J/ApJ/958/94ivo://CDS.VizieR/J/ApJ/958/94CDSRobbins G.Meisner A.M.Schneider A.C.Burgasser A.J.,Kirkpatrick J.D.Gagne J.Hsu C.-C.Moranta L.Casewell S.,Marocco F.Gerasimov R.Faherty J.K.Kuchner M.J.Caselden D.,Cushing M.C.Alejandro S.The Backyard Worlds: Planet 9 Collaboration,The Backyard Worlds: Cool Neighbors Collaboration2026-02-23T07:34:39Z2026-02-23T08:28:44ZCDS support team

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

cds-question@unistra.fry-dwarfsbrown-dwarfsinfrared-astronomyspectroscopyY dwarfs, the coolest known spectral class of brown dwarfs, overlap in mass and temperature with giant exoplanets, providing unique laboratories for studying low-temperature atmospheres. However, only a fraction of Y dwarf candidates have been spectroscopically confirmed. We present Keck/NIRES near-infrared spectroscopy of the nearby (d~6-8pc) brown dwarf CWISE J105512.11+544328.3. Although its near-infrared spectrum aligns best with the Y0 standard in the J band, no standard matches well across the full YJHK wavelength range. The CWISE J105512.11+544328.3 NH3-H=0.427+/-0.0012 and CH4-J=0.0385+/-0.0007 absorption indices and absolute Spitzer [4.5] magnitude of 15.18+/-0.22 are also indicative of an early-Y dwarf rather than a late-T dwarf. CWISE J105512.11+544328.3 additionally exhibits the bluest Spitzer [3.6]-[4.5] color among all spectroscopically confirmed Y dwarfs. Despite this anomalously blue Spitzer color given its low luminosity, CWISE J105512.11+544328.3 does not show other clear kinematic or spectral indications of low metallicity. Atmospheric model comparisons yield a log(g)<=4.5 and Teff~500+/-150K for this source. We classify CWISE J105512.11+544328.3 as a Y0 (pec) dwarf, adding to the remarkable diversity of the Y-type population. JWST spectroscopy would be crucial to understanding the origin of this Y dwarf's unusual preference for low-gravity models and blue 3-5{mu}m color.2023ApJ...958...94Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/958/94CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/328 : AllWISE Data Release (Cutri+ 2013)I/345 : Gaia DR2 (Gaia Collaboration, 2018)II/365 : The CatWISE2020 catalog (updated version 28-Jan-2021) (Marocco+, 2021)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/AJ/127/2856 : Brown dwarfs in the 2MASS Survey (Burgasser+, 2004)J/ApJ/637/1067 : Near-IR spectral classification of T dwarfs (Burgasser+, 2006)J/AJ/137/1 : PMs and astrometry of late-type dwarfs (Faherty+, 2009)J/ApJS/190/100 : NIR proper motion survey using 2MASS (Kirkpatrick+, 2010)J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)J/AJ/144/148 : Infrared phot. of brown dwarf and Hyper-LIRG (Griffith+, 2012)J/ApJ/753/156 : T/Y brown dwarfs with WISE photometry (Kirkpatrick+, 2012)J/ApJS/205/6 : T dwarf population revealed by WISE (Mace+, 2013)J/ApJ/794/143 : New SpeX Observations of M7-L6 Dwarfs (Bardalez+, 2014)J/ApJ/810/158 : M,L,T dwarfs fundamental param. and SEDs (Filippazzo+, 2015)J/ApJ/842/118 : Brown dwarfs with spectral type later than T6 (Leggett+, 2017)J/ApJ/856/23 : BANYAN. XI. The BANYAN {Sigma} algorithm (Gagne+, 2018)J/ApJS/240/19 : Parallaxes of late-T and Y dwarfs (Kirkpatrick+, 2019)J/ApJ/903/96 : The {mu}Tau Association (MUTA) (Gagne+, 2020)J/ApJ/889/74 : Spitzer follow-up of Y brown dwarfs (Meisner+, 2020)J/AJ/160/63 : IR sp. of 5 brown dwarfs with Gemini North IRS (Miles+, 2020)J/ApJ/920/20 : HST/WFC3 sp. of WISEP J182831.08+265037.8 (Cushing+, 2021)J/ApJS/253/7 : A full-sky census of BDs within 20pc (Kirkpatrick+, 2021)J/ApJ/918/11 : Infrared photometry of late-type brown dwarfs (Leggett+, 2021)J/ApJ/939/94 : New assoc. in Gaia DR3 solar neighborhood (Moranta+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/958/94https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/958/94http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/958/94https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/958/94https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/958/94http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/958/94GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap1.3088508223161842e-20 1.7003137259100215e-19InfrareddefaultJ/ApJ/958/94/table1WISE J105512.11+544328.3 properties and photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintpmRA[-1518.7] Proper motion in right ascension direction (pmRA*cosDE) (1)mas/yrpos.pm;pos.eq.rafloate_pmRA[2.1] pmRA uncertaintymas/yrstat.error;pos.pm;pos.eq.rafloatpmDE[-222.7] Proper motion in declination direction (1)mas/yrpos.pm;pos.eq.decfloate_pmDE[2] pmDE uncertaintymas/yrstat.error;pos.pm;pos.eq.decfloatmuTot[1534.9] Total proper motion (1)mas/yrpos.pmfloate_muTot[2.9] muTot uncertaintymas/yrstat.error;pos.pmfloatplx[145] Parallax (1)maspos.parallax.trigfloate_plx[14.7] Parallax uncertaintymasstat.error;pos.parallaxfloatVtan[50.2] Tangential velocity; this workkm/sphys.veloc.transversefloate_Vtan[5.2] Vtan uncertaintykm/sstat.error;phys.veloc.transversefloatSpTSpectral type; this worksrc.spTypechare_SpT[0.5] SpT uncertaintystat.error;src.spTypefloatTeff[500] Effective temperature; this workKphys.temperature.effectiveinte_Teff[150] Teff uncertaintyKstat.error;phys.temperature.effectiveintl_logg[<=] Limit flag on loggmeta.code.errorcharloggLog of surface gravity; this worklog(cm.s**-2)phys.gravityfloatJMKO[18.868] MKO J-band magnitude; this work (see Section 2.2)magphot.mag;em.IR.Jfloate_JMKO[0.066] JMKO uncertaintymagstat.error;phot.mag;em.IR.Jfloatl_JmagLimit flag on Jmagmeta.code.errorcharJmagJ-band magnitude (1)magphot.mag;em.IR.Jfloatl_HmagLimit flag on Hmagmeta.code.errorcharHmagH-band magnitude (1)magphot.mag;em.IR.Hfloatl_KsmagLimit flag on Ksmagmeta.code.errorcharKsmagKs-band magnitude (1)magphot.mag;em.IR.KfloatW1catW[17.332] CatWISE (II/365) W1 magnitudemagphot.mag;em.IR.3-4umfloate_W1catW[0.082] W1catW uncertaintymagstat.error;phot.mag;em.IR.3-4umfloatW2catW[14.371] CatWISE (II/365) W2 magnitudemagphot.mag;em.IR.4-8umfloate_W2catW[0.018] W2catW uncertaintymagstat.error;phot.mag;em.IR.4-8umfloatW1mag[17.306] AllWISE W1 (3.4um) band magnitudemagphot.mag;em.IR.3-4umfloate_W1mag[0.127] Uncertainty on the W1magmagstat.error;phot.mag;em.IR.3-4umfloatW2mag[14.366] AllWISE W2 (4.6um) band magnitudemagphot.mag;em.IR.4-8umfloate_W2mag[0.044] Uncertainty on the W2magmagstat.error;phot.mag;em.IR.4-8umfloatW3mag[11.553] AllWISE W3 (12um) band magnitudemagphot.mag;em.IR.8-15umfloate_W3mag[0.196] Uncertainty on the W3magmagstat.error;phot.mag;em.IR.8-15umfloatch1mag[16.219] Spitzer ch1 (3.6um) band magnitude (1)magphot.mag;em.IR.3-4umfloate_ch1mag[0.033] Uncertainty on the ch1magmagstat.error;phot.magfloatch2mag[14.376] Spitzer ch2 (4.5um) band magnitude (1)magphot.mag;em.IR.4-8umfloate_ch2mag[0.019] Uncertainty on the ch2magmagstat.error;phot.magfloatFileName of the FITS file in subdirectory "sp"meta.id;meta.fitscharfitsDownload the FITS filemeta.ref.urlchar