The active RS CVn-type system SZ Pictoris

Abstract

We study the short-term variability and long-term variability of the spectroscopic binary SZ Pictoris, a southern RS CVn-type system. We used mid-resolution Echelle spectra obtained at Complejo Astronómico El Leoncito spanning 18 yr, and the photometric data from the All Sky Automated Survey data base (V band) and from the Optical Robotic Observatory (BVRI bands) for similar time lapses. We separated the composite spectra into those corresponding to both components, and we were able to determine accurate orbital parameters, in particular an orbital period of 4.95 d. We also observed a photometric modulation with half the orbital period, due to the ellipticity of the stars. We also found cyclic activity with a period of ∼2030 d, both in the photometry and in the Ca II flux of the secondary star of the system.