Massive young stellar object W42-MME: the discovery of an infrared jet using VLT/NACO near-infrared images

Abstract

We report on the discovery of an infrared jet from a deeply embedded infrared counterpart of the 6.7 GHz methanol maser emission (MME) in W42 (i.e., W42-MME). We show that W42-MME drives a parsec-scale H2 outflow, with the detection of a bow shock feature at ~0.52 pc to the north. The inner ~0.4 pc part of the H2 outflow has a position angle of ~18° and the position angle of ~40° is found farther away on either side of the outflow from W42-MME. W42-MME is detected at wavelengths longer than 2.2 μm and is a massive young stellar object with an estimated stellar mass of 19 ± 4 Mo. We map the inner circumstellar environment of W42-MME using Very Large Telescope (VLT)/NACO adaptive optics Ks and L' observations at resolutions of ~0"2 and ~0"1, respectively. We discover a collimated jet in the inner 4500 AU using the L' band, which contains prominent Brα line emission. The jet is located inside an envelope/cavity (extent ~10,640 AU) that is tapered at both ends and is oriented along the north–south direction. Such observed morphology of the outflow cavity around the massive star is scarcely known and is very crucial for understanding the jet-outflow formation process in massive star formation. Along the flow axis, which is parallel to the previously known magnetic field, two blobs are found in both the NACO images at distances of ~11800 AU, located symmetrically from W42-MME. The observed W42-MME jet-outflow configuration can be used to constrain the jet launching and jet collimation models in massive star formation.