ALMA Fragmented Source Catalog in Orion (FraSCO). I. Outflow Interaction within an Embedded Cluster in OMC-2/FIR 3, FIR 4, and FIR 5

Abstract

We present a high-angular resolution (∼1″) and wide-field ( $2\buildrel{\,\prime}\over{.} 9\times 1\buildrel{\,\prime}\over{.} 9$ ) image of the 1.3 mm continuum, CO( J = 2–1) and SiO( J = 5–4) line emissions toward an embedded protocluster, FIR 3, FIR 4, and FIR 5, in the Orion Molecular Cloud 2 obtained from the Atacama Large Millimeter/submillimeter Array. We identify 51 continuum sources, 36 of which are newly identified in this study. Their dust masses, projected sizes, and H _2 gas number densities are estimated to be 3.8 × 10 ^−5 –1.1 × 10 ^−2 M _⊙ , 290–2000 au, and 6.4 × 10 ^6 –3.3 × 10 ^8 cm ^−3 , respectively. The results of a Jeans analysis show that ∼80% of the protostellar sources and ∼15% of the prestellar sources are gravitationally bound. We identify 12 molecular outflows traced in the CO( J = 2–1) emission, six of which are newly detected. We spatially resolve shocked gas structures traced by the SiO( J = 5–4) emission in this region for the first time. We identify shocked gas originating from outflows and other shocked regions. These results provide direct evidence of an interaction between dust condensation, FIR 4, and an energetic outflow driven by HOPS-370 located within FIR 3. A comparison of the outflow dynamical timescales, fragmentation timescales, and protostellar ages shows that the previously proposed triggered star formation scenario in FIR 4 is not strongly supported. We also discuss the spatial distribution of filaments identified in our continuum image by comparing it with a previously identified hub-fiber system in the N _2 H ^+ line.

Keywords

• Protoclusters
• Protostars
• Giant molecular clouds
• Millimeter astronomy