Title:Dynamics of low-mass star clusters: the detection of stellar haloes

Abstract:
PMS clusters are excellent laboratories for studying dynamical interactions. Examples are the eta Cha and 
eps Cha clusters; nearby, sparse, compact, 5-10 Myr-old systems deficient by a factor of 2 in low-mass 
stars and brown dwarfs. Sensitive searches have completed the core population and found no members in 
the immediate field, to 2-3 times the core radius. The latest photometric and proper motion surveys have 
sufficient precision to detect members distant from the core. Observational constraints are severe; 
candidate members must be photometrical consistent with core members, have Li and other indicators of 
consistent with the cluster age, and have space velocities consistent with ejection early in the cluster''s life. 
In the case of eta Cha, candidates members have now been detected up to 5.5 deg spatial separation from 
the cluster core.