Ultraviolet and Radio Observations of Milky Way Halo Gas

Abstract

Interstellar-absorption-line and 21-cm emission-line data for sight lines to 56 stars are combined in order to study the kinematics and spatial distribution of the gas that is at great distances from the Galactic plane. Measurements of the interstellar velocities and H I column densities from the 21-cm emission and Ly-alpha absorption are included. The problem of contamination of the interstellar Ly-alpha absorption line by stellar Ly-alpha absorption is analyzed, and this information is used to reevaluate the vertical distribution of H I. A new method for determining lower limits on the vertical distribution of gas by including information on the velocity structure in the gas is presented. The data for individual sight lines are discussed.