Synergetic Spot Mapping via Simultaneous Doppler Imaging and TESS Photometry

The latitudinal distribution of stellar magnetic activity is a fundamental parameter for understanding stellar dynamos, yet it remains poorly constrained by observations. We present a reliable surface spot reconstruction of the young, rapidly rotating K2-type star PW And, utilizing a synergetic approach of spectroscopic and photometric observations. Using the SpotDIPy code, we performed simultaneous Doppler imaging and Light-curve inversion (DI+LCI) by integrating high-resolution GAOES-RV spectra from the 3.8 m Seimei telescope with high-precision TESS photometry. Our analysis reveals prominent spot features at mid-to-low latitudes, equatorial regions, and the southern hemisphere, all of which are regions where DI-only solutions typically fail to provide reliable information. 

Simulations with synthetic spots further demonstrate that the DI+LCI approach significantly enhances the recovery of both spot latitudes and filling factors, particularly in cases of incomplete phase coverage or low signal-to-noise ratios. Furthermore, we investigate the spatial correlation between the reconstructed spot maps and flares detected in the TESS light curve, indicating a potential association between flare occurrences and specific stellar longitudes. These results demonstrate that combining DI with continuous photometry not only improves the inversion accuracy of starspot distributions but also provides critical insights into the spatial origins of stellar flare activity.