Cool Stars 14 - Submitted Abstract # 16
This version created on 05 October 2006

Short-Term Emission Line Variability in the Accreting Young Brown
Dwarf 2MASS 1207-3932


Beate Stelzer, Osservatorio Astronomico di Palermo
Alexander Scholz, University of Toronto 
Ray Jayawardhana, University of Toronto

The brown dwarf 2MASS 1207-3932, a member of the TW Hya association,
is known to display strong and variable Hydrogen Balmer line emission.
Its broad H_alpha profiles indicate that a substantial fraction of the
emission must be attributed to disk accretion rather than to magnetic
activity.  Variability of the strength of these lines should therefore
trace changes in the accretion rate, and a study of the line profiles
gives access to the disk-star geometry.  In particular, the shape of
the profiles has been shown previously to vary on the rotational
timescale (~1 day for 2M1207).  In order to investigate short-term
emission line variations related to accretion, activity and rotation,
we have obtained a series of high-resolution optical spectra for
2M1207 during two consecutive observing nights at the VLT with UVES.
These data allow us to examine the emission line variability with a
resolution of ~20  min, over a wide spectral range (~3750-5000  AA and
~5900-9500  AA).

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