J/AJ/168/253ivo://CDS.VizieR/J/AJ/168/253CDSPan Y.Frasca A.Wang J.-X.Fu J.-N.Zhang X.-B.2025-08-01T08:20:05Z2025-07-10T10:45:12ZCDS support team

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

cds-question@unistra.frradial-velocityeclipsing-binary-starsspectroscopyvisible-astronomyk-starsUtilizing data from the Transiting Exoplanet Survey Satellite (TESS) and LAMOST, we present a photometric and spectroscopic investigation of two new K-type low-mass eclipsing binaries, TIC 56913729 and TIC 97729372. Our analysis yields masses and radii for TIC 56913729, M_1_=0.7822+/-0.0054M_{sun}_, R_1_=0.7891+/-0.0021R_{sun}_, and M_2_=0.7532+/-0.0052M_{sun}_, R_2_=0.7648+/-0.0021R_{sun}_. For TIC 97729372, the results are M_1_=0.6410+/-0.0058M_{sun}_, R_1_=0.6537+/-0.0069R_{sun}_ and M_2_=0.6480+/-0.0058M_{sun}_, R_2_=0.6418+/-0.0062R_{sun}_. In addition, by analyzing the out-of-eclipse starspot light variations, the lower limit of starspot coverage varies in different TESS sectors from 2% to 12%. We observed a clear radius inflation in the mass-radius diagram for both stars, when plotted against PARSEC and SPOT isochrones with 1Gyr. Yet, this apparent discrepancy disappears when the comparison is made with either an older PARSEC isochrone (12Gyr) or a SPOT isochrone (250Myr) with high starspot coverage (Fspot ~85%), which is significantly higher than the typical starspot coverage deduced from light curves. Due to the lack of strong age constraints, we cannot firmly exclude that the observed radius inflation may be the result of a post-main-sequence evolutionary effect, although the spectral and kinematic properties of these stars are hardly compatible with 10-12Myr old (Pop II) stars. It is more likely that the radius inflation is produced by the strong magnetic activity in these rapidly rotating stars, even if it is impossible to infer the actual total spot coverage, due to the age uncertainties.2024AJ....168..253Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/168/253CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/287 : Northern Sky Variability Survey (NSVS) (Wozniak+, 2004)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)IV/39 : TESS Input Catalog v8.2 (TIC v8.2) (Paegert+, 2021)V/156 : LAMOST DR7 catalogs (Luo+, 2019)J/MNRAS/328/45 : Late-type stars members of young groups (Montes+, 2001)J/A+A/454/301 : Radial velocities of 6 binaries (Frasca+, 2006)J/ApJ/691/1400 : Absolute properties of CM Dra (Morales+, 2009)J/other/A+ARV/18.67 : Accurate masses and radii of normal stars (Torres+, 2010)J/AJ/153/95 : Catalog of Suspected Nearby Young Stars (Riedel+, 2017)J/ApJ/893/67 : Smoothed amplitudes from Kepler, K2 & TESS phot. (Morris, 2020)J/ApJS/251/15 : LAMOST-Kepler/K2 survey (LK-MRS) first year obs. (Zong+, 2020)J/ApJS/256/14 : RVs from LAMOST MRS DR7 stellar spectra (Zhang+, 2021)J/A+A/664/A78 : Kepler targets class based on LAMOST spectra (Frasca+, 2022)J/ApJS/258/16 : TESS Eclipsing Binary stars. I. Sectors 1-26 (Prsa+, 2022)J/ApJS/258/26 : Spectroscopic binaries from LAMOST MRS. I. (Zhang+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/168/253https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/168/253http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/168/253https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/168/253https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/168/253http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/168/253GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/168/253/table6Radial velocity measurementsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJD[1421/2694] Time, Barycentric Julian Date BJD-2457000dtime.epochdoublePhase[0.05/0.95] Orbital phasetime.phasefloatRVel1[-159/132] Radial velocity of the primary componentkm/sspect.dopplerVelocfloate_RVel1[1.3/21] Uncertainty in RVel1km/sstat.error;spect.dopplerVelocfloatRVel2[-168/131] Radial velocity of the secondary componentkm/sspect.dopplerVelocfloate_RVel2[1.4/27] Uncertainty in RVel2km/sstat.error;spect.dopplerVelocfloatTICTIC identifiermeta.id;meta.mainint