On the Location of Radio and X-Ray Emission in the Algol System

Abstract

The radio behaviour of Algol at centimeter wavelengths has been reviewed by Hjellming (1976, 1977), and by Gibson (1976). The observed radio emission can be roughly divided into two types: a quiescent type and a flare-like or outburst type. The quiescent emission is characterized by a low flux density, usually between 20 − 50 mJy, and a nearly flat spectral index. The latter means that the value of the flux density is nearly independent of wavelength. The variations in flux density, when present, are gradual and have a time scale on the order of days. The flare-like behaviour shows rapid and large changes in flux density. The amplitude of an outburst is wavelength dependent, the shorter wavelengths having larger amplitudes. Woodsworth and Hughes (1976, hereafter WH) attributed the two types of behaviour to two physically distinct sources. The quiescent type of emission is produced by a very large, thermally emitting cloud which surrounds the eclipsing system. The flare-like variations are due to a synchrotron source that is associated with mass loss. Their model is inconsistent with optical and X-ray information concerning the Algol system. However, a model with two radio components can be modified to agree with other types of data.