J/ApJ/707/671ivo://CDS.VizieR/J/ApJ/707/671doi:10.26093/cds/vizier.17070671CDSMorales J.C.Torres G.Marschall L.A.Brehm W.2026-05-19T14:24:40Z2012-01-31T14:54:10ZCDS support team

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

cds-question@unistra.freclipsing-binary-starsradial-velocityinfrared-photometryvisible-astronomybroad-band-photometryWe report extensive spectroscopic and differential photometric BVRI observations of the active, detached, 1.309-day double-lined eclipsing binary IM Vir, composed of a G7-type primary and a K7 secondary. With these observations, we derive accurate absolute masses and radii of M1=0.981+/-0.012M_{sun}_, M2=0.6644+/-0.0048M_{sun}_, R1=1.061+/-0.016R_{sun}_, and R2=0.681+/-0.013R_{sun}_ for the primary and secondary, with relative errors under 2%. The effective temperatures are 5570+/-100K and 4250+/-130K, respectively. The significant difference in mass makes this a favorable case for comparison with stellar evolution theory. We find that both stars are larger than the models predict, by 3.7% for the primary and 7.5% for the secondary, as well as cooler than expected, by 100K and 150K, respectively. These discrepancies are in line with previously reported differences in low-mass stars, and are believed to be caused by chromospheric activity, which is not accounted for in current models. The effect is not confined to low-mass stars: the rapidly rotating primary of IM Vir joins the growing list of objects of near-solar mass (but still with convective envelopes) that show similar anomalies. The comparison with the models suggests an age of 2.4Gyr for the system, and a metallicity of [Fe/H]~-0.3 that is consistent with other indications, but requires confirmation.2009ApJ...707..671Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/707/671CatalogResearchIsServedByTAP VizieR generic servicerelated-toV/128 : Chromospherically Active Binaries. Third version (Eker+, 2008)V/136 : Teff and metallicities for Tycho-2 stars (Ammons+, 2006)J/MNRAS/416/2477 : STEREO observations of variable stars (Wraight+, 2011)J/PASP/120/1128 : Calibrated griz magnitudes of Tycho star (Ofek, 2008)J/A+A/446/785 : Catalogue of eclipsing variables (Malkov+, 2006)J/MNRAS/349/1069 : Chromospherically active binaries (Karatas+, 2004)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/707/671https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/707/671http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/707/671https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/707/671https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/707/671http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/707/671GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/707/671/table1Radial velocity measurements of IM VirPhaseOrbital phasetime.phasefloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDHeliocentric Julian Datedtime.epochdoubleRV1Primary radial velocitykm/sspect.dopplerVelocfloatRV2Secondary radial velocitykm/sspect.dopplerVelocfloate_RV1The 1{sigma} error in RV1km/sstat.errorfloate_RV2The 1{sigma} error in RV2km/sstat.errorfloat(O-C)1Primary (O-C) valuekm/sstat.fit.residualfloat(O-C)2Secondary (O-C) valuekm/sstat.fit.residualfloatJ/ApJ/707/671/BVRICombined table from original tablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDHeliocentric Julian Datedtime.epochdoublePhaseOrbital phasetime.phasefloatC-VComparison star minus IM Vir differential magnitudemagphot.mag;arith.difffloatC-ChComparison minus check star differential magnitudemagphot.mag;arith.difffloatFFilterinstr.bandpasschar