J/A+A/692/L4ivo://CDS.VizieR/J/A+A/692/L4doi:10.26093/cds/vizier.36929004CDSLi K.Gao X.Guo D.-F.Gao D.-Y.Chen X.Wang L.-H.Xin Y.-X.,Han Y.-X.Kim C.-H.Jeong M.-J.2025-02-24T20:02:17Z2024-12-04T07:30:02ZCDS support team

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

cds-question@unistra.freclipsing-binary-starsephemeridesvisible-astronomyThis paper presents the first analysis of the contact binary TYC 3801-1529-1. We observed four sets of multiple bands complete light curves and one set of radial velocity curve of the primary component. Based on a simultaneous investigation of our observed and TESS light curves and the radial velocity curve, we found that TYC 3801-1529-1 is an extremely low-mass-ratio, medium contact binary with q=0.0356, with the contribution of the third light at a level of about 10%. Its mass ratio is lower than V1187 Her, making TYC 3801-1529-1 the lowest mass-ratio contact binary ever found in the universe. The light curves observed in 2022 are asymmetric, which is aptly explained by a hot spot on the primary component. A 16-year eclipse timings analysis indicates a secular increase orbital period with a rate of dp/dt=7.96(+/-0.35)*10^-7^d/yr. We studied the stability of this target and identified that not only the value of J_spin_/J_orb_, but also the mass ratio surpass the unstable boundary. Hence, TYC 3801-1529-1 presents a challenge to theoretical research and ought to be considered a progenitor of a contact binary merger.2024A&A...692L...4Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/692/L4CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/692/L4https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/692/L4http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/692/L4https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/692/L4https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/692/L4http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/692/L4GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/692/L4/tablea3Eclipse timings of TYC 3801-1529-1recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian date of eclipse (TDB)dtime.epochdoublee_BJDUncertainty in BJDdstat.errordoubleECycle numbermeta.id;meta.maindoubleO-CObserved - Calculateddstat.fit.residualdoubleSourceSourcemeta.bibchar