A High-Resolution Longitude-Velocity Study of the Galactic Midplane

S. J. Gibson, J. M. Stil (U. of Calgary)

AAS Program Entry [#50.02]

Electronic Poster

The global distribution of neutral atomic hydrogen (H I) is a sensitive probe of Galactic structure. Single dish 21cm studies have revealed large-scale phenomena like the Galactic warp and the flaring of the H I disk, but limited angular resolution has prevented the examination of features smaller than a few hundred parsecs in the outer parts of the disk.

We are conducting a new investigation of the structure of the Galactic disk using 21cm synthesis data from the Canadian Galactic Plane Survey. The CGPS resolution of ~ 1 arcminute permits a much more detailed examination of Galactic H I structure. We use this resolution to define the H I midplane as a surface in (l,b,v) space with the full precision allowed by the CGPS data. This determination allows us to extract high-resolution longitude-velocity diagrams passing through the true midplane of the Galaxy and at fixed angles offset from it. Applications of our results include the study of new small-scale features of Galactic structure, kinematics of H I clouds in the disk potential, and establishing the context of H I absorption features used to probe neutral gas properties.

This work is supported by a grant from the Natural Sciences and Engineering Research Council of Canada.