HI Absorption Toward HII Regions at Small Galactic Longitudes

Authors :: Jones, C.
Dickey, J. M.
Dawson, J. R.
McClure-Griffiths, N. M.
Anderson, L. D.
Bania, T. M.
Publication Year :: 2013
Abstract: We make a comprehensive study of HI absorption toward HII regions located within Galactic longitudes less than 10 degrees. Structures in the extreme inner Galaxy are traced using the longitude-velocity space distribution of this absorption. We find significant HI absorption associated with the Near and Far 3kpc Arms, the Connecting Arm, Banias Clump 1 and the H I Tilted Disk. We also constrain the line of sight distances to HII regions, by using HI absorption spectra together with the HII region velocities measured by radio recombination lines.<br />Comment: Complete figure set available in online version of journal. Accepted by ApJ August 8, 2013