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We present new results based on high-resolution observations of Sgr A West atthe Galactic center with the VLA at 1.3 cm. We measured proper motions for 71compact HII components. We also investigated radial velocities in the LSRvelocity using the H92a line data. Combining proper motion and radial velocitymeasurements, we have determined the 3D velocity distribution in Sgr A West. Wefind that the three ionized streams (Northern Arm, Eastern Arm, and WesternArc) can be modeled with three bundles of Keplerian orbits around Sgr A*. Wedetermined the five orbital parameters for each of them using LSQ fitting tothe locii of the streams. Our results confirm earlier results on the streams inthe Western Arc and the Northern Arm to be in Keplerian orbits, suggesting thatthe stream in the Eastern Arm is also consistent with an elliptical orbit. Boththe Northern and Eastern Arm streams have high eccentricities, while theWestern Arc stream is nearly circular. All three streams orbit around Sgr A* ina counterclockwise sense (viewed from the Earth). We also report an ionizednebula associated with IRS 8, including a bow shock in radio continuum emissionwhich shows excellent agreement with near IR observations. From the H92a linedata, we find evidence for interaction between the IRS 8 nebula and theNorthern Arm stream. Other new morphological features revealed in ourhigh-resolution image include: 1) a helical structure in the Northern Arm,suggesting that MHD plays an important role in the motion of the ionized gas,in addition to the dynamics determined by the central gravitational field and2) a linear feature in the IRS 16 region, suggesting the compressed edge of theNorthern Arm may result from the collective winds and radiation pressure fromthe high mass stars in the IRS16 cluster.

Dynamics of Ionized Gas at the Galactic Center: VLA Observations of the 3D Velocity Field and Location of the Ionized Streams in Sagittarius A West