Assigned ID: 857 ----- Attempting Submission 1 (Sat Mar 08 00:28:58 GMT 2008) ----- We propose an archival study of astrometry in the Orion Nebula Cluster, analyzing data from four previous surveys of the ONC core with WFPC2 and ACS/WFC. This program will allow us to measure precise proper motions of individual cluster members, characterizing the intra-cluster velocity distribution and directly studying the dynamical signatures of star formation and early cluster evolution. Our astrometric uncertainties (~1 mas at each epoch) will allow us to calculate individual stellar velocities to unprecedented precision (~0.2 mas/yr; 0.4 km/s), and since these velocities are parallel to the projected spatial distribution of cluster members, we can directly relate these stellar velocities to spatial substructure within the cluster. We will also conduct a wider-field survey exploiting observations of the cluster halo from the two ACS/WFC surveys, which covered ten times the area (400 square arcminutes) but with a shorter time baseline. Finally, both components of our survey will allow us to probe other topics in small-scale star formation physics by searching for high-velocity stars ejected from decaying multiple systems, expanding our knowledge of multiplicity in dense environments, and testing the membership of candidate cluster members based on kinematic membership tests.

STAR FORMATION 12 75000 false 0.0 0.0 false false false false false SUPPORTED