Herschel Orion Protostar Survey


Understanding protostellar evolution is a necessary step toward characterizing the factors which ultimately determine the properties of emerging stars and their planetary systems. The Orion molecular cloud complex is the most active region of star formation within 500 pc of the Sun, with over 400 protostars identified by Spitzer in a diverse range of environments.  The Herschel Orion Protostar Survey is a Key Program composed of  far-infrared imaging and spectroscopy.  We have obtained deep PACS 70 and 160 micron imaging for 283 protostars ranging in luminosity from 0.1 to 1000 Lsun and spanning the Class 0, Class I and flat spectrum evolutionary phases. The high sensitivity and angular resolution of the PACS camera enables us to measure bolometric luminosities in crowded fields, removing potentially significant contributions from external heating. In concert with existing near-IR and Spitzer mid-IR images and spectra and high resolution APEX SABOCA and LABOCA submillimeter cintinuum observations, the deep PACS imaging are being use by our team to determine the fundamental properties of the protostellar envelopes and disks (properties such as envelope structure, density and angular momentum, disk luminosity). PACS spectroscopy of 37 protostars are being used to measure water vapor, OH and O lines arising in the envelope, in the accretion shock onto the central protostellar disk, and in outflows. These data will provide an unparalleled view of the flow of material from the envelope onto the disk, through the disk to the star, and away from the star in outflows. The Orion molecular cloud complex contains an exceptionally wide range of parental gas conditions (i.e. initial conditions) and environments (from dense clusters to relatively isolated protostars). By comparing the properties of protostars in different regions of Orion clouds; we will assess the roles of initial conditions, environment and feedback from outflows in guiding protostellar evolution. These observations will produce a unique legacy dataset for guiding and testing theories of protostellar evolution.