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Summary: ccsd-00090709,version1-1Sep2006 Astronomy & Astrophysics manuscript no. 5425.hyper26874 c ESO 2006
September 1, 2006
A U-band survey of brown dwarfs in the Taurus Molecular Cloud
with the XMM-Newton Optical/UV Monitor
N. Grosso1, M. Audard2, J. Bouvier1, K. R. Briggs3, and M. G¨udel3
1
Laboratoire d'Astrophysique de Grenoble, Universit´e Joseph-Fourier, F-38041 Grenoble cedex 9, France
e-mail: Nicolas.Grosso@obs.ujf-grenoble.fr
2
Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027, USA
3
Paul Scherrer Institut, 5232 Villigen und W¨urenlingen, Switzerland
Received 12 April 2006 / Accepted 16 June 2006
ABSTRACT
Aims. We aim to characterize the U-band variability of young brown dwarfs in the Taurus Molecular Cloud and discuss its origin.
Methods. We used the XMM-Newton Extended Survey of the Taurus Molecular Cloud, where a sample of 11 young bona fide brown
dwarfs (spectral type later than M6) were observed simultaneously in X-rays with XMM-Newton and in the U-band with the
XMM-Newton Optical/UV Monitor (OM).
Results. We obtained upper limits to the U-band emission of 10 brown dwarfs (U19.620.6 mag), whereas
2MASS J04141188+2811535 was detected in the U-band. Remarkably, the magnitude of this brown dwarf increased regu-
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