Discrete Sources of Cosmic Radio Waves

Abstract

One of the principal features of the distribution over the sky of cosmic radio-frequency radiation is the presence of localized sources of relatively high intensity which are described by the term discrete sources. At the present time our knowledge of the nature of these sources is very limited and the description discrete is correspondingly vague. No attempt will be made here to define precisely what is classed as a discrete source, except to state that the term has been applied to sources with an angular extent small compared with the general features of the distribution of radiation over the sky; it has been applied indiscriminately to objects which differ considerably in nature and which may have apparent angular diameters varying from about one minute of arc to about one degree. The more popular term “radio star” has been avoided because the observational evidence of the past decade points to the conclusion that the discrete sources are not associated with bodies of stellar dimensions, but arise in objects, or in regions, of vastly greater size. Radio sources which are associated with the solar system, for example the Sun or the planets Venus and Jupiter, are not included in this article¹.