J/ApJ/922/122ivo://CDS.VizieR/J/ApJ/922/122doi:10.26093/cds/vizier.19220122CDSLi K.Xia Q.-Q.Kim C.-H.Hu S.-M.Guo D.-F.Jeong M.-J.Chen Xu,Gao D.-Y.2023-07-03T14:22:47Z2023-04-25T09:03:10ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.freclipsing-binary-starsinfrared-photometryvisible-astronomybroad-band-photometryThe cutoff mass ratio is under debate for contact binaries. In this paper, we present the investigation of two contact binaries with mass ratios close to the low mass ratio limit. It is found that the mass ratios of VSX J082700.8+462850 (hereafter J082700) and 1SWASP J132829.37+555246.1 (hereafter J132829) are both less than 0.1 (q~0.055 for J082700 and q~0.089 for J132829). J082700 is a shallow contact binary with a contact degree of ~19%, and J132829 is a deep contact system with a fill-out factor of ~70%. The O-C diagram analysis indicated that the two systems manifested long-term period decreases. In addition, J082700 exhibits a cyclic modulation which is more likely resulting from the Applegate mechanism. In order to explore the properties of extremely low mass ratio contact binaries (ELMRCBs), we carried out a statistical analysis on contact binaries with mass ratios of q~0.1 and discovered that the values of Jspin/Jorb of three systems are greater than 1/3. Two possible explanations can interpret this phenomenon. One explanation is that some physical processes, unknown to date, are not considered when Hut presented the dynamic stability criterion. The other explanation is that the dimensionless gyration radius (k) should be smaller than the value we used (k2=0.06). We also found that the formation of ELMRCBs possibly has two channels. The study of evolutionary states of ELMRCBs reveals that their evolutionary states are similar with those of normal W UMa contact binaries.2021ApJ...922..122Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/922/122CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/287 : Northern Sky Variability Survey (NSVS) (Wozniak+, 2004)I/337 : Gaia DR1 (Gaia Collaboration, 2016)I/345 : Gaia DR2 (Gaia Collaboration, 2018)II/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020)V/119 : Catalogue of field contact binary stars (Pribulla+, 2003)J/ApJ/629/1055 : Evolution of close binary systems (Yakut+, 2005)J/AJ/133/1470 : TAROT suspected variable star catalog (Damerdji+, 2007)J/A+A/465/943 : BVI and RV curves of 5 eclipsing binaries (Szalai+, 2007)J/MNRAS/405/1930 : Period changes of EA-, EB- & EW-types binaries (Liao+, 2010)J/A+A/519/A78 : BVR light curves of KR Com (Zasche+, 2010)J/MNRAS/412/1787 : Physical parameters of 62 eclipsing binaries (Deb+, 2011)J/AJ/146/157 : Differential BVRI phot. of FI Boo (Christopoulou+, 2013)J/AJ/145/100 : Differential BVR light curves of EP And (Lee+, 2013)J/ApJS/208/9 : Colors and temperatures of PMS stars (Pecaut+, 2013)J/ApJS/213/9 : Catalina Surveys periodic variable stars (Drake+, 2014)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/AJ/154/260 : 3 short-period eclipsing binaries BVRI phot. (Pi+, 2017)J/AJ/157/207 : BVR_c_I_c_ light curve observations for VZ Lib (Liao+, 2019)J/ApJ/877/75 : BVRI phot. of DV Psc and known short-period EBs (Pi+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/922/122https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/922/122http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/922/122https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/922/122https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/922/122http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/922/122GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/922/122/fig1Light curves of VSX J082700.8+462850 (J082700) and 1SWASP J132829.37+555246.1 (J132829)StarStarmeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTelTelescope (1)meta.id;instr.telcharFiltFilter (B, V, Rc or Ic)meta.id;instr.filtercharHJDHeliocentric Julian Date of observationdtime.epochdoubledmag[-0.7/1.71] Differential magnitude in Filtmagphot.mag;arith.difffloat