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We present the case of hot semi-detached Algols showing photometric cycles longer than the orbital period. The evidence indicating that this long cycle might be due to a magnetic dynamo operating in the rapidly rotating donor star is examined. [ABSTRACT FROM AUTHOR]

The detection and analysis of line emission of the CaII, H(396.8nm) and K(393.3nm) have confirmed the chromospheric activity of some single and binaries stars. This activity is associated to the presence of magnetic fields which in turn are produced by internal convective flows along with stellar rotation producing a long-term photometric cycle length related to the apparition and vanishing of superficial stellar spots. We present a photometric study of stars of the type RS CVn, Rotationally variable Star and BY Dra, that have shown evidence of chromospheric activity. The analysis of these measurements has allowed us to delimit periods of rotation. In addition, we have detected and measured the cycle length in some cases. It allows us to complement previous investigations and in some cases to determine for the first time the presence of a long photometric cycle, contributing to complement the link between rotation and magnetic cycles. [ABSTRACT FROM AUTHOR]

We present the case of hot semi-detached Algols showing photometric cycles longer than the orbital period. The evidence indicating that this long cycle might be due to a magnetic dynamo operating in the rapidly rotating donor star is examined. [ABSTRACT FROM AUTHOR]

The detection and analysis of line emission of the CaII, H(396.8nm) and K(393.3nm) have confirmed the chromospheric activity of some single and binaries stars. This activity is associated to the presence of magnetic fields which in turn are produced by internal convective flows along with stellar rotation producing a long-term photometric cycle length related to the apparition and vanishing of superficial stellar spots. We present a photometric study of stars of the type RS CVn, Rotationally variable Star and BY Dra, that have shown evidence of chromospheric activity. The analysis of these measurements has allowed us to delimit periods of rotation. In addition, we have detected and measured the cycle length in some cases. It allows us to complement previous investigations and in some cases to determine for the first time the presence of a long photometric cycle, contributing to complement the link between rotation and magnetic cycles. [ABSTRACT FROM AUTHOR]

We present a spectroscopic and photometric study of the interacting binary and Double Period Variable HD 170582 based on the analysis of the ASAS V-band light curve and our high-resolution spectra mostly obtained with CHIRON spectrograph at the 1.5m CTIO telescope. [ABSTRACT FROM PUBLISHER]