Cool Stars 14 - Submitted Abstract # 150
This version created on 05 October 2006

Simultaneous X-ray, radio, near-infrared, and optical monitoring of
Young Stellar Objects in the Coronet cluster


Jan Forbrich, MPIfR Bonn (Germany)
Thomas Preibisch, MPIfR Bonn (Germany)
Karl M. Menten, MPIfR Bonn (Germany)
R. Neuhaeuser, AIU Jena (Germany)
F. M. Walter, SUNY Stony Brook (USA)
M. Tamura, NAOJ Tokyo (Japan)
N. Matsunaga, University of Tokyo (Japan)
N. Kusakabe, Graduate University for Advanced Studies, Tokyo (Japan)
Y. Nakajima, NAOJ Tokyo (Japan)
A. Brandeker, University of Toronto (Canada)
S. Fornasier, Universita di Padova (Italy)
B. Posselt, MPE Garching (Germany)
K. Tachihara, Kobe University (Japan)
C. Broeg, AIU Jena (Germany)

Multi-wavelength monitoring can provide important information about
physical processes in young stellar objects such as the relation
between accretion processes and X-ray emission.  While coronal
processes should mainly cause variations in the X-ray and radio bands,
accretion processes may be traced by time-correlated variability in
the X-ray and optical/infrared bands.  We present the first
simultaneous X-ray, radio, near-infrared, and optical multi-wavelength
monitoring campaign succeeding in detecting X-ray to radio variability
in extremely young objects like class I and class 0  protostars.  Our
target is the compact Coronet cluster in the Corona Australis
star-forming region, harbouring at least one class 0  protostar,
several class I objects, numerous T Tauri stars, and a few Herbig AeBe
stars.  A core sample of seven objects was detected simultaneously in
the X-ray, radio, and optical/infrared bands.  While most of these
sources exhibit clear variability in the X-ray regime and several
display also optical/infrared variability, none of them shows
significant radio variability on the timescales probed.  We also do
not find any case of clearly time-correlated optical/infrared and
X-ray variability.  This suggests that there is no direct link between
the X-ray and optical/infrared emission, supporting the notion that
accretion is not an important source for the X-ray emission of these
YSOs.  Combining our Chandra data with previous observations results
in one of the most sensitive X-ray observations yet of a star-forming
region allowing a virtually complete census of YSOs in the Coronet
region.

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