Modeling the accretion disk around the high-mass protostar GGD 27-MM1

TL;DR

This study models the accretion disk around the high-mass protostar GGD 27-MM1 using high-resolution ALMA data, revealing a compact, massive, and hot disk with implications for star formation theories.

Contribution

We present detailed radiative transfer models of a high-mass protostar's accretion disk, providing new physical parameters and insights into its structure and stability.

Findings

The disk is compact (~170 au) and massive (~5 solar masses).

The star-disk system's total mass is estimated between 21 and 30 solar masses.

The disk is hotter and more massive than low-mass star disks, yet remains stable.

Abstract

Recent high-angular resolution (40 mas) ALMA observations at 1.14 mm resolve a compact (R~200 au) flattened dust structure perpendicular to the HH 80-81 jet emanating from the GGD 27-MM1 high-mass protostar, making it a robust candidate for a true accretion disk. The jet/disk system (HH 80-81 / GGD 27-MM1) resemble those found in association with low- and intermediate-mass protostars. We present radiative transfer models that fit the 1.14 mm ALMA dust image of this disk which allow us to obtain its physical parameters and predict its density and temperature structure. Our results indicate that this accretion disk is compact (Rdisk~170 au) and massive (5Msun), about 20% of the stellar mass of 20 Msun. We estimate the total dynamical mass of the star-disk system from the molecular line emission finding a range between 21 and 30 Msun, which is consistent with our model. We fit the density and temperature structures found by our model with power law functions. These results suggest that accretion disks around massive stars are more massive and hotter than their low-mass siblings, but they still are quite stable. We also compare the temperature distribution in the GGD 27-MM1 disk with that found in low- and intermediate-mass stars and discuss possible implications on the water snow line. We have also carried about a study of the distance based on Gaia DR2 data and the population of young stellar objects (YSOs) in this region, and from the extinction maps. We conclude that the source distance is in within 1.2 and 1.4 kpc, closer than what was derived in previous studies (1.7 kpc).