2022ApJ...925...41D

We present line and continuum observations (resolution ∼0.''3-3.''5) made with the Atacama Large Millimeter/submillimeter Array (ALMA), Submillimeter Array, and Very Large Array of a young O-type protostar W42-MME (mass: 19 ± 4 M _☉). The ALMA 1.35 mm continuum map (resolution ∼1'') shows that W42-MME is embedded in one of the cores (i.e., MM1) located within a thermally supercritical filament-like feature (extent ∼0.15 pc) containing three cores (mass ∼1-4.4 M _☉). Several dense/hot gas tracers are detected toward MM1, suggesting the presence of a hot molecular core with a gas temperature of ∼38-220 K. The ALMA 865 µm continuum map (resolution ∼0.''3) reveals at least five continuum sources/peaks (A-E) within a dusty envelope (extent ∼9000 au) toward MM1, where shocks are traced in the SiO (8-7) emission. Source A associated with W42-MME is seen almost at the center of the dusty envelope and is surrounded by other continuum peaks. The ALMA CO (3-2) and SiO (8-7) line observations show the bipolar outflow extended below 10,000 au, which is driven by source A. The ALMA data hint at the episodic ejections from W42-MME. A disk-like feature (extent ∼2000 au, mass ∼1 M _☉) with velocity gradients is investigated in source A (dynamical mass ∼9 M _☉) using the ALMA H¹³CO⁺ emission, and it is perpendicular to the CO outflow. A small-scale feature (below 3000 au), probably heated by UV radiation from the O-type star, is also investigated toward source A. Overall, W42-MME appears to gain mass from its disk and the dusty envelope.