THE DISCOVERY OF THE YOUNGEST MOLECULAR OUTFLOW ASSOCIATED WITH AN INTERMEDIATE-MASS PROTOSTELLAR CORE, MMS-6/OMC-3

We present subarcsecond resolution HCN (4-3) and CO (3-2) observations made with the Submillimeter Array, toward an extremely young intermediate-mass protostellar core, MMS 6-main, located in the Orion Molecular Cloud 3 region (OMC-3). We have successfully imaged a compact molecular outflow lobe (≈1000 AU) associated with MMS 6-main, which is also the smallest molecular outflow ever found in the intermediate-mass protostellar cores. The dynamical timescale of this outflow is estimated to be ≤100 yr. The line width dramatically increases downstream at the end of the molecular outflow (Δv ∼ 25 km s–1) and clearly shows the bow-shock-type velocity structure. The estimated outflow mass (≈10–4 M☉) and outflow size are approximately two to four orders and one to three orders of magnitude smaller, respectively, while the outflow force (≈10–4 M☉ km s–1 yr–1) is similar, compared to the other molecular outflows studied in OMC-2/3. These results show that MMS 6-main is a protostellar core at the earliest evolutionary stage, most likely shortly after the second core formation.