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Volume 344 - 14th European VLBI Network Symposium & Users Meeting (EVN2018) - Astrometry Session
Where are you, Scutum? Tracking down a spiral arm with maser astrometry
K. Immer,* J. Li, L.H. Quiroga-Nuñez, M.J. Reid, B. Zhang, L. Moscadelli
*corresponding author
Full text: Not available
In these proceedings, we discuss the parallax and proper motion measurements towards 43 high-mass star
forming regions in the Scutum spiral arm. These observations were conducted with the Very Long Baseline Array within
the framework of the Bar and Spiral Structure Legacy (BeSSeL) survey. The pitch angle of the spiral arm was found to be
18.6$^{\circ}$ $\pm$ 2.9$^{\circ}$, which is much larger than in other spiral arms.
In this arm, many sources have large peculiar motions, especially a group between $l$=29$^{\circ}$
and 32$^{\circ}$ which shows ordered motion > 25 km s$^{-1}$ towards the Galactic Center.
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