J/other/ARA+A/43ivo://CDS.VizieR/J/other/ARA+A/43.195CDSKirkpatrick J.D.2017-12-12T14:45:06Z2007-01-31T11:20:35ZCDS support team

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

cds-question@unistra.frdwarf-starsvisible-astronomytrigonometric-parallaxmorgan-keenan-classificationThe establishment of new spectral classes cooler than type M has had a brief, yet already rich, history. Prototypes of the new "L dwarf" and "T dwarf" classes were first found in the late 1980s to mid-1990s, with a flood of new discoveries occurring in the late 1990s with the advent of deep, large-area, digital sky surveys. Over four hundred and fifty L and T dwarfs are now catalogued. This review concentrates on the spectroscopic properties of these objects, beginning with the establishment of classification schemes rooted in the MK Process. The resulting grid of spectral types is then used as a tool to ferret out the underlying physics. The temperature ranges covered by these spectral types, the complex chemical processes responsible for the shape of their emergent spectra, their nature as either true stars or brown dwarfs, and their number density in the Galaxy are discussed. Two promising avenues for future research are also explored: the extension of the classification system to three dimensions to account for gravity- and metallicity-dependent features, and the capability of newer large-area surveys to uncover brown dwarfs cooler than those now recognized.2005ARA&A..43..195Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/other/ARA+A/43.195CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/239 : The Hipparcos and Tycho Catalogues (ESA 1997)J/AJ/123/3409 : SDSS M, L, and T dwarfs (Hawley+, 2002)J/ApJ/564/421 : Spectra of T dwarfs. I. (Burgasser+, 2002)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/other/ARA+A/43.195https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/other/ARA+A/43.195http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/other/ARA+A/43.195https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/other/ARA+A/43.195https://vizier.iucaa.in/viz-bin/votable?-source=J/other/ARA+A/43.195http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/other/ARA+A/43.195GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/other/ARA+A/43.195/table3 (L and T Dwarfs with Measured Trigonometric Parallaxes)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/other/ARA+A/43.195/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/other/ARA+A/43.195/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/other/ARA+A/43.195/table3?GETtext/xml+votable180.050000true1.1451667-40.73494440.0055555555555555566/439 496 858 4253 4316 4719 4775 4948 5413 5659 5718 6328 6613 6766 8361 8794 8995 9072 9569 10243 11719 11940 12541 12944 14850 16873 17166 17814 18032 18300 18683 18840 19747 19857 20896 21296 21861 22521 22681 22759 22861 24694 25015 25314 25934-25935 25945 26020 26196 26210 26248 26861 28277 28344 30956 31319 32337 32426 32457 35499 36072 36418 36602 42739 43966 44118 44286 44807 45564https://cdsarc.cds.unistra.fr/viz-bin/moc/J/other/ARA+A/43.195?format=asciiOpticaldefaultJ/other/ARA+A/43.195/table3L and T Dwarfs with Measured Trigonometric ParallaxesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameIR namemeta.id;meta.maincharplxTrigonometric parallax (2)maspos.parallax.trigfloate_plxrms uncertainty on plxmasstat.error;pos.parallaxfloatr_plxReference for plxmeta.bibintJmagJ magnitude (3)magphot.mag;em.IR.Jfloate_Jmagrms uncertainty on Jmagmagstat.error;phot.mag;em.IR.Jfloatr_JmagReference for Jmagmeta.bibintJMAGAbsolute J magnitude (3)magphys.magAbs;em.IR.Jfloate_JMAGrms uncertainty on JMAGmagstat.errorfloatdJmag? {Delta}J for binaries (3)magphot.mag;arith.difffloatnullableTG04? Temperature from Golimowski et al., 2004AJ....127.3516GKphys.temperatureintnullableTV04? Temperature from Vrba et al., 2004AJ....127.2948VKphys.temperatureintnullableTD02? Temperature from Dahn et al., 2002AJ....124.1170DKphys.temperatureintnullableSpType0Optical spectral type (6)src.spTyper_SpType0? Reference for SpType0meta.bibintnullableSpType1Infrared spectral type (6)src.spTyper_SpType1? Reference for SpType1meta.bibintnullableSpType2IR spectral type by Burgasser et al., 2002, Cat. <J/ApJ/564/421>src.spTypeONameOther namemeta.idcharSimbadSimbad column added by the CDScharRAJ2000Right ascension (J2000) (1)pos.eq.ra;meta.mainDEJ2000Declination (J2000) (1)pos.eq.dec;meta.mainJ/other/ARA+A/43.195/refsReferencesComCommentsmeta.notecharBibCodeBibCodemeta.bib.bibcodecharAutAuthor's namemeta.bib.authorcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference codemeta.noteint