The nature of the methanol maser ring G23.657-00.127

TL;DR

This study uses multi-epoch VLBA observations of a methanol maser ring to measure its distance and motion, providing insights into high-mass star formation and maser emission origins.

Contribution

It presents the first precise parallax and proper motion measurements of the methanol maser ring G23.657-00.127, enhancing understanding of its physical properties and kinematics.

Findings

Parallax of 0.313 mas, distance of 3.19 kpc.

Source exhibits large peculiar motion (~35 km/s).

Consistent circular velocity with the local standard of rest.

Abstract

Methanol masers are associated with young high-mass stars and are an important tool for investigating the process of massive star formation. The recently discovered methanol maser ring in G23.657-00.127 provides an excellent ``laboratory'' for a detailed study of the nature and physical origin of methanol maser emission, as well as parallax and proper motion measurements. Multi-epoch observations of the 12.2 GHz methanol maser line from the ring were conducted using the Very Long Baseline Array. Interferometric observations with milliarcsecond resolution enabled us to track single maser spots in great detail over a period of 2 years. We have determined the trigonometric parallax of G23.657-00.127 to be 0.313+/-0.039 mas, giving a distance of 3.19{+0.46}{-0.35} kpc. The proper motion of the source indicates that it is moving with the same circular velocity as the LSR, but it shows a large peculiar motion of about 35 km/s toward the Galactic center.