On the Radio Emission of Hydrogen Nebulae

Abstract

The interpretation of radio-frequency observations of H II regions is discussed with particular regard for the possible effects of random variations in the electron density and electron temperature through the nebulae. It is shown that such variations serve to alter the optical depth and that the conventional definition of the "emission measure" requires modification if it is to be considered an observable quantity. The radio emission of Strömgren spheres is discussed, and a means of determining their electron temperatures is described. An empirical method for the determination of Strömgren's constant defining the ionized volume as a function of the spectral type and luminosity of the exciting star is described.