The Spiral Structure and Kinematics of the Milky Way
We are conducting a large project (BR100) with the VLBA
to study the spiral structure and kinematics of the Milky Way.
We will accomplish this
by determining distances, via trigonometric parallax, and
proper motions of star forming regions in the Milky Way.
The target sources are 12 GHz methanol masers which are
associated with young massive stars and compact HII regions
that trace spiral structure. With accurate distance measurements
we will locate spiral arms, and with absolute proper motions
we can determine the 3-dimensional motions of these massive
young stars.
Over the past decade, we have developed and tested the
techniques needed to achieve better than 0.05 mas relative positional accuracy
between maser sources and a background QSO at each epoch. As a proof of technique,
we have determined the trigonometric parallax to W3OH with an
accuracy of 0.01 mas and also measured its absolute proper motion
with an accuracy of 1 km/s. We are now conducting similar
observations of a dozen methanol masers, sampling the
Perseus, Sagittarius, Scutum and Norma spiral arms in the first
and second quadrants of the Milky Way.
Project Team
Mark Reid & Lincoln Greenhill: Harvard-Smithsonian Center for Astrophysics
Karl Menten: Max-Planck-Institut fuer Radioastronomie
Ye Xu: Max-Planck-Institut fuer Radioastronomie & Shanghai Astronomical Observatory
Xing Wu Zheng: Nanjing University
Luca Moscadelli: Obs. Astron. Cagliari
Project Overview
Background Information
Project Goals
Demonstration Observations: W3OH
Observational Strategy
Observation Schedule
Observation Plan