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HI at the outer edge of the Galaxy and its implications for Galactic rotation

Published online by Cambridge University Press:  04 August 2017

Peter D. Jackson
Peter D. Jackson*
Affiliation:
Department of Physics, York University Downsview, Ontario Canada

Extract

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In their analysis of global properties of the Galaxy based on the HI distribution outside of the solar circle, Knapp, Tremaine, and Gunn (1978 - hereafter referred to as KTG) have examined the extreme HI velocities for the outer edge of the Galaxy. They fit these values to a model based on an exponential drop-off of HI surface density with galactocentric radius, R, and a flat rotation curve. Adopting a value of 4 kpc for the scale length, L, of this drop-off, KTG fit the extreme velocities with various values of θo (the circular rotation speed of the Local Standard of Rest), to obtain a best fit of θo − 220 km/s. While KTG obtained sensitive observations with the NRAO 43-m radio telescope for the galactic-longitude range 1 = 80° to 225°, they had to rely on the HI survey by Kerr, Harten, and Ball (1976 - hereafter referred to as KHB), obtained with the Australian 64-m radio telescope at Parkes, for the balance of the Southern Milky Way.

Type
PART II: COMPOSITION, STRUCTURE AND KINEMATICS
Information
Symposium - International Astronomical Union , Volume 106: The Milky Way Galaxy , 1985 , pp. 179 - 180
Copyright
Copyright © Reidel 1985 

References

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