Scientific Highlights with the SMA

Spatially Resolving Substructures within the Massive Protostellar Envelope in Orion

Highest angular resolution achieved with the SMA 850 micron continuum observations (0.3 arcsec) has revealed detailed spatial structures within a massive protostellar envelope, MMS 6-main located in the Orion Molecular Cloud 3 region (left panel of the figure). The observing data show the extremely high column density (1.5x10¹⁰ cm^-3) and warm gas (T > 52K) in the central 120 AU. Detailed model comparisons clearly show that the self-luminous source is necessary to explain the observed high flux density (right panel of the figure), suggesting that MMS 6 is one of the first cases of an intermediate-mass protostellar core at an extremely young stage.
In addition to the central component, we have also spatially resolved a number of spiky structures and sub-clumps, distributed over the central 1000 AU (denoted as 1- 7 in the right panel of the figure). The masses of these sub-clumps are estimated to be 0.066-0.073 M_sun, which are on the order of brown dwarf masses. These structures might be originated from fragmentations, spiral arms, or inhomogeneity within the disk-like structures/envelope. (Takahashi, S., Saigo, K., Ho, P. T. P., & Tomida, K., 2012, ApJ, 752, 10 ADS)

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