Will Fischer Colloquium


Protostellar Evolution in the Orion Molecular Clouds

William Fischer

Support Scientist

Space Telescope Science Institute

In the protostellar phase of low-mass star formation, the central star is embedded in a dense, infalling envelope. This phase lasts about 500,000 yr and is when most of the star's main-sequence mass is assembled. Our understanding of the details of this process has improved in recent years with sensitive mid- and far-infrared surveys of entire star-forming regions. I will present findings based on the Herschel Orion Protostar Survey, which observed over 300 protostars in Orion, the largest available sample in the nearest 500 pc. I find that the luminosities of protostars peak early in their evolution and fall rapidly over time, which can be explained with exponentially declining envelope masses. The smooth decline is punctuated by brief episodes of dramatically enhanced accretion that together are responsible for 25-50% of the ultimate stellar mass.