XMM Imaging of the Cep OB3: Studying Cluster formation within an OB Association

We propose two, 50 ks, XMM observations to search for 510 Myr diskless youngstars in the CepOB3 association at 700 pc. We have recently performed a Spitzerand Chandra study of Cep OB3b and have found this cluster to contain virgul2000stars, making it one of two known, massive (>1000 member) embedded/partiallyembedded clusters within 1 kpc. Cep OB3b has largely dispersed its gas andappears to be a more evolved (35 Myr vs 12 Myr) analog to the other nearbymassive embedded cluster, the the Orion Nebula Cluster. The XMM observationswill map the distribution of 510 Myr stars to understand the relationship ofCep OB3b cluster to previous episodes of star formation in the Cep OB3association. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]