A young very low-mass object surrounded by warm dust
L. Testi, A. Natta et al.
We present a complete low-resolution (R~100) near-infrared spectrum
of the substellar object GY11, member of the rho-Ophiuchi young association.
The object is remarkable because of its low estimated mass and age and because
associated with a mid-infrared source, an indication of a surrounding
dusty disk. Based on the comparison of our spectrum with similar spectra
of field M-dwarfs and atmospheric models,
we obtain revised estimates of the
spectral type, effective temperature and luminosity of the central object.
These parameters are used to place the object on a Hertzprung-Russell diagram
and to compare with the prediction of pre-main sequence evolutionary models.
Our analysis suggests that the central object has a
very low mass, probably below the deuterium burning limit and in the
range 8-12MJupiter, and a young age, less than 1Myr.
The infrared excess is shown to be consistent with the emission of a flared,
similar to those found in more massive brown dwarf and TTauri
systems. This result suggests that substellar objects,
even the so-called isolated planetary
mass objects, found in young stellar associations are produced in a similar
fashion as stars, by core contraction and gravitational