The active RS CVn-type system SZ Pictoris

TL;DR

This study analyzes the long-term variability of the RS CVn-type binary SZ Pictoris using spectroscopic and photometric data, revealing orbital parameters, ellipticity effects, and cyclic activity periods.

Contribution

It provides detailed orbital parameters and uncovers cyclic activity in SZ Pictoris through extensive multi-year spectroscopic and photometric observations.

Findings

Orbital period of 4.95 days determined

Photometric modulation with half the orbital period observed

Cyclic activity period of approximately 2030 days identified

Abstract

We study the short and long-term variability of the spectroscopic binary SZ Pictoris, a southern RS CVn-type system. We used mid-resolution echelle spectra obtained at CASLEO spanning 18 years, and photometric data from the ASAS database 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 days. 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 days, both in the photometry and in the Ca II flux of the secondary star of the system.