The red supergiant RS Per is located in the Perseus OB1 association. The CHARA image shows the detection of a "dark spot" on the red supergiant RS Per that probably corresponds to cooler granulation.

Reference:

CHARA/MIRC Observations of Two M Supergiants in Perseus OB1: Temperature, Bayesian Modeling, and Compressed Sensing Imaging (pdf)
Baron, F., et al., 2014, Astrophysical Journal, 785, 46