J/MNRAS/513/5701ivo://CDS.VizieR/J/MNRAS/513/5701doi:10.26093/cds/vizier.75135701CDSSuarez G.Metchev S.2024-08-22T20:15:33Z2022-09-19T14:02:43ZCDS support team

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

cds-question@unistra.frdwarf-starsinfrared-astronomyspectroscopymillimeter-astronomyphotometrysubmillimeter-astronomyWe present a uniform analysis of all mid-infrared R~90 spectra of field M5-T9 dwarfs obtained with the Spitzer Infrared Spectrograph (IRS). The sample contains 113 spectra out of which 12 belong to late-M dwarfs, 69 to L dwarfs, and 32 to T dwarfs. Sixty-eight of these spectra are presented for the first time. We measure strengths of the main absorption bands in the IRS spectra, namely water at 6.25um, methane at 7.65um, ammonia at 10.5um, and silicates over 8-11um. Water absorption is present in all spectra and strengthens with spectral type. The onset of methane and ammonia occurs at the L8 and T2.5 types, respectively, although ammonia can be detectable as early as T1.5. Silicate absorption sets in at spectral type L2, is on average the strongest in L4-L6 dwarfs, and disappears past L8. However, silicate absorption can also be absent from the spectra at any L subtype. We find a positive correlation between the silicate absorption strength and the excess (deviation from median) near-infrared colour at a given L subtype, which supports the idea that variations of silicate cloud thickness produce the observed colour scatter in L dwarfs. We also find that variable L3-L7 dwarfs are twice more likely to have above-average silicate absorption than non-variables. The ensemble of results solidifies the evidence for silicate condensate clouds in the atmospheres of L dwarfs, and for the first time observationally establishes their emergence and sedimentation between effective temperatures of ~2000K and ~1300K, respectively.2022MNRAS.513.5701Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/513/5701CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/513/5701https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/513/5701http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/513/5701https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/513/5701https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/513/5701http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/513/5701GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/513/5701/tables (Objects with IRS spectra (tables 1, 2, 4 and 5 of the paper))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/513/5701/tables?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/513/5701/tables?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/513/5701/tables?GETtext/xml+votable180.050000true0.056325.90550.0055555555555555566/2789 3965 4316 4719 4775 4948 5000 5077 5200 5413 5560 5666 6047 6072 6261 6328 6613 6629 7220 7369 7440 7533 7985 8348 8402 8625 8783 8794 9009 9063 9072 9173 9449 9467 9479 9569 11164 11292 11719 11940 12579 12592 13425 13885 15085 16609 17530 18017 18060 18067 18156 18281 18450 18683 19050 19144 19369 19857 20141 20273 21209 21296 21861 22521 22681 22759 22861 22937 23471 24694 25100 25558 25853 26210 26248 26564 26667 26861 27019 27058 27074 27618 27653 27698 30505 31009 31309 31319 31863 31871 32650 33767 34622 34660 34780 35499 36526 36845 38176 38683 39482 40228 40332 41984 43475 43966 44226 44284 44807 44954 45564 47192 491391.3088508223161842e-20 2.1279058820884434e-20https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/513/5701?format=asciiInfraredMillimeterdefaultJ/MNRAS/513/5701/tablesObjects with IRS spectra (tables 1, 2, 4 and 5 of the paper)MethaneMethane index valuespect.indexfloatBinaryReference to binaritymeta.bibcharWater? Water index valuespect.indexfloatnullablee_Water? Water index value errorstat.errorfloatnullablee_MethaneMethane index value errorstat.errorfloatAmmoniaAmmonia index valuespect.indexfloate_AmmoniaAmmonia index value errorstat.errorfloatSilicate? Silicate index valuespect.indexfloatnullablee_Silicate? Silicate index value errorstat.errorfloatnullableVariableReference to variabilitymeta.bibcharNon-varReference to no variabilitymeta.bibcharAORKEYAstronomical observation request keymeta.id;obscharModuleIRS spectroscopic modulemeta.id;instrcharExpTimeExposure time in each moduletime.duration;obs.exposurecharPIProgram PImeta.notecharPublicationPublication reference (1)meta.bibcharSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintspShow the spectrummeta.ref.urlcharNameName of IRS targetsmeta.id;meta.maincharSNameShort name of IRS targetsmeta.idcharOName? Alternative name of IRS targetsmeta.idcharRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainDiscoveryDiscovery referencemeta.bibcharSpTypeoptOptical spectral typesrc.spTypecharr_SpTypeoptOptical spectral type referencemeta.ref;pos.framecharSpTypeirInfrared spectral typesrc.spTypecharr_SpTypeirInfrared spectral type referencemeta.ref;pos.framecharProgramProgram IDmeta.id;obsintSNR6um? Signal-to-noise ration at 6 umstat.snrintnullableSNR12um? Signal-to-noise ration at 12 umstat.snrintnullableCH4obs? Observed IRAC [8.0] magnitudemagphot.flux.density;em.IR.8-15umfloatnullablee_CH4obs? Observed IRAC [8.0] magnitude errormagstat.errorfloatnullableW3obs? Observed WISE W3 magnitude (2)magphot.flux.density;em.IR.8-15umfloatnullablee_W3obs? Observed WISE W3 magnitude error (2)magstat.errorfloatnullableCH4syn? Synthetic IRAC [8.0] magnitude (3)magphot.flux.density;em.IR.8-15umfloatnullablee_CH4syn? Synthetic IRAC [8.0] magnitude errormagstat.errorfloatnullableW3syn? Synthetic WISE W3 magnitude (3)magphot.flux.density;em.IR.8-15umfloatnullablee_W3syn? Synthetic WISE W3 magnitude errormagstat.errorfloatnullableObsDateObserving datetime.epochcharr_CH4obs? Observed IRAC [8.0] magnitude referencemeta.ref;pos.framecharJ/MNRAS/513/5701/refsReferencesRefReference codemeta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBibCodeBibCodemeta.bib.bibcodecharAutAuthor's namemeta.bib.authorcharComCommentsmeta.notechar