ABSTRACT

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ABSTRACT: Proper motions and radio structure of the HII component near Sgr A* have been determined based on high resolution (0.1") observations at 13 and 7 mm in the past 7 years (1991-1998). Large proper motions up to 30 mas/yr (or 1200 km/s) have been observed for a number of prominent features. The large proper motion measured from the compact HII components can be explained by motions of a clumpy HII gas accelerated by either strong winds and outflows or explosive events at the Galactic center. Large pattern speeds due to wave or shock motions in the circumnuclear medium at the Galactic center can also be responsible for part of the observed proper motions. In addition, the HII components near Sgr A* (within the central 2.5" or 0.1 pc) show filamentary structures suggesting that the HII components are tidally disrupted by tides due to the concentration of mass at the Galactic center. High precision measurements of the proper motions for these HII components can be used to track the motions of the accreting gas in close proximity to the super massive black hole apparently associated with Sgr A*.