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Dynamical Effects in the Central Region of the Galaxy

Published online by Cambridge University Press:  12 April 2016

Robert H. Sanders
Robert H. Sanders*
Affiliation:
Kapteyn Astronomical Laboratory, Groningen, The Netherlands

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For the purpose of this Paper, I will define the central region of the galaxy as being the inner four kiloparsecs. I make this definition for three reasons:

1) Outside of four kiloparsecs, the rotation curve for the galaxy is well-defined by the Schmidt disk model; whereas, inside four kiloparsecs, the effects of a central spherical component on the rotation curve become conspicuous. This inner spheroid is a dynamical component of the galaxy which is distinct from the disk and may be distinct from the extended halo component as well.

2) There is a conspicuous hole in the total gas density distribution inside 4 kpc.

3) High peculiar or non-circular gas velocities are observed within the inner 4 kpc; velocities ranging from the 53 km s-1 of the so-called 3 kpc arm, to 165 km s-1 in the molecular clouds within 300 pc of the center.

I will now discuss these points in some greater detail.

Type
Part II: Evolution of the Central Parts of the Galaxy
Information
International Astronomical Union Colloquium , Volume 45: Chemical and Dynamical Evolution of our Galaxy , September 1977 , pp. 103 - 113
Copyright
Copyright © Geneva Observatory 1977

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