J/ApJ/873/69ivo://CDS.VizieR/J/ApJ/873/69doi:10.26093/cds/vizier.18730069CDSKochukhov O.Shulyak D.2021-09-07T14:09:44Z2020-09-02T13:34:19ZCDS support team

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

cds-question@unistra.freclipsing-binary-starsradial-velocityvisible-astronomyspectroscopyYY Gem is a short-period eclipsing binary system containing two nearly identical, rapidly rotating, very active early M dwarfs. This binary represents an important benchmark system for calibrating empirical relations between fundamental properties of low-mass stars and for testing theories of interior structure and evolution of these objects. Both components of YY Gem exhibit inflated radii, which has been attributed to poorly understood magnetic activity effects. Despite a long history of magnetic activity studies of this system, no direct magnetic field measurements have been made for it. Here we present a comprehensive characterization of the surface magnetic field in both components of YY Gem. We reconstructed the global field topologies with the help of a tomographic inversion technique applied to high-resolution spectropolarimetric data. This analysis revealed moderately complex global fields with a typical strength of 200-300G and anti-aligned dipolar components. A complementary Zeeman intensification analysis of the disentangled intensity spectra showed that the total mean field strength reaches 3.2-3.4kG in both components of YY Gem. We used these results together with other recent magnetic field measurements of M dwarfs to investigate the relation between the global and small-scale fields in these stars. We also assessed predictions of competing magnetoconvection interior structure models developed for YY Gem, finding that only one of them anticipated the surface field strength compatible with our observations. Results of our starspot mapping of YY Gem do not support the alternative family of theoretical stellar models, which attempts to explain the radius inflation by postulating a large spot filling factor.2019ApJ...873...69Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/873/69CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/cfht : Log of CFHT Exposures (CADC, 1979-)IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)J/MNRAS/390/545 : Magnetic field & velocity of early M dwarfs (Donati+, 2008)J/A+A/478/507 : Distances & atmospheric data of MSU stars (Morales+, 2008)J/MNRAS/390/567 : Magnetic field and velocity of mid M dwarfs (Morin+, 2008)J/ApJ/691/1400 : Absolute properties of CM Dra (Morales+, 2009)J/ApJ/707/671 : IM Vir BVRI photometry & radial velocities (Morales+, 2009)J/MNRAS/407/2269 : Polarisation of a sample of late M dwarfs (Morin+, 2010)J/other/A+ARV/18.67 : Accurate masses and radii of normal stars (Torres+, 2010)J/ApJ/765/126 : Star spot models for M-dwarfs in NGC 2516 (MacDonald+, 2013)J/MNRAS/444/3517 : BCool survey of solar-type stars (Marsden+ 2014)J/MNRAS/441/2361 : Stellar magnetism, age and rotation (Vidotto+, 2014)J/AJ/149/131 : Galactic nearby main-sequence star parameters (Eker+, 2015)J/AJ/152/180 : Bolometric fluxes of EBs in Tycho-2 (Stassun+, 2016)J/A+A/600/A30 : Limb-darkening for TESS satellite (Claret, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/873/69https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/873/69http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/873/69https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/873/69https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/873/69http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/873/69GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/873/69/table1Radial velocity measurements of the YY Gem componentsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[55930.8/55944.1] Reduced Heliocentric Julian Date of mid-exposure; HJD-2400000dtime.epochdoublePhase[0/1] Orbital phasetime.phasefloatSNR[22/318] Signal-to-noise ratio of spectrumstat.snrintHRV-A[-119.05/124.05] Heliocentric radial velocity, component Akm/sspect.dopplerVeloc;pos.heliocentricfloatHRV-B[-118.92/123.22] Heliocentric radial velocity, component Bkm/sspect.dopplerVeloc;pos.heliocentricfloatofit[yn] Used for the orbital fitmeta.codechar