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C. H. Young, Y.L. Shirley, N.J. Evans II (University of Texas--Austin), J.M.C. Rawlings (University College London)
The current state of low-mass star formation holds numerous theories, each of which predicts the evolving nature of the protostar and surrounding envelope. In particular, these theories predict the distribution of matter, often defined as a power law (n\propto r-p), and, further, describe how this distribution changes with time (i.e. n(\vec{r},t)).
Dust emission, at submillimeter wavelengths, is optically thin and, hence, traces the entire surrounding envelope. Therefore, one can determine, directly, the distribution of material in the cloud by observing and analyzing the intensity profile.
We present the results from an observing campaign aimed at understanding the evolution of these protostellar environments. Our sample consists of 39 sources that span the evolutionary sequence of low-mass objects from Class -1 (preprotostellar) to Class I (pre-T Tauri) cores. We have observed these cores with SCUBA on the JCMT at submillimeter wavelengths.
In addition, we report the results for the modeling of the submillimeter emission from these cores. By computing the radiative transfer of the dust emission and simulating the observations, we have modeled the radial intensity profiles at 450 and 850 microns and, simultaneously, the SED for 16 of the observed cores (3 PPC, 7 Class 0, and 6 Class I). Four different density distributions were tested: Bonnor-Ebert, Plummer, power-law, and Shu inside-out collapse, and we discuss the best-fit models for all 16 sources. Particularly, we discuss, in detail, representative sources from each of the three evolutionary stages and note how the envelope mass has evolved in conjunction with the central protostar. Further, even though this is a culmination of a major study in the evolution of low-mass stars, we conclude with future plans for observations and modeling of these objects.