J/AJ/167/168ivo://CDS.VizieR/J/AJ/167/168doi:10.26093/cds/vizier.51670168CDSManjavacas E.Tremblin P.Birkmann S.Valenti J.Alves de Oliveira C.,Beck T.L.Giardino G.Lutzgendorf N.Rauscher B.J.Sirianni M.2024-11-06T20:19:40Z2024-07-01T09:10:33ZCDS support team

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

cds-question@unistra.frl-dwarfsm-starsinfrared-astronomyspectroscopySpectra of young benchmark brown dwarfs with well-known ages are vital to characterize other brown dwarfs, for which ages are in general not known. These spectra are also crucial to test atmospheric models, which have the potential to provide detailed information about the atmospheres of these objects. However, to test atmospheric models optimally, medium-resolution, long-wavelength-coverage spectra with well-understood uncertainties are ideal, such as the spectra provided by the NIRSpec instrument on board the James Webb Space Telescope. In this paper, we present medium-resolution JWST/NIRSpec spectra of two young brown dwarfs, TWA 28 (M9.0) and TWA 27A (M9.0), and one planetary-mass object, TWA 27B (L6.0), members of the TW Hydrae Association (age ~10Myr). We show the richness of the atomic lines and molecular bands present in the spectra. All objects show signs of a circumstellar disk, via a near-infrared excess and/or via emission lines. We matched a set of cloudless atmospheric spectra (ATMO), and cloudy atmospheric spectra (BT-Settl) to our NIRSpec spectra, and analyzed which wavelength ranges and spectral features both models reproduce best. Both models derive consistent parameters for the three sources, and predict the existence of CH4 at 3.35{mu}m in TWA 27B. Nonetheless, in contrast to other slightly older objects with similar spectral type, like PSO 318.5-22 and VHS 1256b, this feature is not present in the spectrum of TWA 27B. The lack of the CH4 feature might suggest that the L-T transition of very young dwarfs starts at later spectral types than for older brown dwarfs.2024AJ....167..168Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/167/168CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/562/A127 : NIR integral field spectra of 15 M-L dwarfs (Bonnefoy+, 2014)J/A+A/564/A55 : 1.1-2.4um spectra of 7 young M & L dwarfs (Manjavacas+, 2014)J/ApJS/225/10 : Kinematic analysis of M7-L8 dwarfs (Faherty+, 2016)J/ApJ/831/125 : ALMA 887um obs. of ChaI star-forming region (Pascucci+, 2016)J/ApJ/818/176 : HST/WFC3 NIR photometry of 2M1207b (Zhou+, 2016)J/A+A/602/A33 : X-Shooter spectroscopy of YSOs in Lupus (Frasca+, 2017)J/ApJ/838/73 : Brown dwarf surface gravities Keck/NIRSPEC (Martin , 2017)J/AJ/157/101 : Cloud Atlas: HST/WFC3 NIR spectral library (Manjavacas+, 2019)J/A+A/632/A46 : TW Hydrae association with X-shooter (Venuti+, 2019)J/AJ/165/269 : TW Hya association candidate members (Luhman, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/167/168https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/167/168http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/167/168https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/167/168https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/167/168http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/167/168GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfrareddefaultJ/AJ/167/168/wasp27aCombined table from original tablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWaveWavelength observedumem.wldoubleFlux? FluxJyphot.flux.density;em.IRdoublenullablee_Flux? Error on FluxJystat.error;phot.fluxdoublenullableJ/AJ/167/168/wasp27bCombined table from original tablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWaveWavelength observedumem.wldoubleFlux? FluxJyphot.flux.density;em.IRdoublenullablee_Flux? Error on FluxJystat.error;phot.fluxdoublenullableJ/AJ/167/168/wasp28Combined table from original tablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWaveWavelength observedumem.wldoubleFlux? FluxJyphot.flux.density;em.IRdoublenullablee_Flux? Error on FluxJystat.error;phot.fluxdoublenullable