Discovery of a nearby L-T transition object in the Southern Galactic plane

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dc.creatorFolkes, Stuart L.
dc.creatorPinfield, David J.
dc.creatorKendall, Tim R.
dc.creatorJones., Hugh R. A.
dc.date2007-03-30
dc.date.accessioned2026-07-07T11:01:20Z
dc.date.available2026-07-07T11:01:20Z
dc.descriptionWe present the discovery of 2MASS J11263991-5003550 identified as part of an ongoing survey to discover ultra-cool dwarfs in the Southern Galactic Plane, using data from the 2MASS and SuperCOSMOS Sky Surveys. Strong FeH and H2O absorption features in the near-infrared JH-band spectrum reveal characteristics seen in both mid-L, and L-T transition type dwarfs. We suggest these may be attributable to holes in the condensate cloud layers in the atmosphere of a single sub-stellar object, but cannot at present completely rule out the role of binarity as the possible cause. We also identify this object as a blue L dwarf, and explore the similar observable characteristics of these objects with those of the L-T transition. From this comparison we suggest that the temperature (and thus spectral type) at which the condensate cloud later begins to break-up/rain out, may be highly sensitive to small variations in metallicity. However, the JH-band spectrum of this object does not resemble that of the known L sub-dwarfs, and therefore extreme metal deficiency may not in fact be responsible for the discordant features. We estimate a spectral type of L9+/-1, and measure a large proper-motion of μ_(tot)=1.65"+/-0.03" per year. Also, a spectrophotometric distance of 8.2pc is estimated, possibly making this object the nearest easily observable single L-T transition object in the southern hemisphere.
dc.description10 pages with 7 figures, and 3 tables. LaTeX. Accepted for publication by MNRAS
dc.identifierhttps://arxiv.org/abs/astro-ph/0703808
dc.identifierhttp://arxiv.org/abs/astro-ph/0703808
dc.identifierMon.Not.Roy.Astron.Soc.378:901-909,2007
dc.identifierdoi:10.1111/j.1365-2966.2007.11789.x
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/187921
dc.subjectAstrophysics
dc.titleDiscovery of a nearby L-T transition object in the Southern Galactic plane
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