J/ApJ/898/77ivo://CDS.VizieR/J/ApJ/898/77doi:10.26093/cds/vizier.18980077CDSSchneider A.C.Burgasser A.J.Gerasimov R.Marocco F.Gagne J.,Goodman S.Beaulieu P.Pendrill W.Rothermich A.Sainio A.,Kuchner M.J.Caselden D.Meisner A.M.Faherty J.K.Mamajek E.E.,Hsu C.-C.Greco J.J.Cushing M.C.Kirkpatrick J.D.,Bardalez-Gagliuffi D.Logsdon S.E.Allers K.Debes J.H.2022-03-21T08:47:02Z2021-12-13T11:07:36ZCDS support team

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

cds-question@unistra.frinfrared-astronomyspectroscopyt-dwarfsbrown-dwarfsWe present the discoveries of WISEAJ041451.67-585456.7 and WISEAJ181006.18-101000.5, two low-temperature (1200-1400K), high proper motion T-type subdwarfs. Both objects were discovered via their high proper motion (>0.5yr^-1^); WISEA J181006.18-101000.5 as part of the NEOWISE proper motion survey and WISEA J041451.67-585456.7 as part of the citizen science project Backyard Worlds; Planet 9. We have confirmed both as brown dwarfs with follow-up near-infrared spectroscopy. Their spectra and near-infrared colors are unique among known brown dwarfs, with some colors consistent with L-type brown dwarfs and other colors resembling those of the latest-type T dwarfs. While no forward model consistently reproduces the features seen in their near-infrared spectra, the closest matches suggest very low metallicities ([Fe/H]<=-1), making these objects likely the first examples of extreme subdwarfs of the T spectral class (esdT). WISEAJ041451.67-585456.7 and WISEA J181006.18-101000.5 are found to be part of a small population of objects that occupy the "substellar transition zone", and have the lowest masses and effective temperatures of all objects in this group.2020ApJ...898...77Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/898/77CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/328 : AllWISE Data Release (Cutri+ 2013)II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)J/AJ/113/806 : M-Subdwarfs (Gizis 1997)J/A+A/410/527 : Abundances in the Galactic disk (Bensby+, 2003)J/AJ/134/1162 : 11 new T dwarfs in 2MASS (Looper+, 2007)J/AJ/137/1 : PMs and astrometry of late-type dwarfs (Faherty+, 2009)J/A+A/493/L27 : Parallaxes of 10 ultracool subdwarfs (Schilbach+, 2009)J/ApJS/190/100 : NIR proper motion survey using 2MASS (Kirkpatrick+, 2010)J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)J/MNRAS/433/457 : 76 T dwarfs from the UKIDSS LAS (Burningham+, 2013)J/MNRAS/430/1171 : Sub-stellar birth rate from UKIDSS (Day-Jones+, 2013)J/ApJ/783/122 : AllWISE motion survey (Kirkpatrick+, 2014)J/ApJ/787/126 : WISE reduced PMs and spectral types (Luhman+, 2014)J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)J/ApJ/810/158 : M,L,T dwarfs fundamental param. and SEDs (Filippazzo+, 2015)J/MNRAS/449/3651 : L and T dwarfs from UKIDSS LAS (Marocco+, 2015)J/ApJS/224/36 : The AllWISE motion survey (AllWISE2) (Kirkpatrick+, 2016)J/ApJ/817/112 : NEOWISE/AllWISE high PM objects (Schneider+, 2016)J/AJ/155/34 : Analysis of neighboring L dwarfs NIR spectra (Cruz+, 2018)J/AJ/158/182 : Discoveries from the NEOWISE PM survey (Greco+, 2019)J/A+A/628/A61 : X-shooter spectra of 43 metal-poor M dwarfs (Lodieu+, 2019)J/ApJS/240/31 : M-subdwarf research. I. LAMOST DR4 spectra (Zhang+, 2019)J/ApJ/889/176 : Very low-mass binaries with Gaia DR2 data (Faherty+, 2020)J/ApJ/889/74 : Spitzer follow-up of Y brown dwarfs (Meisner+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/898/77https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/898/77http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/898/77https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/898/77https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/898/77http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/898/77GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfrareddefaultJ/ApJ/898/77/w0414Near-infrared spectra of WISEA J041451.67-585456.7recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[0.77/2.53] Wavelengthumem.wldoubleFluxl[-4.66e-14/1.96e-13] Flux (lambda*Flambda) in erg/cm2/s/{AA} unitscW.m**-2.nm**-1meta.unit;phot.fluxdoublee_Fluxl[1.05e-22/2.43e-13] Uncertainty in FluxlcW.m**-2.nm**-1stat.errordoubleJ/ApJ/898/77/w1810Near-infrared spectra of WISEA J181006.18-101000.5recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[0.97/2.47] Wavelengthumem.wldoubleFluxl[-5.55e-16/6.38e-16] Flux (lambda*Flambda) in erg/cm2/s/{AA} unitscW.m**-2.nm**-1meta.unit;phot.fluxdoublee_Fluxl[2.97e-18/5.24e-16] Uncertainty in FluxlcW.m**-2.nm**-1stat.errordouble