HD 203030B: an Unusually Cool Young Sub-Stellar Companion near the L/T Transition

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dc.creatorMetchev, Stanimir A.
dc.creatorHillenbrand, Lynne A.
dc.date2006-07-21
dc.date.accessioned2026-07-07T10:39:38Z
dc.date.available2026-07-07T10:39:38Z
dc.descriptionWe present the discovery of a brown-dwarf companion to the 130-400 Myr-old G8 V star HD 203030. Separated by 11.9" (487 AU in projection) from its host star, HD 203030B has an estimated mass of 0.023 (+0.008;-0.011) solar masses. The K-band spectral type of L7.5+/-0.5 places HD 203030B near the critical L/T transition in brown dwarfs, which is characterized by the rapid disappearance of dust in sub-stellar photospheres. From a comparative analysis with well-characterized field L/T transition dwarfs, we find that, despite its young age, HD 203030B has a bolometric luminosity similar to the >1 Gyr-old field dwarfs. Adopting a radius from current models of sub-stellar evolution, we hence obtain that the effective temperature of HD 203030B is only 1206 (+74;-116) K, markedly lower than the ~1440 K effective temperatures of field L/T transition dwarfs. The temperature discrepancy can be resolved if either: (1) the ages of field brown dwarfs have been over-estimated by a factor of \~1.5, leading to under-estimated radii, or (2) the lower effective temperature of HD 203030B is related to its young age, implying that the effective temperature at the L/T transition is gravity-dependent.
dc.description16 pages, 4 figures, 2 tables. To appear in ApJ November 10, 2006, v651 issue
dc.identifierhttps://arxiv.org/abs/astro-ph/0607514
dc.identifierhttp://arxiv.org/abs/astro-ph/0607514
dc.identifierAstrophys.J.651:1166-1176,2006
dc.identifierdoi:10.1086/507836
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/181097
dc.subjectAstrophysics
dc.titleHD 203030B: an Unusually Cool Young Sub-Stellar Companion near the L/T Transition
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