An updated model for the Perseus Spiral Arm from Trigonometric Parallax and 3-dimensional kinematic distances of distant massive stars

TL;DR

This study refines the Perseus spiral arm model using new VLBA parallax and proper motion data for masers, improving understanding of its position and structure in the Milky Way.

Contribution

It provides updated measurements of the Perseus arm’s location and pitch angle, integrating new maser data with kinematic distances for a more accurate Galactic model.

Findings

Refined the position and pitch angle of the Perseus spiral arm.

Identified the intersection point of Perseus and Sagittarius arms beyond the Galactic Center.

Provided updated Galactic coordinates for the Perseus arm.

Abstract

We report trigonometric parallaxes and proper motions for three water masers and one methanol maser obtained with the VLBA as part of the BeSSeL Survey. Incorporating these parallaxes with 3-dimensional kinematic distances, we refine the position and pitch angle of the Perseus spiral arm in the 1$^\mathrm{st}$ Galactic quadrant. Extrapolating the Perseus and Sagittarius arm locations to beyond the Galactic Center, we find that they intersect at an approximate Galactocentric azimuth of ${200^\circ}$ and radius of $5.6$~kpc.