Title: The 2006/2007 photometric activity of three chromospherically active stars: V2075 Cyg, FG UMa and BM CVn
Abstract: We present new multiband CCD photometric observations of three chromospherically active stars with long periods (V2075 Cyg, FG UMa and BM CVn). The observations were made at the Canakkale Onsekiz Mart University Observatory in 2006 and 2007. We analyzed BVRI (Bessell) CCD observations of these three RS CVn-type SB1 binaries with the following three steps: (i) Photometric rotation periods were obtained by analyzing their light variations with a differential corrections method and a Fourier transform technique. (ii) Light variations, observed over three or more consecutive orbital cycles, were investigated by using dark (cool) spot models with the program SPOT. (iii) Surface differential rotation coefficients for the primary components of these binaries were derived using our own photometric periods together with orbital periods taken from the literature. Many photometric observations of non-eclipsing solar and latetype binary stars establish distinct light variations with quasi-sinusoidal forms. Since these late-type stars have strong magnetic fields, their light variations, other than eclipses and proximity effects, are explained in terms of cool/dark spot models. Furthermore, the primary components could be taken as mainly responsible for the observed light variations, because of their predominating luminosities. Spot models provide some important basic results: a photometric rotation period (not necessarily equal to the orbital period) and representative dimensions and temperatures of spots. This observational evidence can be used to understand stellar magnetic activity and test related theoretical models. Such outcomes of photometric investigations of late-type binary stars (including non-eclipsing systems) are among the main motivations of the present study. We have presented photometric analyses of the three chromospherically active binary (CAB) stars (V340 Gem, SAO 62042 and FI Cnc) in our previous paper (Erdem et al., 2009). In the present work, we again select three CAB stars,
Publication Year: 2009
Publication Date: 2009-02-22
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 6
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