The Rotating Molecular Structures and the Ionized Outflow Associated with IRAS 16547-4247

TL;DR

This study investigates the complex rotating structures, ionized outflows, and multiple sources in the massive star formation region IRAS 16547-4247 using radio and molecular observations, revealing a rotating disk or ring and associated masers.

Contribution

It provides new high-resolution observations of the rotating structures and outflows in IRAS 16547-4247, identifying a rotating ring or disk and linking maser emissions to the outflow and core.

Findings

Evidence of a rotating structure at small scales (~50 AU) from water masers.

Detection of a velocity gradient at large scales (~1000 AU) consistent with a rotating ring or two objects.

Mass estimate of the central source around 30 solar masses.

Abstract

We present VLA 1.3 cm radio continuum and water maser observations as well as SMA SO$_2$ (226.300 GHz) and 1.3 mm dust continuum observations toward the massive star formation region IRAS 16547-4247. We find evidence of multiple sources in the central part of the region. There is evidence of a rotating structure associated with the most massive of these sources, traced at small scales (~50 AU) by the water masers. At large scales (~1000 AU) we find a velocity gradient in the SO2 molecular emission with a barely resolved structure that can be modeled as a rotating ring or two separate objects. The velocity gradients of the masers and of the molecular emission have the same sense and may trace the same structure at different size scales. The position angles of the structures associated with the velocity gradients are roughly perpendicular to the outflow axis observed in radio continuum and several molecular tracers. We estimate the mass of the most massive central source to be around 30 solar masses from the velocity gradient in the water maser emission. The main source of error in this estimate is the radius of the rotating structure. We also find water masers that are associated with the large scale molecular outflow of the system, as well as water masers that are associated with other sources in the region. Our results suggest that the formation of this source, one of the most luminous protostars or protostellar clusters known, is taking place with the presence of ionized jets and disk-like structures.