A massive Keplerian protostellar disk with flyby-induced spirals in the Central Molecular Zone

TL;DR

This paper reports the discovery of a massive, stable Keplerian disk around a 32-solar-mass protostar with flyby-induced spirals, suggesting similar formation processes for massive and low-mass stars.

Contribution

It provides the first observational evidence of a massive protostellar disk with flyby-induced spirals, linking disk evolution in high-mass star formation to low-mass star processes.

Findings

Discovery of a gravitationally stable, massive Keplerian disk with spirals.

Identification of a likely flyby perturber causing the spirals.

Massive star formation via disk-mediated accretion influenced by external perturbations.

Abstract

Accretion disks are an essential component in the paradigm of the formation of low-mass stars. Recent observations further identify disks surrounding low-mass pre-main-sequence stars perturbed by flybys. Whether disks around more massive stars evolve in a similar manner becomes an urgent question. We report the discovery of a Keplerian disk of a few solar masses surrounding a 32 solar-mass protostar in the Sagittarius C cloud around the Galactic Center. The disk is gravitationally stable with two embedded spirals. A combined analysis of analytical solutions and numerical simulations demonstrates that the most likely scenario to form the spirals is through external perturbations induced by a close flyby, and one such perturber with the expected parameters is identified. The massive, early O-type star embedded in this disk forms in a similar manner with respect to low-mass stars, in the sense of not only disk-mediated accretion, but also flyby-impacted disk evolution.