Sigma Geminorum is a magnetically active star that was imaged with CHARA Array over its 19.6 day rotational period.
Surface images of sigma Geminorum from 2011 (left) and 2012 (right). The Aitoff projections show the surface temperature with the appropriate color scale to the right of the projection. The latitudes hidden by stellar inclination appear above the dashed line around the top pole. Each contour represents 100 K. The gray bar beneath the Aitoff projection represents the number of times each phase was observed with MIRC, with darker grays indicating more observations.
Reference:
Contemporaneous Imaging Comparisons of the Spotted Giant σ Geminorum Using Interferometric, Spectroscopic, and Photometric Data
Roettenbacher, R., et al., 2017, Astrophysical Journal, 849, 120