Trigonometric Parallaxes of Star Forming Regions in the Perseus Spiral Arm

TL;DR

This study measures precise distances and motions of star-forming regions in the Perseus arm, revealing its structure and dynamics within the Milky Way.

Contribution

It provides new trigonometric parallax measurements and refines the Perseus arm's pitch angle and kinematic properties.

Findings

Perseus arm pitch angle estimated at 9.9 degrees

Sources generally move toward Galactic center

Sources are slower than Galactic rotation

Abstract

We report trigonometric parallaxes and proper motions of water masers for 12 massive star forming regions in the Perseus spiral arm of the Milky Way as part of the Bar and Spiral Structure Legacy (BeSSeL) Survey. Combining our results with 14 parallax measurements in the literature, we estimate a pitch angle of 9.9 +/- 1.5 degrees for a section of the Perseus arm. The three-dimensional Galactic peculiar motions of these sources indicate that on average they are moving toward the Galactic center and slower than the Galactic rotation.