Initial Results from the Spitzer Young Stellar Cluster Survey

We report initial results from IRAC observations of four young stellarclusters. These regions are part of a larger Spitzer survey of 31 young stellargroups and clusters within 1 kpc of the Sun. In each of the four clusters,there are between 39 and 85 objects with colors inconsistent with reddenedstellar photospheres. We identify these objects as young stars with significantemission from circumstellar dust. Applying an analysis developed in a companionpaper (Allen et al. 2004), we classify these objects as either pre-mainsequence stars with disks (class II) or protostellar objects (class I). Theseshow that the sites of recent star formation are distributed over multi-parsecsize scales. In two clusters, Cepheus C and S140, we find protostars embeddedin filamentary dark clouds seen against diffuse emission in the IRAC bands.Comment: Accepted to the Spitzer special issue of the Astrophysical Journal Supplemen