J/ApJ/891/171ivo://CDS.VizieR/J/ApJ/891/171doi:10.26093/cds/vizier.18910171CDSZhang Z.Liu M.C.Hermes J.J.Magnier E.A.Marley M.S.Tremblay P.-E.,Tucker M.A.Do A.Payne A.V.Shappee B.J.2022-01-17T13:06:37Z2021-09-10T09:52:34ZCDS support team

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

cds-question@unistra.frvisible-astronomyspectroscopyinfrared-astronomywhite-dwarf-starst-dwarfsmultiple-starsWe present the first discovery from the COol Companions ON Ultrawide orbiTS (COCONUTS) program, a large-scale survey for wide-orbit planetary and substellar companions. We have discovered a comoving system COCONUTS-1, composed of a hydrogen-dominated white dwarf (PSOJ058.9855+45.4184; d=31.5pc) and a T4 companion (PSOJ058.9869+45.4296) at a 40.6" (1280au) projected separation. We derive physical properties for COCONUTS-1B from (1) its near-infrared spectrum using cloudless Sonora atmospheric models, and (2) its luminosity and the white dwarf's age (7.3_-1.6_^+2.8^Gyr) using Sonora evolutionary models. The two methods give consistent temperatures and radii, but atmospheric models infer a lower surface gravity and therefore an unphysically young age. Assuming evolutionary model parameters (T_eff_=1255_-8_^+6^K, logg=5.44_-0.03_^+0.02^dex, R=0.789_-0.005_^+0.011^R_Jup_), we find that cloudless model atmospheres have brighter Y- and J-band fluxes than the data, suggesting that condensate clouds have not fully dispersed around 1300K. The W2 flux (4.6{mu}m) of COCONUTS-1B is fainter than models, suggesting non-equilibrium mixing of CO. To investigate the gravity dependence of the L/T transition, we compile all 60 known L6-T6 benchmarks and derive a homogeneous set of temperatures, surface gravities, and masses. As is well known, young, low-gravity late-L dwarfs have significantly fainter, redder near-infrared photometry and ~200-300K cooler temperatures than old, high-gravity objects. Our sample now reveals such gravity dependence becomes weaker for T dwarfs, with young objects having comparable near-infrared photometry and ~100K cooler temperatures compared to old objects. Finally, we find that young objects have a larger amplitude J-band brightening than old objects, and also brighten at H band as they cross the L/T transition.2020ApJ...891..171Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/891/171CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/mk : Catalogue of Stellar Spectral Classifications (Skiff, 2009-)III/42 : Selected MK Spectral Types (Jaschek, 1978)II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)II/343 : VIKING catalogue data release 2 (Edge+, 2016)II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)I/345 : Gaia DR2 (Gaia Collaboration, 2018)I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)II/364 : VIRAC. The VVV Infrared Astrometric Catalogue (Smith+, 2019)II/367 : The VISTA Hemisphere Survey (VHS) catalog DR5 (McMahon+, 2020)J/ApJS/99/135 : A-type stars rotation and spectral peculiarities (Abt+ 1995)J/ApJ/564/421 : Spectra of T dwarfs. I. 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(Gray+, 2006)J/AJ/132/891 : Binaries among nearby L dwarfs (Reid+, 2006)J/ApJS/167/40 : SDSS4 confirmed white dwarfs catalog (Eisenstein+, 2006)J/A+A/460/695 : Search for Associations Containing Young stars (Torres+, 2006)J/AJ/133/439 : Luminosity function of M7-L8 ultracool dwarfs (Cruz+, 2007)J/AJ/134/1162 : 11 new T dwarfs in 2MASS (Looper+, 2007)J/A+A/481/661 : Hyades brown dwarfs and very low mass stars (Bouvier+, 2008)J/AJ/136/1290 : Ultracool dwarfs from the 2MASS (Reid+, 2008)J/ApJ/689/1295 : Lithium test implications for BDs (Kirkpatrick+, 2008)J/ApJS/180/117 : MK classifications of spectroscopic binaries (Abt, 2009)J/ApJ/699/649 : Young M dwarfs within 25pc. I. (Shkolnik+, 2009)J/ApJ/710/1142 : SpeX spectroscopy of low mass binaries. I. (Burgasser+, 2010)J/MNRAS/403/1949 : UBV(RcIc)JHK photometry of HIP nearby stars (Koen+, 2010)J/A+A/522/A112 : i'z' photometry of L5 & later dwarf candidates (Reyle+, 2010)J/ApJ/730/128 : Spectroscopy of DA WD from the SDSS-DR4 (Tremblay+, 2011)J/A+A/530/A138 : Geneva-Copenhagen survey re-analysis (Casagrande+, 2011)J/A+A/535/A54 : HARPS search for extra-solar planets. XXIX (Segransan+, 2011)J/ApJ/752/56 : BDKP. III. Parallaxes for 70 ultracool dwarfs (Faherty+, 2012)J/ApJ/754/44 : The AstraLux Large M-dwarf Survey (Janson+ 2012)J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)J/MNRAS/430/1171 : Sub-stellar birth rate from UKIDSS (Day-Jones+, 2013)J/MNRAS/433/457 : 76 T dwarfs from the UKIDSS LAS (Burningham+, 2013)J/A+A/569/A120 : Spectra of wide companions to planet-host stars (Lodieu+ 2014)J/ApJ/792/119 : Companions to nearby stars from Pan-STARRS 1 (Deacon+, 2014)J/ApJ/794/125 : IN-SYNC. I. APOGEE stellar parameters (Cottaar+, 2014)J/ApJ/794/159 : Statistical analysis of exoplanet surveys (Brandt+, 2014)J/ApJS/214/17 : Orbital monitoring of AstraLux binaries (Janson+, 2014)J/A+A/577/A128 : CARMENES input catalog of M dwarfs. I (Alonso-Floriano+, 2015)J/MNRAS/449/3651 : L and T dwarfs from UKIDSS LAS (Marocco+, 2015)J/ApJ/810/158 : M,L,T dwarfs fundamental param. and SEDs (Filippazzo+, 2015)J/MNRAS/454/593 : Young moving groups in solar neighbourhood (Bell+, 2015)J/ApJ/814/118 : L/T dwarfs search with PS1 & WISE. II. (Best+, 2015)J/A+A/589/A21 : K-H_2_ line shapes for cool BDs spectra (Allard+, 2016)J/ApJS/225/10 : Kinematic analysis of M7-L8 dwarfs (Faherty+, 2016)J/ApJ/833/96 : Hawaii infrared plx program. II. Ultracool dwarfs (Liu+, 2016)J/ApJS/231/15 : Astrometric monitoring of ultracool dwarf bin. (Dupuy+, 2017)J/ApJ/848/11 : Spectroscopic and photometric analysis of WDs (Bedard+, 2017)J/ApJS/234/1 : Cat. of M, L, & T dwarfs from PS1 3{pi} Survey (Best+, 2018)J/AJ/156/18 : APOGEE binary comp. of evolved stars (Price-Whelan+, 2018)J/MNRAS/482/4570 : Gaia DR2 white dwarf candidates (Gentile Fusillo+, 2019)J/ApJ/878/63 : Cool WD atm. models. IV. Spectral evolution (Blouin+, 2019)J/AJ/158/13 : The first 300 stars observed by the GPIES (Nielsen+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/891/171https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/891/171http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/891/171https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/891/171https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/891/171http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/891/171GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/891/171/fig4UH/SNIFS & IRTF/SpeX spectra of COCONUTS-1ArecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSpSpectrum (1)meta.code;obsintlambda[3298.6/25414.2] Wavelength in Angstroms (2)0.1nmem.wldoubleFlux[-2.74e-16/4.9e-16] Flux in erg/cm2/s/{AA} unitscW.m**-2.nm**-1phot.fluxdoublee_Flux[1.96e-18/2.67e-16] Uncertainty in FluxcW.m**-2.nm**-1stat.error;phot.fluxdoubleJ/ApJ/891/171/fig6IRTF/SpeX 0.8 Prism spectra of COCONUTS-1BrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[0.68/2.54] Wavelength, Vacuumumem.wldoubleFlux[-2.86e-17/8.5e-17] Flux in erg/cm2/s/{AA} unitscW.m**-2.nm**-1phot.fluxdoublee_Flux[9e-19/4.91e-17] Uncertainty in FluxcW.m**-2.nm**-1stat.error;phot.fluxdouble