AAS 195th Meeting, January 2000
Session 5. Looking Towards The Galactic Center
Display, Wednesday, January 12, 2000, 9:20am-6:30pm, Grand Hall

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[5.01] Infalling Gas onto the Circumnuclear Disk

R. S. McGary, P. T.P. Ho (Harvard-Smithsonian Center for Astrophysics)

It has been theorized that Sgr A* is fueled by infalling gas and dust from the circumnuclear disk (CND) located at a radius of 2 pc from the black hole. However, the formation and stability of the CND is unclear. The observed CND is not a smooth homogeneous ring with a constant velocity gradient. Rather, it is clumpy implying that it may be a transient feature at the center of our Galaxy.

We have observed ammonia emission near the Galactic center in order to study the structure of the CND and understand how it was formed. This project is a follow-up to work done by Coil & Ho (1999) in which ``streamers'' were found to possibly link nearby giant molecular clouds to the CND. These streamers could provide the CND with the gas and dust necessary to feed Sgr A*.

Observations have been made of the (3,3) rotational transition of NH3 in the region surrounding the Galactic center. Using the Very Large Array, a mosaic of five 2' pointings provides full spatial coverage of the central 10 parsecs of the Galaxy. These observations cover the full velocity range of the CND (±110 km/s from vlsr) enabling all parts of the CND to be imaged.

The previously detected ``southern streamer'' is clearly seen in the data as are indications of new streamers, especially towards the southwest quadrant of the CND. Increased velocity of gas and broadened lines as streamers approach the CND support infall onto the disk. Images of the streamers as well as position-velocity diagrams and line widths can be viewed in this poster.

The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

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