Work

Trigonometric Parallaxes of Maser Sources toward the Far Side of the Milky Way

Year: 2026

Type: article

Abstract: We present trigonometric parallaxes and proper motions for eight maser sources associated with high-mass star-forming regions. Four 22 GHz H 2 O masers and four 6.7 GHz CH 3 OH masers were observed over eight epochs between 2024 and 2025. Combining parallax, proper-motion, and radial-velocity information, we determine distances and spiral-arm assignments for these sources. The newly measured far-side masers extend the known distributions of the Sagittarius and Perseus arms toward Galactic longitudes as small as ℓ ∼ 10 ∘ . Their locations and kinematics agree well with recently updated spiral-arm models based on maser astrometry. In particular, the new measurements show that the far-side Sagittarius and Perseus arms tend to converge toward a common spiral feature in the inner Galaxy. This configuration is consistent with the bifurcation scenario proposed for the Milky Way spiral structure, although an unresolved interarm structure provides an alternative interpretation that cannot yet be excluded.

Source: The Astrophysical Journal Supplement Series

DOI: 10.3847/1538-4365/aead92

Authors: Z. H. Lin, Y. Xu, M. Reid, J. J. Li, S. B. Bian

Institutions: Purple Mountain Observatory, University of Science and Technology of China, Xinjiang Astronomical Observatory, Center for Astrophysics Harvard & Smithsonian

Language: English

Topic: Stellar, planetary, and galactic studies

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $4,499

Funder: National Natural Science Foundation of China