Trigonometric Parallaxes of Maser Sources toward the Far Side of the Milky Way
5 affiliations
- 1Purple Mountain Observatory
- 2State Key Laboratory of Radio Astronomy and Technology
- 3University of Science and Technology of China
- 4Xinjiang Astronomical Observatory
- 5Center for Astrophysics ∣ Harvard & Smithsonian
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.
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BibTeX
@article{lin2026trigonometric,
title = {{Trigonometric Parallaxes of Maser Sources toward the Far Side of the Milky Way}},
author = {Z. H. Lin and Y. Xu and M. Reid and J. J. Li and S. B. Bian},
journal = {The Astrophysical Journal Supplement Series},
year = {2026},
month = nov,
doi = {10.3847/1538-4365/aead92},
url = {https://iopscience.iop.org/article/10.3847/1538-4365/aead92},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Trigonometric Parallaxes of Maser Sources toward the Far Side of the Milky Way
AU - Z. H. Lin
AU - Y. Xu
AU - M. Reid
AU - J. J. Li
AU - S. B. Bian
PY - 2026
DA - 2026/11/03
JO - The Astrophysical Journal Supplement Series
DO - 10.3847/1538-4365/aead92
UR - https://iopscience.iop.org/article/10.3847/1538-4365/aead92
AB - 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.
SN - 0067-0049
SN - 1538-4365
ER -