SETI public: Discovery of a Planetary-Mass Brown Dwarf with a Circumstellar Disk

• Previous message: LARRY KLAES: "SETI public: FW: Latest News from the Astrobiology Magazine"

Paper: astro-ph/0511807
Date: Tue, 29 Nov 2005 21:32:34 GMT (27kb)

Title: Discovery of a Planetary-Mass Brown Dwarf with a Circumstellar Disk

Authors: K. L. Luhman, Lucia Adame, Paola D'Alessio, Nuria Calvet, Lee
Hartmann, S. T. Megeath, and G. G. Fazio

Comments: 5 pages, accepted to Astrophysical Journal Letters
\\
Using the Hubble Space Telescope, the 4 m Blanco telescope at the Cerro
Tololo Inter-American Observatory, and the Spitzer Space Telescope, we have
performed deep imaging from 0.8 to 8 um of the southern subcluster in the
Chamaeleon I star-forming region. In these data, we have discovered an
object,
Cha 110913-773444, whose colors and magnitudes are indicative of a very
low-mass brown dwarf with a circumstellar disk. In a near-infrared spectrum
of
this source obtained with the Gemini Near-Infrared Spectrograph, the
presence
of strong steam absorption confirms its late-type nature (>=M9.5) while the
shapes of the H- and K-band continua and the strengths of the Na I and K I
lines demonstrate that it is a young, pre-main-sequence object rather than a
field dwarf. A comparison of the bolometric luminosity of Cha 110913-773444
to
the luminosities predicted by the evolutionary models of Chabrier and
Baraffe
and Burrows and coworkers indicates a mass of 8+7/-3 M_Jup, placing it fully
within the mass range observed for extrasolar planetary companions (M<=15
M_Jup). The spectral energy distribution of this object exhibits
mid-infrared
excess emission at >5 um, which we have successfully modeled in terms of an
irradiated viscous accretion disk with M'<=10e-12 M_sun/year. Cha
110913-773444
is now the least massive brown dwarf observed to have a circumstellar disk,
and
indeed is one of the least massive free-floating objects found to date.
These
results demonstrate that the raw materials for planet formation exist around
free-floating planetary-mass bodies.

\\ ( http://arXiv.org/abs/astro-ph/0511807 , 27kb)

• Previous message: LARRY KLAES: "SETI public: FW: Latest News from the Astrobiology Magazine"

This archive was generated by hypermail 2.1.6 : Thu Dec 01 2005 - 06:43:48 PST