An almost complete survey of 21-centimeter line radiation for galactic latitudes of at least 10 deg. VI - Energetic expanding H I shells

Abstract

H I, when viewed in narrow velocity ranges, is concentrated in arcs with typical diameters of tens of degrees. In some cases the diameters change with velocity in the manner expected for expanding shells. The clearest example appears to be consistent with a model involving an old supernova explosion. Much of the interstellar volume is probably contained with H I shells. (AIP)