An investigation of the magnetic activity of HD 134319 based on TESS photometry and ground-based spectroscopy

TL;DR

This study analyzes the magnetic activity and starspot behavior of HD 134319 using TESS photometry and ground-based spectroscopy, revealing evolving starspot configurations and magnetic activity indicators over multiple years.

Contribution

It introduces a combined photometric and spectroscopic analysis revealing starspot evolution and magnetic activity patterns on HD 134319, with a focus on two-spot modeling and chromospheric emission correlations.

Findings

Two-spot configuration explains observed data

Significant evolution in spot radii and magnetic activity indicators

Correlated chromospheric emissions with rotational modulation

Abstract

We present analysis of the starspot properties and chromospheric activity on HD 134319 using high precision photometry by TESS in sectors 14-16 (T1), 21-23 (T2) and high-resolution spectroscopy by OHP/ELODIE and Keck/HIRES during years 1995-2013. We applied a two-spot model with GLS determined period $P=4.436391\pm0.00137$ day to model chunks sliding over TESS light curve, and measured relative equivalent widths of Ca II H and K, H$\beta$ and H$\alpha$ emissions by subtracting overall spectrum from individual spectrum. It was found that a two-spot configuration, i.e. a primary, slowly evolving and long-lasting spot (P) plus a secondary and rapidly evolving spot (S), was capable of explaining the data, although the actual starspot distribution is unable to derived from collected data. Despite the spot radius-latitude degeneracy revealed in the best-fit solutions, a sudden alternation between P and S radii followed by gradual decrease of S in T1 and the decrease of both P and S from T1 to T2 were significant, corresponding to the evolution of magnetic activity. Besides, S revealed rotation and oscillatory longitude migration synchronized to P in T1, but held much larger migration than P in T2. This might indicate the evolution of internal magnetic configuration. Chromospheric activity indicators were found to tightly correlated with each other and revealed rotational modulation as well as a long-term decrease of emissions, implying the existence and evolution of magnetic acitivity on HD 134319.