It is not always possible to separate individual young stars in clustered regions with single dish bolometer observations. The SMA has been crucial in identifying and characterizing very young cluster members in nearby regions, as well as identifying small pre-stellar cores (Lee et al. 2006, 2007; Teixeira et al. 2007). This capability allows for a more complete stellar census when combined with other data, in particular infrared observations. Such observations allow the star formation history and efficiency to be accurately determined, information that is extremely important for testing star formation theories of cluster formation, the dominant star formation mode.

IRAS 16293-2422 is a relatively isolated system within the Ophiuchus molecular cloud (160 pc). It has been known for many years to be a binary of separation 5" (800 pc) and to exhibit numerous bright molecular lines. These properties make it an ideal source for targeted SMA studies. Results include the separation of one of the pair into a close binary system of separation 0.5" (Chandler et al. 2005); the study of infall motions around each member of the wide binary (Takakawa et al. 2007); the identification of the driving source of a large scale outflow (Yeh et al. 2007); and the identification of the very different chemical histories associated with each source (Kuan et al. 2004; Bisschop et al. 2008). Recent eSMA observations reveal that toward one member most molecular lines are seen in absorption on very small scales (Frieswijk et al., in prep; Figure 4).

Click here for larger view

Figure 4: eSMA observations of the multiple system IRAS 16293. The figure shows the full 2 GHz wide spectrum near 338 GHz toward the main components, labeled A (bottom) and B (top). The 338 GHz spectral band toward A is completely filled with lines, mostly CH3OH (the closely spaced line forest seen in the lower panel). At the continuum peak of B, many narrow lines are seen only in absorption (upper panel), a result only seen with the resolution provided by the eSMA (about 0.3") (Frieswijk et al. in prep.).

References:

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T. L. Bourke, A. Crapsi, P. C. Myers, N. J.II Evans, D. J. Wilner, T. L. Huard, J. K. Jørgensen, C. H. Young, Discovery of a Low Mass Bipolar Molecular Outflow from L1014- IRS with the Submillimeter Array, 2005, ApJ, 633, L129

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C.-F. Lee, P. T.P. Ho, A. Palau, N. Hirano, T. L. Bourke, H. Shang, Q. Zhang, Submillimeter arcsecond-resolution mapping of the highly collimated protostellar jet HH 211, 2007, ApJ, 670, 1188

C.-F. Lee, Y.-Y. Mao, B. Reipurth, Infall and rotation motions in the HH 111 protostellar system: A flattened envelope in transition to a disk?, 2009, ApJ, 694, 1395

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SMA Research: Low Mass Star Formation

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