Astrometry of Galactic Star-Forming Region G48.61+0.02 with VERA

TL;DR

This study precisely measured the distance and motion of the star-forming region G48.61+0.02 using VLBI astrometry, revealing its location in the Sagittarius-Carina arm and significant peculiar motion.

Contribution

First direct parallax measurement of G48.61+0.02, clarifying its distance and motion within the Galaxy with high precision.

Findings

Distance of 5.03 kpc to G48.61+0.02

Large peculiar motion of 40 km/s

Location in the Sagittarius-Carina arm

Abstract

We performed the astrometry of H2O masers in the Galactic star-forming region G48.61+0.02 with the VLBI Exploration of Radio Astrometry (VERA). We derived a trigonometric parallax of 199+/-7 micro as, which corresponds to a distance of 5.03+/-0.19 kpc. The distance to G48.61+0.02 is about a half of its far kinematic distance, which was often assumed previously. This distance places G48.61+0.02 in the Sagittarius-Carina arm and near the active star forming region and the supernova remnant W51. We also obtained the three dimensional motion of G48.61+0.02, and found that it has a large peculiar motion of 40+/-5 km/s. This peculiar motion would be originated with the multiple supernovae explosions in W51, or the streaming motion across the Sagittarius-Carina arm.