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K. Jorgensen (Lewis & Clark College, National Radio Astronomy Observatory Summer REU Student), Y. Shirley (National Radio Observatory Jansky Fellow, University of Arizona)
A pre-protostellar core is the earliest detectable stage of star formation and are undoubtedly the least understood formation phase of low-mass stars. In order to better understand the pre-protostellar phase, parameters such as the central densities of the cores, how embedded the cores are, and the strength of the interstellar radiation field around them are needed. These properties are found by radiative transfer modeling of these systems. This project focused on starless cores observed with the Sub-millimeter Common User Bolometer Array (SCUBA) at the James Clerk Maxwell Telescope. Nearly every pre-protostellar core with a distance < 400 pc that has been observed with SCUBA in jiggle mapping mode at 850 and 450 microns was obtained from the CADC archive and reduced. From this sample, 32 cores fit the criteria to undergo radiative transfer modeling. Using pressure-bounded isothermal spheres in hydrostatic equilibrium as our physical model we obtain central density values for each core, finding median central density of log nc = 5.3. We also constrain values for the strength of the interstellar radiation field and Av for 31 of these cores. Many of the cores were found to have central densities too high to be in static equilibrium implying that either the cores observed are in their collapse phase or there is some non-thermal form of support (.e.g, turbulence or magnetic forces). Observations with high resolution spectroscopy are needed to determine the stability of these pre-protostellar cores. We wish to acknowledge the National Radio Astronomy Observatory and the National Science Foundation for funding for this project as well as the NRAO Research Employment for Undergraduates program.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.