J/ApJ/943/L16ivo://CDS.VizieR/J/ApJ/943/L16doi:10.26093/cds/vizier.19439016CDSSchneider A.C.Burgasser A.J.Bruursema J.Munn J.A.Vrba F.J.,Caselden D.Kabatnik M.Rothermich A.Sainio A.Bickle T.P.,Dahm S.E.Meisner A.M.Kirkpatrick J.D.Suarez G.Gagne J.,Faherty J.K.Vos J.M.Kuchner M.J.Williams S.J.Gagliuffi D.B.,Aganze C.Hsu C.-C.Theissen C.Cushing M.C.Marocco F.Casewell S.,(The Backyard Worlds: Planet 9 Collaboration)2025-05-21T20:14:39Z2025-02-04T14:47:45ZCDS support team

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

cds-question@unistra.frbrown-dwarfsinfrared-astronomyspectroscopyWe present the discovery of CWISE J050626.96+073842.4 (CWISEJ0506+0738), an L/T transition dwarf with extremely red near-infrared colors discovered through the Backyard Worlds: Planet 9 citizen science project. Photometry from UKIRT and CatWISE give a (J-K)_MKO_ color of 2.97+/-0.03mag and a J_MKO_-W2 color of 4.93+/-0.02mag, making CWISE J0506+0738 the reddest known free-floating L/T dwarf in both colors. We confirm the extremely red nature of CWISE J0506+0738 using Keck/NIRES near-infrared spectroscopy and establish that it is a low-gravity, late-type L/T transition dwarf. The spectrum of CWISE J0506+0738 shows possible signatures of CH4 absorption in its atmosphere, suggesting a colder effective temperature than other known, young, red L dwarfs. We assign a preliminary spectral type for this source of L8{gamma}-T0{gamma}. We tentatively find that CWISE J0506+0738 is variable at 3-5{mu}m based on multiepoch WISE photometry. Proper motions derived from follow-up UKIRT observations combined with a radial velocity from our Keck/NIRES spectrum and a photometric distance estimate indicate a strong membership probability in the {beta} Pic moving group. A future parallax measurement will help to establish a more definitive moving group membership for this unusual object.2023ApJ...943L..16Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/943/L16CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)II/367 : The VISTA Hemisphere Survey (VHS) catalog DR5 (McMahon+, 2020)II/365 : The CatWISE2020 catalog (updated version 28-Jan-2021) (Marocco+, 2021)J/other/ARA+A/43.195 : L and T dwarf stars (Kirkpatrick, 2005)J/ApJ/637/1067 : NIR spectral classification of T dwarfs (Burgasser+, 2006)J/AJ/132/891 : Binaries among nearby L dwarfs (Reid+, 2006)J/AJ/134/1162 : 11 new T dwarfs in 2MASS (Looper+, 2007)J/ApJ/689/1295 : Lithium test implications for BDs (Kirkpatrick+, 2008)J/ApJ/676/1281 : L and T dwarfs in 2MASS/SDSS (Metchev+, 2008)J/ApJ/723/684 : NIRSPEC ultracool dwarf RVel survey (Blake+, 2010)J/ApJS/190/100 : NIR proper motion survey using 2MASS (Kirkpatrick+, 2010)J/A+A/517/A76 : Near-IR spectrum of 2M1207b (Patience+, 2010)J/ApJ/743/156 : NEOWISE obs. of NEOs: preliminary results (Mainzer+, 2011)J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)J/ApJS/205/6 : T dwarf population revealed by WISE (Mace+, 2013)J/PASP/125/809 : New nearby M, L, and T dwarfs (Thompson+, 2013)J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)J/A+A/564/A55 : 1.1-2.4um sp. of 7 young M and L dwarfs (Manjavacas+, 2014)J/AJ/147/20 : Spectroscopy of 447 nearby M dwarfs (Newton+, 2014)J/AJ/147/34 : SpeX library of L-type dwarfs (Schneider+, 2014)J/MNRAS/454/593 : Young moving groups in solar neighbourhood (Bell+, 2015)J/ApJ/814/118 : L/T transition dwarfs with PS1 & WISE. II. (Best+, 2015)J/ApJ/810/158 : M,L,T dwarfs fundamental param. and SEDs (Filippazzo+, 2015)J/ApJS/219/33 : BANYAN. VII. Candidate YMG members from BASS (Gagne+, 2015)J/ApJ/814/65 : Jupiter HST light curves (Karalidi+, 2015)J/other/Sci/350.64 : 51 Eri b near-infrared spectrum (Macintosh+, 2015)J/ApJS/225/10 : Kinematic analysis of M7-L8 dwarfs (Faherty+, 2016)J/ApJ/833/96 : Hawaii infrared parallax program. II. (Liu+, 2016)J/ApJ/817/112 : NEOWISE/AllWISE high PM objects (Schneider+, 2016)J/AJ/153/95 : Catalog of Suspected Nearby Young Stars (Riedel+, 2017)J/AJ/154/69 : ACRONYM II. {beta} Pictoris Moving Group (Shkolnik+, 2017)J/AJ/155/34 : The NIR spectra of neighboring L dwarfs (Cruz+, 2018)J/ApJ/856/23 : BANYAN. XI. The BANYAN {Sigma} algorithm (Gagne+, 2018)J/AJ/159/257 : Hawaii IR parallax program. IV. L0-T8 BDs (Best+, 2020)J/A+A/642/A179 : beta Pic moving group RV of 81 stars (Miret-Roig+, 2020)J/AJ/160/38 : Spitzer variability detections of 79 BDs (Vos+, 2020)J/ApJ/891/171 : COCONUTS. I. Sp. of a WD & T4 comoving syst. (Zhang+, 2020)J/AJ/161/42 : Volume-limited sample of cool dwarfs. I. (Best+, 2021)J/ApJ/923/48 : An L dwarf co-moving BD+60 1417 (Faherty+, 2021)J/ApJS/257/45 : BDKP. V. Radial & rot. vel. of M, L, T dwarfs (Hsu+, 2021)J/ApJS/253/7 : A full-sky census of BDs within 20pc (Kirkpatrick+, 2021)J/ApJ/934/178 : L/T transition BDs from NIR SpeX spectra (Ashraf+, 2022)J/AJ/163/288 : Astrometry for {epsilon} Indi B (Chen+, 2022)J/MNRAS/513/5701 : Silicate clouds in ultracool dwarfs (Suarez+, 2022)J/AJ/164/239 : IR LC of VHS1256-1257b in 2018 & 2020 epochs (Zhou+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/943/L16https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/943/L16http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/943/L16https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/943/L16https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/943/L16http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/943/L16GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfrareddefaultJ/ApJ/943/L16/fig2The Keck/NIRES spectrum of CWISE J0506+0738recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[0.96/2.5] Wavelengthumem.wldoubleFlux[-1.8e-16/1.5e-16] Flux; erg/s/cm^2^/AngstromcW.m**-2.nm**-1phot.fluxdoublee_Flux[8.7e-20/4.4e-17] Uncertainty in FluxcW.m**-2.nm**-1stat.error;phot.fluxdouble