Infrared Spectroscopy of Brown Dwarfs: the onset of methane absorption in L dwarfs and the L/T transition

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dc.creatorGeballe, T. R.
dc.creatorNoll, K. S.
dc.creatorLeggett, S. K.
dc.creatorKnapp, G. R.
dc.creatorFan, X.
dc.creatorGolimowski, D
dc.date2001-02-03
dc.date.accessioned2026-07-07T01:57:36Z
dc.date.available2026-07-07T01:57:36Z
dc.descriptionWe present infrared spectra of brown dwarfs with spectral types from mid-L to T. The 0.9-2.5 $μ$m spectra of three dwarfs found by the Sloan Digital Sky Survey contain absorption bands of both methane and carbon monoxide and bridge the gap between late L and previously observed T dwarfs. These dwarfs form a clear spectral sequence, with CH$_{4}$ absorption increasing as the CO absorption decreases. Water vapor band strengths increase in parallel with the methane bands and thus also link the L and T types. We suggest that objects with detectable CO and CH$_{4}$ in the H and K bands should define the earliest T subclasses. From observations of bright (K~$\leq$~13 mag) L dwarfs found by 2MASS, we find that the onset of detectable amounts of CH$_{4}$ occurs near spectral type L5. For this spectral type methane is observable in the 3.3~$μ$m $ν$$_{3}$ band only, and not in the overtone and combination bands at H and K.
dc.description9 pages (Latex) and 5 figures (postscript). Proc of Mtg on Ultracool Dwarfs, Manchester, 12 August 2000, to be published in Lecture Notes in Physics (Heidelberg: Springer-Verlag)
dc.identifierhttps://arxiv.org/abs/astro-ph/0102059
dc.identifierhttp://arxiv.org/abs/astro-ph/0102059
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/2453
dc.subjectAstrophysics
dc.titleInfrared Spectroscopy of Brown Dwarfs: the onset of methane absorption in L dwarfs and the L/T transition
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