Disk and Envelope Streamers of the GGD27-MM1 Massive Protostar

TL;DR

This study uses high-resolution ALMA observations to analyze the structure and dynamics of the disk, envelope, and potential accretion streamers around the massive protostar GGD27-MM1, revealing complex molecular and dust features.

Contribution

It provides a detailed characterization of the disk, envelope, and streamers in GGD27-MM1, including temperature, density maps, and a theoretical model of the accretion structures, which advances understanding of high-mass star formation.

Findings

Identification of disk extending up to 190 au

Detection of possible accretion streamers in molecular tracers

Evidence of an inner zone devoid of molecular content

Abstract

We present new Atacama Large (sub)Millimeter Array 0.98 mm observations of the continuum emission and several molecular lines toward the high-mass protostellar system GGD27-MM1, driving the HH 80-81 radio-jet. The detailed analysis of the continuum and the CH$_3$CN molecular emission allows us to separate the contributions from the dust content of the disk (extending up to 190 au), the molecular content of the disk (extending from 140 to 360 au), and the content of the envelope, revealing the presence of several possible accretion streamers (also seen in other molecular tracers, such as CH$_3$OH). We analyze the physical properties of the system, producing temperature and column density maps, and radial profiles for the disk and the envelope. We qualitatively reproduce the trajectories and line-of-sight velocities of the possible streamers using a theoretical model approach. An ad-hoc model of a flared disk comprising a hot dust disk embedded in cold gas fits the H$_2$S emission, which revealed the molecular disk as crescent-shape with a prominent central absorption. Another fit to the central absorption spectrum suggests that the absorption is probably caused by different external cold layers from the envelope or the accretion streamers. Finally, the analysis of the rotation pattern of the different molecular transitions in the molecular disk, suggests that there is an inner zone devoid of molecular content.