Spotted surface structure of the active giant PZ Mon

TL;DR

This study characterizes the surface features of the active red giant PZ Mon, revealing a stable polar spot and warm spots that influence its brightness variations, based on photometric observations and modeling.

Contribution

The paper provides a detailed three-spot model of PZ Mon's surface, including a stable polar spot and warm spots, based on combined observational data and analysis.

Findings

Identified a stable polar spot responsible for long-term brightness variations.

Determined the spot temperatures and coverage areas on PZ Mon.

Confirmed the presence of the polar spot through molecular band analysis.

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 Teff=4730K, the spot temperature Tspot=3500K, 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 about 3500K as well as large and small warm spots with a temperature of about 4500K. The stable polar spot is responsible for the long-period brightness variations. Its presence is confirmed by an analysis of the TiO 7054$~\AA$ 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.