Probes of Protostellar Structure with Spitzer
First Author:
John Tobin
Email: jjtobin AT umich.edu
University of Michigan
500 Church St., 830 Dennison Building
Ann Arbor, MI 48109, USA
Coauthors:
Hartmann, Lee, University of Michigan
Looney, Leslie, University of Illinois
Chiang, Hsin-Fang, University of Illinois
Abstract
We present initial results from a Spitzer archival study of protostellar structure. We have selected 30 protostars within 450 pc which exhibit resolved scattered light cavities in IRAC observations. Protostellar structure provides the initial conditions of disk formation. Specifically, the compositon of the dusty envelope and its infall rate influence the resultant properties of the circumstellar disk. We employ a Monte Carlo radiative transfer code to model the envelope structure and SED as viewed in scattered light cavities and thermal emission from NIR to millimeter wavelengths. In addition to the constraints given by radiative transfer modeling, we directly probe the envelope structure observed in absorption against background ISM emission at 8.0 microns. Some envelopes exhibit an approximately spherical structure, while most have complicated morphologies including flattened geometries. We have used these data to construct optical depth maps of these envelopes and calculated their masses based on tabulated opacities and distances.
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