Coronal activity from AB Dor and RST 137B

Abstract

Two 12-h synthesis observations of the active star AB Dor (HD 36705) made with the Molongo Observatory Synthesis Telescope (MOST) as part of a 1990 international campaign of observations are presented. A weak variable source was detected near the stellar position during both sessions. The derived brightness temperatures are consistent with a gyrosynchrotron emission model. The complete sample of MOST observations of AB Dor made since 1985 reveals a quiescent level of radio emission with fare-like increases, and a discrepancy of ∼ 5 arcsec between the 843-MHz source and the optical position. An analysis of the variations in position of the radio source with flux density suggests that this discrepancy may be the result of confusion with the nearby, active dMe star RST 137B