J/ApJS/276/25 O'Connell effect in contact binaries. I. (Kleftogiannis+, 2025)
A search for the O'Connell effect in contact binaries in the era of big sky
surveys. I.
Kleftogiannis G.D., Christopoulou P.-E., Papageorgiou A.
<Astrophys. J. Suppl. Ser., 276, 25 (2025)>
=2025ApJS..276...25K 2025ApJS..276...25K
ADC_Keywords: Binaries, eclipsing; Stars, variable; Surveys; Photometry; Optical
Keywords: Eclipsing binary stars ; Close binary stars ;
W Ursae Majoris variables ; Light curves ; Astronomy data analysis ;
Astronomy databases
Abstract:
Asymmetries between the two maxima of the light curves of contact
binaries, known as the O'Connell effect, have been identified using
the All Sky Automated Survey, All-Sky Automated Survey for Supernovae,
Northern Sky Variability Survey, Optical Gravitational Lensing
Experiment, and Optical Monitoring Camera sky surveys. The morphology
of the mean light curve has been analyzed for a total of 43659 objects
already classified as contact binaries. After applying several filters
and criteria, we present a sample of 797 systems representing the
largest sample to date of maxima asymmetries of EW-type binaries with
|Δm| up to 0.13 mag. We also added information on distance and
temperature from Gaia DR3 and The Large Sky Area Multi-Object Fiber
Spectroscopic Telescope. We investigated the statistical distributions
of periods, temperatures, signs of maximum asymmetry, O'Connell effect
ratio and light-curve asymmetry indices of asymmetry, and their
correlations. While starspots could explain the different maxima
asymmetries in stars with convection zones and differential rotations,
the discovery of sizeable asymmetric maxima in 161 early-type systems
above the upper limit of the Kraft break (T>6700K) may indicate a
different mechanism. We also report systems with peculiar unequal
maxima.
Description:
The surveys used in this investigation are the All Sky Automated
Survey (ASAS)-3, the All-Sky Automated Survey for Supernovae (ASAS-SN),
the Optical Gravitational Lensing Experiment (OGLE) II, OGLE III, the
Northern Sky Variability Survey (NSVS), and the Optical Monitoring
Camera (OMC).
The ASAS observations are carried out in the V and I filters, reaching
a photometric precision of 0.2mag at V=14mag. In this study, we make
use of 5374 eclipsing-binary stars classified as contact
eclipsing-binary stars (EC, EC/ESD, EC/RRC/ESD, EC/DSCT) using Fourier
decomposition, from the ASAS Catalog of Variable Stars (with
observations from 2000 until 2009) in the V band (Pojmanski 2002, II/264).
ASAS-SN is another ground-based optical survey that scans the visible
sky with a cadence of ∼2-3d from V=10-11mag down to V≤17mag,
discovering new EW binaries using V-band and g-band LCs and random
forest classifiers.
We chose those included in the ASAS-SN Catalog of Variable Stars I and
II (Jayasinghe+ 2018MNRAS.477.3145J 2018MNRAS.477.3145J; 2019MNRAS.486.1907J 2019MNRAS.486.1907J -- see II/366)
to be analyzed in this study (V band).
OGLE has monitored the variable sky in V and Ic for almost 30yr, using
the 1.3m Warsaw telescope, located at Las Campanas Observatory, Chile.
The cadence of the OGLE data is typically one observation per night
with about 0.01mag scatter, for a total period of more than 10yr on
the Magellanic Clouds. In this study, we use Ic-band LCs of
321 eclipsing-binary stars classified as contact eclipsing-binary
stars of W UMa type (EW, EB/EW/ELL, EB/EW, etc.) in the OGLE II
database. We used the catalogs of eclipsing-binary stars in the Small
Magellanic Cloud (SMC; Udalski+ 1998, J/AcA/48/563) and
eclipsing-binary stars in the Large Magellanic Cloud (LMC;
Wyrzykowski+ 2003, J/AcA/53/1). In the OGLE III database we use the
Ic-band LCs of 9263 eclipsing-binary stars classified as contact
eclipsing-binary stars (EC) in the LMC (Graczyk+ 2011, J/AcA/61/103;
Pawlak+ 2013, J/AcA/63/323; Pietrukowicz+ 2013, J/AcA/63/115).
The NSVS catalog contains variables between 8 and 15.5mag with
photometric precision of 0.2mag at 15mag using the Robotic Optical
Transient Search Experiment I (ROTSE-I) data collected between
1999 April and 2000 March. Hoffman+ (2009, J/AJ/138/466) classified
4659 variables into several categories after using the Fourier
decomposition approach to analyze the NSVS data. In this study, we use
2332 eclipsing-binary stars classified as contact eclipsing-binary
stars of W UMa type (W).
Finally, we used the Optical Monitoring Camera (OMC) on-board
International Gamma-Ray Astrophysics Laboratory (INTEGRAL)
satellite --provided photometry in the Johnson V band for sources from
V∼7-17mag with accuracy 0.01-0.1mag (for V≤16mag). We used the LCs of
93 eclipsing-binary stars classified as contact eclipsing-binary stars
of W UMa type (EW, EW/DW, EW/KE etc.) in the first INTEGRAL-OMC
catalog of optically variable sources
(Alfonso-Garzon+ 2012, J/A+A/548/A79).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 129 797 Properties of 797 systems with maxima asymmetry (MA)
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See also:
II/287 : Northern Sky Variability Survey (NSVS) (Wozniak+, 2004)
II/264 : ASAS Variable Stars in Southern hemisphere (Pojmanski+, 2002-2005)
II/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
J/AcA/48/563 : BVI phot. of OGLE SMC eclipsing binaries (Udalski+, 1998)
J/AJ/119/1901 : ROTSE all-sky surveys for variable stars (Akerlof+, 2000)
J/AcA/53/1 : OGLE eclipsing binaries in LMC (Wyrzykowski+, 2003)
J/AJ/138/466 : NSVS variables automated classification (Hoffman+, 2009)
J/AcA/61/103 : VI light curves of LMC eclipsing binaries (Graczyk+, 2011)
J/AJ/141/83 : Kepler Mission. I. Eclipsing binaries in DR1 (Prsa+, 2011)
J/A+A/548/A79 : INTEGRAL-OMC opt. variable sources (Alfonso-Garzon+, 2012)
J/AJ/145/80 : LCs of HS Aqr, EG Cep, VW LMi, DU Boo (Djurasevic+, 2013)
J/AcA/63/323 : OGLE-III SMC eclipsing binary stars (Pawlak+, 2013)
J/AcA/63/115 : OGLE-III Gal. disk eclipsing binaries (Pietrukowicz+, 2013)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/AJ/151/68 : Kepler Mission. VII. Eclipsing binaries in DR3 (Kirk+, 2016)
J/AcA/66/421 : Eclipsing binaries in the Magellanic System (Pawlak+, 2016)
J/AcA/66/405 : Gal. bulge eclipsing & ellipsoidal bin. (Soszynski+, 2016)
J/AJ/153/231 : BVR photometry of EPIC 211957146 (Sriram+, 2017)
J/AJ/156/241 : A first cat. of var. stars measured by ATLAS (Heinze+, 2018)
J/ApJS/249/18 : The ZTF catalog of periodic variable stars (Chen+, 2020)
J/ApJS/255/1 : Morphology of OGLE LCs of Eclipsing binaries (Bodi+, 2021)
J/ApJS/254/10 : Compilation of W UMa stars (Latkovic+, 2021)
J/MNRAS/507/104 : Ellipsoidal variables in ASAS-SN catalog (Rowan+, 2021)
J/A+A/663/A115 : Contact binary var. X-ray emission within 1kpc (Liu+, 2022)
J/ApJS/258/16 : TESS Eclipsing Binary stars. I. Sectors 1-26 (Prsa+, 2022)
J/A+A/674/A19 : Ellipsoidal variables with compact companions (Gomel+ 2023)
J/MNRAS/522/29 : 15000 ellipsoidal binary candidates in TESS (Green+, 2023)
J/AJ/165/259 : TESS phot. & radial velocities for 6 K-binaries (Liu+, 2023)
J/A+A/677/A137 : Stellar variability in Gaia DR3 (Maiz Apellaniz+, 2023)
J/AJ/167/280 : Photometry and spectroscopy of V505 Lac (Jeong+, 2024)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 28 A28 --- ID System Name
30- 32 A3 --- Flag Flag (1)
34- 42 F9.5 deg RAdeg Right Ascension (J2000)
44- 52 F9.5 deg DEdeg Declination (J2000)
54- 62 F9.7 d Per [0.2/1.9] Period
64- 67 I4 --- Nobs [77/3100] Number of observations
69- 74 F6.3 mag Delm [-0.13/0.1] Difference in magnitude between
two maxima, Δm
76- 81 F6.3 --- Delm/Afit [-0.09/0.12] Ratio, Delm to amplitude,
|Δm|/Afit
83- 87 A5 --- DeltaI Normalized flux, ΔI
89- 93 F5.3 --- OER [0.499/1.88] O'Connell Effect Ratio indicator
of asymmetry, equation 3
95- 99 F5.3 --- LCA [0.007/0.31] LC Asymmetry indicator of
asymmetry, equation 4
101- 129 A29 --- OName Other name
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Note (1): Flags as follows:
(x) = Cross-match of the sample with Liu+ (2022, J/A+A/663/A115);
found 28 objects detected as X-ray sources by XMM-Newton and ROSAT All
Sky Survey, with T<6200K and |ΔM|∼0.03-0.1mag;
(e) = Cross-match of the sample with Green+ (2023, J/MNRAS/522/29)
catalogue with a search radius of 5 arcsec, resulted in 5 systems with
zero probability to be contact binaries (ASAS J203509-6307.5,
ASASSN-VJ005557.23+442149.5, ASASSN-VJ052545.55-100726.5,
ASASSN-VJ215103.09+351046.3, ASASSN-VJ232539.88+394601.8) and seven
others with low probability.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Oct-2025