TITLE: Adaptive Optics Observations of Young Stars in Orion OB1

AUTHOR: Cesar Briceno
Cerro Tololo Interamerican Observatory
Casilla 603, La Serena, Chile

ABSTRACT:
I present preliminary results from a multiplicity study of pre-main sequence 
stars in the Orion OB1 Association, including early type members of the 25 
Orionis cluster like the HAeBe star V346 Ori. We have carried out 
observations of ~50 young stars using the NACO instrument on VLT and the SOAR 
Adaptive Optics Module (SAM).
Our goal is to determine population-wide multiplicity properties of low mass 
young stars at ages 4-10 Myr, a critical time when disks are dissipating and 
planetary systems have largely completed their formation process.
The multiplicity fraction for single and binary systems, in disked/non-disked 
stars of differing ages, can provide key constraints for understanding 
circumstellar disk survival and evolution.