The Formation and Feedback of Massive Stellar Clusters

Dr. Eric Feigelson (Pennsylvania State University) and his collaborators will carry out a multi-faceted investigation into the astrophysics of massive star-forming regions (MSFRs). This work is founded on the recent recognition that sensitive high-resolution X-ray images of rich young stellar clusters and their associated gaseous environments give critical information unavailable at longer wavelengths. The Chandra X-ray Observatory provides large, well-defined, and nearly disk-unbiased samples of pre-main sequence and massive cluster members with negligible contamination from older field stars. These X-ray sources have subarcsecond positions, are readily associated with stars from infrared (IR) surveys, and can be identified even through heavy absorption. When these stellar sources are removed, the X-ray images reveal faint diffuse emission produced by shocked O star winds suffusing HII regions on parsec scales. Combining the X-ray-selected sample with IR-excess sources, established from near- and mid-IR surveys, will result in the best stellar census available with thousands of low-mass, hundreds of intermediate-mass, and dozens of OB stellar members in 20 MSFRs with ages less than or equal to 8 million years, lying within 4 kiloparsecs of the Sun. Using this uniform, detailed database, the team will then pursue astrophysical investigations into the structure and origins of rich stellar clusters, and their feedback onto their natal clouds. The work is conducted in collaboration with expert, international groups located at the University of Exeter, McMaster University, and the University of Leeds.

In addition to providing detailed understanding of the 20 targeted MSFRs, this work should significantly deepen our general astrophysical understanding of star formation in the Galaxy. These results will strengthen our ability to predict the evolution of protoplanetary disks in hostile environments near OB stars. This work also represents an early synergism between high-energy X-ray astronomy and ground-based optical/IR astronomy for understanding the complex processes of star formation and Galactic ecology. Members of this team will also conduct a program of outreach to an underserved population of rural Americans who have little access to modern science and technology. During the award period, they will participate in a new program of in-service workshops for both rural and urban secondary school science teachers.