Long-term starspot activity of the eclipsing binarySV Cam

Abstract

Abstract The paper is devoted to the problem of the determination of the orbital and physical parameters of the active eclipsing binary SV Cam on the basis of the interpretation of photometric observations made by Patkós (1982) during the period 1973–1981. The problem is solved in two stages: by obtaining a synthetic light curve in the case when the parameters of the corresponding Roche model (Djuraŝević, 1992a) are given a priori (direct problem), and by determining the parameters of the model for which the best fit between the synthetic light curve and the observations is achieved (inverse problem) (Djuraŝević, 1992b). A total of 18 light curves are analysed in the framework of the Roche model, involving two spotted regions on the primary component of the system (Sp G3 V), with the temperature contrast between the spotted area and the surrounding photosphere As = Ts/T 1 = 0.65. The basic parameters of the system and of the spotted areas are estimated. According to the obtained results the spotted areas are formed at high latitudes and cover a significant part of the stellar surface. No clear cyclicity of the system's activity is noted from the analysed observations. There are some indications that the spotted area at high latitudes (above 70°) corresponds to an enhanced activity. Since the system's period is short (P ∼ 0.d59), the presence of spotted regions at high latitudes can be explained by the dynamo mechanism for rapid rotators (Schüssler and Solanski, 1992). During the analysed period the spotted areas tend to fall into the specially active longitude sectors at high latitudes, near stellar polar regions. The light curve analysis allowed an estimation of the system's parameters and those of the active spotted regions.