J/AJ/166/83 V838 Cyg; O-C, amplitude & Fourier coeff modulations (Li+, 2023)
Two Different Weak Modulations in ab-type RR Lyrae Variable V838 Cyg, and
Potential Influence of Metal Abundance on Blazhko Modulation.
Li L.-J., Qian S.-B., Shi X.-D., Zhu L.-Y.
<Astron. J., 166, 83 (2023)>
=2023AJ....166...83L 2023AJ....166...83L
ADC_Keywords: Stars, variable; Optical; Photometry
Keywords: RR Lyrae variable stars ; Photometry ; Fundamental parameters
of stars ; Space telescopes
Abstract:
Noting the weakest modulation and relatively high metal abundance of
the Ab-type RR-Lyrae star V838Cyg, we collected the photometric data
of this star from several sky surveys to carry out an in-depth
analysis. The O-C diagram shows that the pulsation period of V838Cyg
increases linearly over a long timescale. In a reanalysis of the
high-precision Kepler data, we confirmed the modulation with a period
of 59.45±0.07days found by Benko et al., and also found an
additional weak modulation with a longer period (840±21 days).
After a series of analyses, we incline to the view that the mechanisms
causing the two modulations are different: the former is more similar
to the typical Blazhko effect, while the mechanism leading to the
latter may be an extrinsic factor. We also collected and compared the
modulation and physical parameters of other Blazhko RRLyrae stars from
several works in the literature, and find that there is a potential
negative correlation between the modulation amplitude (or upper limit
of amplitude) and the metal abundance. We infer that the relatively
high metal abundance will promote convection in the outer stellar
atmosphere, and then inhibit those factors (turbulence, shock wave,
etc.) that may cause Blazhko modulation. Future observations and
research work can be carried out with reference to this viewpoint. We
also introduce the moire effects that appear in the Kepler long-
cadence light curves and their possible interference in the previous
analyses.
Description:
We collect the photometric data of V838Cyg from several sky survey
projects, including the ground data provided by SuperWASP, Super Wide
Angle Search for Planets (SWASP) and ASAS-SN, and the space data from
Kepler and TESS. The former are mainly used to study the long-term
change in pulsation period, while the Kepler data with high accuracy
are used to study the weak modulation of V838Cyg. In addition, the
GEOS RR-Lyr database provides 70 times of light maximum for V838Cyg,
and we use those published ones for O-C analysis.
Objects:
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RA (2000) DE Designation(s) (Period)
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19 14 03.90 +48 11 58.5 V838 Cyg = 2MASS J19140390+4811586 (P=840d)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 31 13494 V838 Cyg TESS light curve
fig2.dat 172 862 O-C, amplitude and Fourier coefficient modulations
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See also:
II/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020)
I/358 : Gaia DR3 Part 4. Variability (Gaia Collaboration, 2022)
J/AJ/108/1016 : Kinematics of local RR lyrae stars. I. (Layden, 1994)
J/A+A/476/307 : Period variations in galactic RRab stars (Le Borgne+, 2007)
J/other/IBVS/5889 : Minima and maxima of 380 variables (Hubscher+, 2009)
J/other/IBVS/5941 : Minima and maxima of 292 variables (Hubscher+, 2010)
J/other/IBVS/5984 : Minima and maxima of 503 variables (Hubscher, 2011)
J/A+A/528/A90 : SuperWASP short period eclipsing binaries (Norton+, 2011)
J/A+A/535/A3 : SuperWASP obs of pulsating Am stars (Smalley+, 2011)
J/AJ/144/39 : Galactic RRab from GEOS RR Lyr Survey (Le Borgne+, 2012)
J/ApJS/213/31 : Blazhko effect from 4yr of Kepler data (Benko+, 2014)
J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/A+A/562/A90 : Times of maximum light of Blazhko RRab stars (Skarka, 2014)
J/ApJ/809/L19 : LCs of RR Lyrae stars V350 Lyr & KIC 7021124 (Henry+, 2015)
J/MNRAS/459/4360 : Field RR Lyrae stars (Liska+, 2016)
J/MNRAS/466/2602 : Blazhko effect in Galactic RR Lyrae (Prudil+, 2017)
J/MNRAS/494/1237 : Blazhko effect in Galactic RR Lyrae II (Skarka+, 2020)
J/AJ/161/193 : BVRI light curve of RR Lyrae V* AX UMa (Li+, 2021)
J/ApJ/912/144 : Metallicity of Gal. RR Lyrae from opt&IR LC (Mullen+, 2021)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 E16.10 d BJD [1683/2769] Barycentric Julian Date; BJD-2457000
18- 31 E14.8 --- DFlux [-7.64/45.5] Change in flux
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Byte-by-byte Description of file: fig2.dat
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Bytes Format Units Label Explanations
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1- 10 F10.5 d Max [132/1591] Time of light maximum; BJD-2454833
12- 19 F8.5 d OCmax1 [-0.02/-0.008] Maximum O-C value (1)
21- 28 F8.5 d OCmax2 [-0.002/0.001] Maximum O-C residuals (2)
30- 36 F7.5 d e_Max [3e-5/0.0005] Uncertainty in Max
38- 47 F10.5 d Min [131/1591] Times of light minimum; BJD-2454833
49- 56 F8.5 d OCmin1 [-0.08/-0.07] Minimum O-C value (1)
58- 65 F8.5 d OCmin2 [-0.002/0.002] Minimum O-C residuals (2)
67- 73 F7.5 d e_Min [0.0001/0.002] Uncertainty in Min
75- 80 F6.4 mag Amp [1.08/1.14] Full amplitude
82- 87 F6.4 mag e_Amp [0.0005/0.009] Uncertainty in Amp
89- 94 F6.4 mag A1 [0.38/0.41] Fourier A1 parameter
96-101 F6.4 mag e_A1 [0.0002/0.004] Uncertainty in A1
103-109 F7.4 mag maxmag [-0.78/-0.72] Magnitude at light maximum
111-116 F6.4 mag e_maxmag [0.0003/0.006] Uncertainty in maxmag
118-123 F6.4 --- R21 [0.46/0.47] Fourier R21 parameter
125-130 F6.4 --- e_R21 [0.0006/0.006] Uncertainty in R21
132-137 F6.4 --- R31 [0.34/0.36] Fourier R31 parameter
139-144 F6.4 --- e_R31 [0.0005/0.005] Uncertainty in R31
146-151 F6.4 --- phi21 [2.29/2.32] Fourier φ21 parameter
153-158 F6.4 --- e_phi21 [0.001/0.04] Uncertainty in phi21
160-165 F6.4 --- phi31 [4.84/4.88] Fourier φ31 parameter
167-172 F6.4 --- e_phi31 [0.002/0.05] Uncertainty in phi31
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Note (1): Calculated by 2454964.58594+0.4802799486*E.
Note (2): The parabola component has been removed.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 12-Mar-2024