An Extremely Young Protostellar Core, MMS 1/OMC-3: Episodic Mass Ejection History Traced by the Micro SiO Jet

• Published in: The Astrophysical journal Vol. 964; no. 1; pp. 48 - 61
• Main Authors: Takahashi, Satoko, Machida, Masahiro N., Omura, Mitsuki, Johnstone, Doug, Saigo, Kazuya, Harada, Naoto, Tomisaka, Kohji, Ho, Paul T. P., Zapata, Luis A., Mairs, Steve, Herczeg, Gregory J., Taniguchi, Kotomi, Liu, Yuhua, Sato, Asako
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.03.2024; IOP Publishing
• Subjects: Ejection; Light curve; Molecular clouds; Numerical simulations; Outflow; Protostars; Radio telescopes; Shocks; Star formation; Stellar jets; Stellar winds
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad2268

Abstract We present ∼0.″2 (∼80 au) resolution observations of the CO(2–1) and SiO(5–4) lines made with the Atacama large millimeter/submillimeter array toward an extremely young intermediate-mass protostellar source ( t dyn < 1000 yr), MMS 1 located in the Orion Molecular Cloud-3 region. We have successfully imaged a very compact CO molecular outflow associated with MMS 1, having deprojected lobe sizes of ∼1800 au (redshifted lobe) and ∼2800 au (blueshifted lobe). We have also detected an extremely compact (≲1000 au) and collimated SiO protostellar jet within the CO outflow. The maximum deprojected jet speed is measured to be as high as 93 km s −1 . The SiO jet wiggles and displays a chain of knots. Our detection of the molecular outflow and jet is the first direct evidence that MMS 1 already hosts a protostar. The position–velocity diagram obtained from the SiO emission shows two distinct structures: (i) bow shocks associated with the tips of the outflow, and (ii) a collimated jet, showing the jet velocities linearly increasing with the distance from the driving source. Comparisons between the observations and numerical simulations quantitatively share similarities such as multiple-mass ejection events within the jet and Hubble-like flow associated with each mass ejection event. Finally, while there is a weak flux decline seen in the 850 μ m light curve obtained with the James Clerk Maxwell Telescope/SCUBA 2 toward MMS 1, no dramatic flux change events are detected. This suggests that there has not been a clear burst event within the last 8 yr.