Kavli Affiliate: Gregory J. Herczeg
| First 5 Authors: Satoko Takahashi, Masahiro N. Machida, Mitsuki Omura, Doug Johnstone, Kazuya Saigo
| Summary:
We present ${sim}0.2$ arcsec ($sim$80 au) resolution observations of the CO
(2-1) and SiO (5-4) lines made with the Atacama large millimeter/submillimeter
array toward an extremely young intermediate-mass protostellar source (t$_{rm
dyn}<$1000 years), 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 $sim$18000 au (red-shifted lobe) and
$sim$35000 au (blue-shifted lobe). We have also detected an extremely compact
($lesssim$1000 au) and collimated SiO protostellar jet within the CO outflow.
The maximum deprojected jet speed is measured to be as high as 93 km s$^{-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 $mu$m light curve obtained with JCMT/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 years.
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