A Preliminary Survey of 1420 Mc/s. Line Emission from Galactic Hydrogen

Abstract

A preliminary survey of 1420 Mc/s. hydrogen-line emission has been made over 270° of galactic longitude extending through the galactic centre, and anticentre. The radiation source is in the form of a band of varying intensity along the galactic equator. The maximum brightness temperature is about 100 °K, in the direction of the galactic anticentre. Measurements of line-profile show considerable variation, with a minimum width of 0.12 Mc/s. Double lines are evident between galactic longitudes 170 and 240° and it is suggested that these may originate in major structural features of the Galaxy. The change in the peak brightness of the line along the galactic equator may result from line broadening due to galactic rotation. On the other hand it may reveal the existence of highly emitting regions. The latter interpretation is supported by the agreement in position of the bright areas for both the line emission and the continuous spectrum galactic emission.