Asymptotic giant branch (AGB) stars are cool luminous evolved stars that have complex stellar surface dynamics. The panels above show reconstructed images of CL Lac at wavelengths of 1.52 μm (left) and 1.70 μm (right). The CHARA images reveal an off-centered bright spot that impacts the position of the photocenter of the star.
Reference:
Optical interferometry and Gaia measurement uncertainties reveal the physics of asymptotic giant branch stars (pdf)
Chiavassa, A., et al., 2020, Astronomy and Astrophysics, 640, 23