Constraining the Spiral Arm Structure in the Outer Galaxy

Michael Rugel

Thursday, Dec. 5th, 10:00CET

Over the past decades, our understanding of the Milky Way’s large-scale spiral structure has significantly improved through parallax maser distance measurements. The locations and the morphology of the Outer and Outer-Scutum-Centaurus arms, however, remain poorly constrained. As an extension to the BeSSeL survey, we measure parallaxes of water masers at 22 GHz in high-mass star forming regions in the Outer Galaxy, which are tracers of spiral structure. We present results on the parallax of G98.03+1.44, to date the most distant maser parallax measured in the second quadrant of the Galaxy. We discuss the source's location with respect to the Outer and Outer-Scutum-Centaurus arms. We give an outlook on the remaining, as well as implications on spiral arm models.