Evolutionary status of the active star PZ Mon

TL;DR

This study characterizes PZ Mon as a K2III giant star with a confirmed red giant status, using spectral and photometric data to determine its physical parameters, chromospheric activity, and possible binary nature.

Contribution

The paper provides the first detailed atmospheric parameters and evolutionary status of PZ Mon, clarifying its classification as a red giant and analyzing its activity and potential binarity.

Findings

PZ Mon is a K2III giant star with Teff=4700K and log g=2.8.

Distance estimated at 250±70 pc, smaller than Hipparcos measurement.

Displays chromospheric activity and possible orbital motion evidence.

Abstract

We use original spectra and available photometric data to recover parameters of the stellar atmosphere of PZ Mon, formerly referred as an active red dwarf. The derived effective temperature Teff=4700K and gravity lgg=2.8 suggest that PZ Mon is a K2III giant. Stellar atmosphere parameters (Teff and lgg) alongside with the evolutionary tracks are used to estimate the stellar mass of ~1.5Mo and the radius of ~7.7Ro. The angular radius derived by the infrared flux method when combined with the linear radius suggests the distance of 250+/-70 pc, a factor 2.5 smaller than that suggested by the Hipparcos parallax. The red giant status of PZ Mon is confirmed by the carbon and nitrogen abundance. The spectrum reveals pronounced HeI 5876 A absorption and Halpha emission indicating the robust chromosphere. The IUE spectrum is found to contain transition layer emission line of CIV 1550 A. The CIV and X-ray luminosities turn out typical of RS CVn stars. The extended set of available photometric data confirms the period of 34.14 days presumably related to the stellar rotation. We found variations of the radial velocity with the amplitude of ~8 kms which could be caused by the orbital motion.