A Radio Survey of the Southern Milky Way at a Frequency of 1440 Mc/s. II. The Continuum Emission from the Galactic Disk

Abstract

The 1440 Mcls survey (Part I of this series) has been used in conjunction with the 85·5Mc/s survey of Hill, Slee, and Mills (1958) to delineate the distribution of the thermal and nonthermal radiation from the disk component of the Southern Milky Way and so complete an investigation commenced by the Northern Hemisphere observers Westerhout (Leiden) and Large, Mathewson, and Haslam (Jodrell Bank). Results of the analysis show an intense concent,ration of ionized hydrogen in an irregular spiral structure in the inner regions of the Galaxy. From lII=256° to 88°, good agreement was obtained between the longitudes at which concentrations of neutral hydrogen were found to occur from H-line studies and the longitudes at which the ionized hydrogen was concentrated. The steps in the longitude distribution of the 85·5 Mcls radiation which Mills used to delineate the spiral arms of the Galaxy were not all visible in the longitude distribution of the nonthermal component obtained from this present analysis. It is believed that three of Mills's steps are thermal in origin.