Cool Stars 14 - Submitted Abstract # 224
This version created on 05 October 2006

HST ACS Imaging of the Fluoresced Ultraviolet Molecular Hydrogen
Emission Around T Tauri


Alexander Brown, University of Colorado
Frederick Walter, SUNY - Stony Brook
Thomas Ayres, University of Colorado 
Gregory Herczeg, California Institute of Technology
Joanna Brown, California Institute of Technology
Jack Lissauer, NASA Ames Research Center

The interactions between a newly-formed star and its circumstellar
disk and bipolar outflows play a central role in the process of star
formation.  These interactions control how disks evolve and dissipate,
and thereby control the process of planetary system formation.  We
have imaged the fluorescent UV molecular hydrogen emission from
shock-excited gas around the pre-main-sequence binary T Tauri N and S
using the HST ACS camera.  Our SBC (solar blind channel) MAMA images
show the detailed spatial properties of the molecular H emitting
regions down to scales of 5-10  AU.  The circumstellar disk of T Tau S
is seen clearly in absorption against the glowing molecular gas.  In
contrast, T Tau N is clearly located behind the majority of the
molecular H and its disk is not seen in silhouette.  STIS spectra
showed molecular H emission lines that suggested the influence of H
Lyman alpha radiation originating from sources with different line
profiles and our images explain this phenomenon.  The gas near T Tau N
is excited by that star but the emission knot situated 1.3 arcsec
south is excited by the hidden T Tau S.  This southern knot originates
from a standing shock in the T Tau S outflow.  We present our
molecular hydrogen images and discuss the detailed interpretation of
the observed structures and the implied structure of the T Tau S disk.

----------------------------------