Cool Stars 14 - Submitted Abstract # 403
This version created on 23 October 2006

On the circumstellar environment of brown dwarfs in Taurus


S. Guieu
C. Pinte
J.-L. Monin
F. Menard
M. Fukagawa
D. Padgett
A. Noriega-Crespo
S. Carey
L. Rebull
T. Huard

We study the presence of disks around BDs in the Taurus cloud,
and discuss  implications for substellar formation models.  We
use photometric measurements from the visible domain to the
Spitzer far  infrared to determine the Spectral Energy
Distribution of Taurus BD, plus model  fitting of these
distributions and colors. 

We compute color indexes and determine disk models fits to
estimate the  physical parameters of the disks around BD. We
find that ? 50% of all BDs have  a disk but BD with and without
disks are not distributed regularly across the  Taurus cloud.
Conclusions. We find that 48%+/- 17% of Taurus BDs have a 
circumstellar disk signature, a ratio similar to recent results
from previous  authors in other regions . We fit the BDs SED and
find that none of the disks  around BDs in Taurus can be fitted
convincingly with a flaring index beta = 0.  indicating that the
disks we observe retain a significant amount of gas. We  find
that BD with disks are proportionally more numerous in one of
the Taurus  filaments, the northern one, possibly the youngest.
We do not find the same  segregation for CTTS and WTTS,
suggesting that superimposed on the evolution  effect, the
segregation effect is related to the mass of the objects. A 
by-product of our study is to propose a recalibration of the
Barrado y  Navascues & Martin (2003) accretion limit in the
substellar domain. The global  shape of the limit fits our data
points if it is raised by a factor 1.25-1.30. 

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