Simultaneous Optical Spectroscopy and TESS Photometry of the Active K-type Star PW And

We investigate the relationship between magnetic activity and chromospheric emissions in the active K-type star PW And. By combining high-cadence TESS photometry with simultaneous ground-based spectroscopy from the Nayuta telescope (Nishi-Harima Astronomical Observatory), we monitored Ha and Ca II Infrared Triplet (IRT) lines over two periods in 2022 and 2024.

Our results reveal a clear anti-correlation between the TESS light curve and Ha intensity, suggesting that Ha emission is dominated by plage regions associated with starspots. In contrast, the Ca II IRT lines showed weaker correlation with the rotational phase, indicating different sensitivity to spot-induced variations. 
While starspot coverage increased in 2024 compared to 2022, the average chromospheric emission levels remained stable, pointing to complex activity timescales. 
We also discuss the correlation between Ha and Ca II 8542A core intensities as an indicator of localized atmospheric heating. These findings demonstrate the importance of multi-wavelength, simultaneous observations in characterizing the magnetic activity of K-type stars.