Sixty-seven Additional L Dwarfs Discovered by the Two Micron All Sky Survey (2MASS)

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dc.creatorKirkpatrick, J. Davy
dc.creatorReid, I. Neill
dc.creatorLiebert, James
dc.creatorGizis, John E.
dc.creatorBurgasser, Adam J.
dc.creatorMonet, David G.
dc.creatorDahn, Conard C.
dc.creatorNelson, Brant
dc.creatorWilliams, Rik J.
dc.date2000-03-22
dc.date.accessioned2026-07-07T10:47:14Z
dc.date.available2026-07-07T10:47:14Z
dc.descriptionWe present JHKs photometry, far red spectra, and spectral classifications for an additional 67 L dwarfs discovered by the Two Micron All Sky Survey. One of the goals of this new search was to locate more examples of the latest L dwarfs. Of the 67 new discoveries, 17 have types of L6 or later. Analysis of these new discoveries shows that H-alpha emission has yet to be convincingly detected in any L dwarf later than type L4.5, indicating a decline or absence of chromospheric activity in the latest L dwarfs. Further analysis shows that 16 (and possibly 4 more) of the new L dwarfs are lithium brown dwarfs and that the average line strength for those L dwarfs showing lithium increases until roughly type L6.5 V then declines for later types. This disappearance may be the first sign of depletion of atomic lithium as it begins to form into lithium-bearing molecules. Another goal of the search was to locate nearer, brighter L dwarfs of all subtypes. Using absolute magnitudes for 17 L dwarf systems with trigonometric parallax measurements, we develop spectrophotometric relations to estimate distances to the other L dwarfs. Of the 67 new discoveries, 21 have photometric distances placing them within 25 parsecs of the Sun. A table of all known L and T dwarfs believed to lie within 25 parsecs - 53 in total - is also presented. Using the distance measurement of the coolest L dwarf known, we calculate that the gap in temperature between L8 and the warmest known T dwarfs is less than 350K and probably much less. If the transition region between the two classes spans a very small temperature interval, this would explain why no transition objects have yet been uncovered. This evidence, combined with model fits to low-resolution spectra of late-M and early-L dwarfs, indicates that L dwarfs span the range 1300K < Teff < 2000K.
dc.descriptionTo appear in AJ July 2000; 18 pages of text (LaTeX), 19 pages of figures (.jpg and .ps), 9 pages of tables (.ps and LaTeX); Tables 1 and 2 are in landscape mode
dc.identifierhttps://arxiv.org/abs/astro-ph/0003317
dc.identifierhttp://arxiv.org/abs/astro-ph/0003317
dc.identifierAstron.J.120:447,2000
dc.identifierdoi:10.1086/301427
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/183463
dc.subjectAstrophysics
dc.titleSixty-seven Additional L Dwarfs Discovered by the Two Micron All Sky Survey (2MASS)
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