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次毫米波陣列計畫(SMA)

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The Discovery of the Youngest Molecular Outflow Associated with an Intermediate-mass Protostellar Core in Orion

圖片來源: Takahashi S. and Ho P.

The discovered outflow lobe size (~1000 AU; left panel of the figure) is the smallest molecular outflow ever found in the intermediate-mass protostellar cores. The line width dramatically increases downstream at the end of the molecular outflow (right panel of Figure) and clearly shows the bow-shock-type velocity structure.

ASIAA researchers S. Takahashi and P. Ho discovered an extremely young intermediate-mass protostellar core, MMS 6-main, located in the Orion Molecular Cloud 3 region (OMC-3) with the SMA sub arcsecond resolution HCN (4-3) and CO (3-2) observations. The discovered outflow lobe size (~1000 AU; left panel of the figure) is the smallest molecular outflow ever found in the intermediate-mass protostellar cores. A dynamical timescale of this outflow is estimated to be less than 100 yr. The line width dramatically increases downstream at the end of the molecular outflow (right panel of Figure) and clearly shows the bow-shock-type velocity structure. The estimated outflow mass and size are approximately two to four orders and one to three orders of magnitude smaller, respectively, while the outflow momentum rate is similar, compared to the other molecular outflows studied in OMC-2/3. These results imply that MMS 6-main is a protostellar core at the earliest evolutionary stage, most likely shortly after the protostar formation. (ApJ:745(1), L10, Jan 20, 2012)