Astrometry of Star Forming Region IRAS 05137+3919 in the far outer Galaxy

TL;DR

This study uses VERA astrometry to measure the distance to the far outer Galaxy star-forming region IRAS 05137+3919, confirming its location beyond 15 kpc from the Galactic center despite large uncertainties.

Contribution

First direct parallax measurement of IRAS 05137+3919, establishing its position in the far outer Galaxy beyond 15 kpc from the Galactic center.

Findings

Parallax of 0.086 +/- 0.027 mas measured

Distance constrained to >8.3 kpc from Sun

Source confirmed in the far outer Galaxy

Abstract

We present the results of astrometric observations with VERA toward the H2O maser sources in IRAS 05137+3919, which is thought to be located in the far outer Galaxy. We have derived the parallax of \pi = 0.086 +/- 0.027 mas, which corresponds to the source distance of D=11.6+5.3-2.8 kpc. Although the parallax measurement is only 3-sigma level and thus the distance uncertainty is considerably large, we can strongly constrain the minimum distance to this source, locating the source at the distance from the Sun greater than 8.3 kpc (or 16.7 kpc from the Galaxy's center) at 90% confidence level. Our results provide an astrometric confirmation that this source is located in the far outer Galaxy beyond 15 kpc from the Galaxy center, indicating that IRAS 05137+3919 is one of the most distant star-forming regions from the Galaxy center.