,
06/02/2003-30/12/2010
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See also:
J/A+AS/108/55 : beta Cas V-band light curve (Riboni+, 1994)
Byte-by-byte Description of file: brite?.dat
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Bytes Format Units Label Explanations
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1- 14 F14.9 d Time Heliocentric Julian date (HJD-2456000.0)
15- 21 F7.3 mmag mag Relative reduced instrumental magnitude
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Byte-by-byte Description of file: smei.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.8 d Time Heliocentric Julian date (HJD-2450000.0)
14- 21 F8.5 mag mag Relative reduced instrumental magnitude
22- 29 F8.5 mag e_mag Error of relative reduced instrumental magnitude
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Acknowledgements:
Konstanze Zwintz, Konstanze.Zwintz(at)uibk.ac.at
(End) Patricia Vannier [CDS] 17-Sep-2020