From: LARRY KLAES (ljk4_at_msn.com)
Date: Mon Aug 15 2005 - 17:17:40 UTC
Paper: astro-ph/0508282
Date: Fri, 12 Aug 2005 09:09:23 GMT (245kb)
Title: A search for planetary-mass objects and brown dwarfs in the Upper
Scorpius association
Authors: M. T. Costado, V. J. S. Bejar, J. A. Caballero, R. Rebolo, J.
Acosta-Pulido, and A. Manchado
\Comments: 6 pages, 3 figures. A&A (accepted)
\\
We report the results of a deep photometric search for planets and brown
dwarfs in the nearby young OB Upper Scorpius association. We obtained
optical
(I) and near-infrared (JKs) images around nine very low-mass stars and brown
dwarf member candidates of the association, covering a total area of 113
arcmin^2. Using a point spread function subtraction technique, we have
searched
for planetary-mass companions (0.002 Msol < M < 0.013 Msol) at separations
as
close as 3 arcsec from the targets. We have not found any brown dwarfs more
massive than 0.030 Msol at projected distances larger than 70AU, or planets
more massive than 0.007 Msol at projected distances larger than 600AU. We
set
an upper limit of 20% (confidence level 68.3%) to the fraction of very
low-mass
stars and massive brown dwarfs with planetary mass companions (M > 0.007
Msol)
at physical distances larger than 600AU. From the I, I-J colour-magnitude
diagrams and follow-up Ks-band photometry, we identify four very red objects
(I-J > 2.5) in the area of the survey. According to their positions in the
diagram, below the expected theoretical sequence of the cluster, three are
probable late M-dwarfs in the field. The faintest and reddest object (J-Ks =
2.39 +/- 0.06) may be either a field intermediate L-dwarf with anomalously
red
J-Ks colour at a distance of approx. 135pc, an extremely red distant galaxy,
or
a reddened planetary-mass object in the Upper Scorpius association.
\\ ( http://arXiv.org/abs/astro-ph/0508282 , 245kb)
This archive was generated by hypermail 2.1.6 : Mon Aug 15 2005 - 17:26:22 UTC