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Time series analysis of V 368 Cephei photometry
Our time series analysis of {{V 368 Cep}} photometry ascertains therotation period of 2.74d uniquely. The manifestations of starspotinduced luminosity variations in this chromospherically active starinclude rapid light curve changes and differential rotation of about 3%.We conclude that the single rapidly rotating variable {{V 368 Cep}} is ahigh inclination K1{v} post T Tauri star. Table~5 is only available inelectronic form at CDS via anonymous ftp to edarc.u-strasbg.fr(130.79.1285) or via http://cdsweb.u-strasbg.fr/Abstract.html
| Photospheric activity of HD 220140, the optical counterpart of the X-ray source H 2311+77
We present and discuss the photoelectric observations of HD 220140obtained at Merate Observatory and compare them with the ones obtainedby Bianchi et al. (1991). The star shows a variable light activity witha fundamental period of 2.766 d. At the epoch of our observations thelight curve was double-wave shaped, while at the epoch of the Bianchi etal. (1991) data it was essentially a single wave. The light curvevariability as well as the changing mean brightness of the star observedin our data can be explained by the rotation of a star with at least twogroups of photospheric dark spots, whose extent and/or location ischanging with characteristic time-scales of a few rotational cycles.
| The nature of HD220140 from optical and IUE observations
Results are reported from photometric observations of the opticalcounterpart of H2311 + 77 that Pravdo et al. (1985) suggested to be anew RS CVn star. The claim of Poretti et al. (1985) of a photometricperiod of 0.5767 days for this object is disproved by the data obtained.Observations with the IUE satellite at different phases of the lightcurve indicate a value of 2.76 days. The UV spectrum of HD220140 shows acontinuum longwards of 2400 A, and several emission lines from thechromosphere and transition zones, with fluxes comparable to RS CVn orFK Comae stars of the lowest activity level. Optical spectra indicate atype K2V, little velocity variability, and V sin i = 13 km/s, suggestingthat the star, if it is single, is probably a young object, most likelya BY Dra star.
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