Abstract
We report on the longest-running continuous radio flare survey of two Algol-type systems (β Per and δ Lib) and two RS CVn systems (V711 Tau and UX Ari). All four systems have late-type components, and all were known to display radio flaring activity. The primary aim of the campaign was to determine the timescales for flaring activity in these systems. The radio continuum flux at 2.3 and 8.3 GHz was monitored with the NRAO-Green Bank Interferometer from 1995 January to 2000 October. The survey spanned 2096 days with interruptions during maintenance runs and temporary closings of the interferometer. Many strong flares were detected with continuum fluxes at 8.3 GHz as high as 1.17 Jy in β Per, 1.44 Jy in V711 Tau, and 0.82 Jy in UX Ari. Only two flares were detected from δ Lib during 1123 days of monitoring, and the continuum flux reached a maximum of only 0.034 Jy at 8.3 GHz. The independent techniques of Power Spectrum Analysis and Phase Dispersion Minimization were used to determine the periodicity of flaring activity in each binary. The strongest periodicities found were 48.9 ± 1.7 days for β Per, 120.7 ± 3.4 days for V711 Tau, and 141.4 ± 4.5 days for UX Ari, with other significant periodicities of 80.8 ± 2.5 days for V711 Tau and 52.6 ± 0.7 days for UX Ari. In the case of δ Lib, the strongest periodicities were related to the duration of the two monitoring cycles within the data set and are not real. The continuous survey has demonstrated that there are active and quiescent flaring cycles in V711 Tau and β Per. During both of these cycles, β Per had more flares than V711 Tau, but its strongest flares were typically weaker than those of V711 Tau.
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