Monitoring Active Stars 29 Dra, 12 Cam and Colour Excess of Ii Peg
نویسندگان
چکیده
We present the BV light curves analysis of late-type, long-period stars 29 Dra, 12 Cam for the season 2005/2006, and shorter-period star II Peg for the same season. High latitude spots (alternatively spot configuration) cooler than surrounding photosphere were able to explain the light curves. The II Peg colourindex shift in H-R diagram is probably a consequence of stellar metallicity. Other associated mechanisms are briefly discussed.
منابع مشابه
Environments of active close binaries
High-resolution spectroscopic observations were obtained for two eclipsing active close binary systems, GK Hy-drae and TY Pyxidis. For GK Hya excess emission was observed in the Balmer lines and Mg i b lines while TY Pyx showed excess emission in the Balmer lines and Ca ii H & K lines. The emission from GK Hya arises from a global phenomenon associated solely with the secondary component. The l...
متن کاملSerendipitous discovery of an irregular and a semi-regular type variable in the field of BY Draconis
We present new evidence of the optical variability of two red giant stars: HD 172468 and HK Dra, based on photometric and spectroscopic observations. These stars had been included as check stars in our photometric monitoring program of BY Dra and turned out to be variable. HD 172468, whereas almost constant for most of the time, suddenly started to drop in brightness to such a low level to beco...
متن کاملMultiperiodic light variations of active stars
We studied the long-term light behaviour of ten rapidly-rotating active stars (LQ Hya, V833 Tau, EI Eri, V711 Tau, BY Dra, HU Vir, IL Hya, VY Ari, HK Lac, IM Peg) with Fourier analysis. Using photometric databases of up to 30 years in length, we search for periodic or quasi-periodic long-term variations of the overall light levels. Out of the ten stars studied, nine show cyclic variability and ...
متن کاملSpots , plages , and flares on λ Andromedae and II Pegasi ⋆
Aims. We present the results of a contemporaneous photometric and spectroscopic monitoring of two RS CVn binaries, namely λ And and II Peg. The aim of this work is to investigate the behavior of surface inhomogeneities in the atmospheres of the active components of these systems which have nearly the same temperature but different gravity. Methods. The light curves and the modulation of the sur...
متن کاملDepletion in post - AGB stars with a dusty disc . II . ⋆
We present a chemical abundance analysis on the basis of high signal-tonoise and high resolution spectra for 12 stars of our newly defined sample. The selection criterion for the stars of this sample was their position in the ‘RVTauri’ box in the [12] − [25], [25] − [60] two-colour diagram. An additional requisite was the presence of a near-IR excess. We found that the photospheres of nine star...
متن کامل