Spotted Surface Structure of the Active Giant PZ Mon

Abstract

Based on our photometric observations in 2015–2016 and archival photometric data for the active red giant PZ Mon, we have found the main characteristics of the stellar surface: the unspotted surface temperature T_eff = 4730 K, the spot temperature T_s = 3500 K, and the relative spot area from 30 to 40%. The best agreement with the observations has been achieved in our three-spot model including a cool polar spot with a temperature of ~3500 K as well as large and small warm spots with a temperature of ~4500 K. The stable polar spot is responsible for the long-period brightness variations. Its presence is confirmed by an analysis of the TiO 7054 Å molecular band. The small-amplitude 34-day variability is attributable to the warm spots located on the side of the secondary component, which determine the relatively stable active longitude.