J/ApJ/950/92ivo://CDS.VizieR/J/ApJ/950/92CDSTang S.-Y.Stahl A.G.Prato L.Schaefer G.H.Johns-Krull C.M.,Skiff B.A.Beichman C.A.Uyama T.2025-10-01T06:29:29Z2025-09-03T10:28:13ZCDS support team

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

cds-question@unistra.frmultiple-starsvisible-astronomyspectroscopyinfrared-astronomyradial-velocityphotometryThe stellar companion to the weak-line T Tauri star DI Tau A was first discovered by the lunar occultation technique in 1989 and was subsequently confirmed by a speckle imaging observation in 1991. It has not been detected since, despite being targeted by five different studies that used a variety of methods and spanned more than 20yr. Here, we report the serendipitous rediscovery of DI Tau B during our Young Exoplanets Spectroscopic Survey (YESS). Using radial velocity data from YESS spanning 17yr, new adaptive optics observations from Keck II, and a variety of other data from the literature, we derive a preliminary orbital solution for the system that effectively explains the detection and (almost all of the) non-detection history of DI Tau B. We estimate the dynamical masses of both components, finding that the large mass difference (q~0.17) and long orbital period (>~35yr) make the DI Tau system a noteworthy and valuable addition to studies of stellar evolution and pre-main-sequence models. With a long orbital period and a small flux ratio (f2/f1) between DI Tau A and B, additional measurements are needed for a better comparison between these observational results and pre-main-sequence models. Finally, we report an average surface magnetic field strength (\bar{B}) for DI Tau A, of ~0.55kG, which is unusually low in the context of young active stars.2023ApJ...950...92Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/950/92CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)II/332 : c2d Spitzer final data release (DR4) (Evans+, 2003)II/328 : AllWISE Data Release (Cutri+ 2013)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)J/ApJS/101/117 : UBVRIJHKLMNQ photometry in Taurus-Auriga (Kenyon+ 1995)J/A+A/461/183 : Variability of classical T Tauri (Grankin+, 2007)J/A+A/479/827 : UBVR LCs of weak-line T Tauri stars (Grankin+, 2008)J/PASJ/60/209 : Faint companions around YSOs in TMC (Itoh+, 2008)J/ApJ/731/8 : Multiple star formation in Taurus-Auriga (Kraus+, 2011)J/ApJ/745/119 : Companions to young stars. I. ChaI & Tau (Nguyen+, 2012)J/ApJ/786/97 : Photospheric properties of T Tauri stars (Herczeg+, 2014)J/MNRAS/441/2361 : Stellar magnetism, age and rotation (Vidotto+, 2014)J/ApJ/799/155 : Sub-stellar companions in Taurus (Daemgen+, 2015)J/A+A/587/A65 : Visible and near-infrared solar spectra (Reiners+, 2016)J/A+A/638/A85 : 3Dview of Taurus with Gaia & Herschel (Roccatagliata+, 2020)J/AJ/160/35 : NIR phot. in the T Tauri system with Keck (Schaefer+, 2020)J/ApJ/921/53 : IGRINS YSO survey. I. Tau-Aur (Lopez-Valdivia+, 2021)J/A+A/649/A3 : Gaia EDR3 photometric passbands (Riello+, 2021)J/AJ/161/283 : Radial velocities of 4 stars with IGRINS (Stahl+, 2021)J/ApJ/925/21 : IRTF/iSHELL K-band sp. obs. of PMS stars (Flores+, 2022)J/AJ/163/156 : THYME. VI. TOI-1227 radial velocity (Mann+, 2022)J/ApJ/928/134 : NIR phot. & opt. veiling in T Tauri stars (Sullivan+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/950/92https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/950/92http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/950/92https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/950/92https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/950/92http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/950/92GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/950/92/table3DI Tau radial velocitiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs[2005/2022] Year of the observation'Y:M:D'time.epochJD[3374.6/9901.8] Julian Date; JD-2450000dtime.epochdoubleRVel[13.2/16.9] Radial velocitykm/sspect.dopplerVelocfloate_RVel[0.05/0.6] Uncertainty in RVelkm/sstat.error;spect.dopplerVelocfloatTypeObservation type (1)meta.code;instr;em.wlcharJ/ApJ/950/92/table4DI Tau Lowell Observatory V photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[2456256.6/2459610.7] Heliocentric Julian Datedtime.epochdoubleVmag[12.83/12.96] Apparent V band magnitudemagphot.mag;em.opt.Vfloate_Vmag[0.001/0.05] Uncertainty in Vmagmagstat.error;phot.mag;em.opt.Vfloat