J/AJ/164/34ivo://CDS.VizieR/J/AJ/164/34doi:10.26093/cds/vizier/be-54-12CDSMorales L.M.Sandquist E.L.Schaefer G.H.Farrington C.D.Klement R.,Bedin L.R.Libralato M.Malavolta L.Nardiello D.Orosz J.A.,Monnier J.D.Kraus S.Le Bouquin J.-B.Anugu N.ten Brummelaar T.,Davies C.L.Ennis J.Gardner T.Lanthermann C.2026-07-02T11:44:14Z2025-09-29T15:16:50ZCDS support team

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

cds-question@unistra.frmultiple-starsvisible-astronomyspectroscopyopen-star-clustersWe observe the brightest member of the Praesepe cluster, {epsilon} Cnc, to precisely measure the characteristics of the stars in this binary system, en route to a new measurement of the cluster's age. We present spectroscopic radial velocity measurements and interferometric observations of the sky-projected orbit to derive the masses, which we find to be M1/M_{sun}_=2.420+/-0.008 and M2/M_{sun}_=2.226+/-0.004. We place limits on the color-magnitude positions of the stars by using spectroscopic and interferometric luminosity ratios while trying to reproduce the spectral energy distribution of {epsilon} Cnc. We reexamine the cluster membership of stars at the bright end of the color-magnitude diagram using Gaia data and literature radial velocity information. The binary star data are consistent with an age of 637+/-19Myr, as determined from MIST model isochrones. The masses and luminosities of the stars appear to select models with the most commonly used amount of convective core overshooting.2022AJ....164...34Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/164/34CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/gcvs : General Catalogue of Variable Stars (Samus+, 2007-2017)B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2020)II/84 : 13-color photometry of 1380 bright stars (Johnson+ 1975)II/7 : UBVRIJKLMNH Photoelectric Catalogue (Morel+ 1978)II/97 : ANS UV Catalogue of Point Sources (Wesselius+ 1982)II/297 : AKARI/IRC mid-IR all-sky Survey (ISAS/JAXA, 2010)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)VII/233 : 2MASS All-Sky Extended Source Cat. (XSC) (IPAC/UMass, 2003-2006)J/AJ/106/637 : ICCD speckle observations. IX (Mason+, 1993)J/AJ/108/2299 : ICCD speckle observations of binary stars. XI. (Hartkopf+ 1994)J/AJ/114/699 : Spectrophotometry in open clusters (Clampitt+ 1997)J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)J/A+AS/129/9 : Delta Sct stars in Praesepe (Pena+ 1998)J/A+A/333/897 : Mass segregation in open clusters (Raboud+ 1998)J/ApJ/521/682 : Binaries in the Praesepe and Coma clusters (Abt+, 1999)J/A+AS/137/451 : Radial velocities. IX. (Grenier+, 1999)J/A+A/354/881 : RVs of Praesepe & Hyades Am stars (Debernardi+ 2000)J/AJ/119/3084 : ICCD speckle obs. of binary stars. XXIII. (Hartkopf+, 2000)J/A+A/393/897 : Rotational velocities of A-type stars II. (Royer+, 2002)J/ApJ/697/1578 : A debris disk study of Praesepe (Gaspar+, 2009)J/A+A/525/A2 : Eclipsing binaries in NGC6791 (Brogaard+, 2011)J/A+A/535/A30 : Chem abundance of 12 stars in open clusters (Carrera+, 2011)J/MNRAS/413/2218 : Stellar rotation in Hyades and Praesepe (Delorme+, 2011)J/A+A/543/A106 : UBVRI photometry in NGC6791 (Brogaard+, 2012)J/A+A/546/A61 : Radial velocities for XHIP catalogue (de Bruijne+, 2012)J/MNRAS/442/2081 : Praesepe members light curves (Kovacs+, 2014)J/A+A/580/A23 : Stroemgren-Crawford uvby{beta} phot. cat. (Paunzen, 2015)J/AJ/152/213 : Interferometry & spec. of sigma Orionis (Schaefer+, 2016)J/AJ/153/128 : WOCS. LXXV. Hyades&Praesepe stellar Li data (Cummings+, 2017)J/ApJ/842/83 : Praesepe members rot. periods from K2 LCs (Douglas+, 2017)J/AJ/153/212 : Obs. of binary stars at the WIYN telescope (Horch+, 2017)J/AJ/154/110 : Orbits from SOAR speckle interferometry. II. (Tokovinin, 2017)J/A+A/618/A93 : Gaia DR2 open clusters in the Milky Way (Cantat-Gaudin+, 2018)J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)J/ApJ/879/100 : K2 rot. periods for Hyades & Praesepe members (Douglas+, 2019)J/A+A/627/A4 : Praesepe (NGC 2632) and its tidal tails (Roeser+, 2019)J/A+A/621/L2 : Hyades tidal tails revealed by Gaia DR2 (Roeser+, 2019)J/A+A/633/A38 : EW of 10 solar-type stars of Praesepe (D'Orazi+, 2020)J/ApJ/919/100 : Abundances of 6 stars in Praesepe cluster (Vejar+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/164/34https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/164/34http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/164/34https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/164/34https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/164/34http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/164/34GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/164/34/table8Radial velocity measurements and their associated spectra for epsilon Cnc A and BrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[22384/58969] Modified Julian Date (1)dtime.epochdoubleRVelA[-27.9/86.1] Radial velocity of {epsilon} Cnc Akm/sspect.dopplerVelocfloate_RVelA[0.1/3] RVelA uncertaintykm/sstat.error;spect.dopplerVelocfloatRVelB[-20.5/95.6] Radial velocity of {epsilon} Cnc Bkm/sspect.dopplerVelocfloate_RVelB[1.3/4.1] RVelB uncertaintykm/sstat.error;spect.dopplerVelocfloatPhase[0.06/0.94] Orbital phasetime.phasefloatTelTelescope used for the observation (2)instrcharSpAssociated spectrum at MJD with link to interactive plot (column added by CDS)meta.codecharFileLink to the spectrum file in MRT format (column added by CDS)meta.ref;pos.framechar