Dense gas and exciting sources of the molecular outflow in the AFGL 437 star-forming region

TL;DR

This study uses high-resolution VLA observations of ammonia and other data to investigate the molecular outflows in AFGL 437, revealing multiple bipolar outflows that explain the previously observed poorly collimated CO outflow.

Contribution

It provides new high-resolution ammonia observations and suggests the presence of multiple bipolar outflows in AFGL 437, clarifying the outflow morphology.

Findings

Ammonia emission is concentrated in three main clumps near the infrared cluster.

A jet-like structure is detected in the continuum emission at 2 cm.

The CO outflow is likely a superposition of multiple individual outflows.

Abstract

We present Very Large Array (VLA) high resolution observations of the NH3(1,1) and NH3(2,2) molecular transitions towards the high mass star forming region AFGL 437. Our aim was to investigate if the poorly collimated CO molecular outflow previously detected in the region is the result of a projection effect, with no intrinsic bipolarity, as suggested by Gomez et al. We complemented our observations with radio continuum archived data from the VLA at 2 and 3.6 cm, and with unpublished public data at 450 {\mu}m taken with Submillimetre Common-User Bolometer Array at the James Clerk Maxwell Telescope. Ammonia emission was found mainly in three clumps located at the south and east of the position of the compact infrared cluster of AFGL 437, where the CO outflow seemed to have its origin. One of the NH3(1,1) clumps coincides with the maximum of NH3(2,2) and with a local peak of emission at 450 {\mu}m. A near infrared source (s11) is also found at that position. Our continuum map at 2 cm shows extended elongated emission associated with the infrared source AFGL 437W. This elongated morphology and its spectral index between 3.6 and 2 cm (\simeq 0.4) suggest the presence of a jet in AFGL 437W. We suggest that several molecular bipolar outflows may exist in the region. The observed CO outflow would be the superposition of those individual outflows, which would explain its low degree of collimation observed at larger scales.