CHARA images of the rapidly rotating star Alderamin Stellar rotation causes a star's shape to be flattened at the poles and bulged at the equator. Because the equator is further from the center of the star, it will appear cooler than the poles, an effect called "gravity darkening". The left panel shows the contours of local brightness temperature. To help visualize the geometry of Alderamin, the right panel shows its latitude and longitude. The white circle at the bottom-left corner of the left panel shows the size of the convolving beam that we use for the image reconstruction.
Click here to compare Alderamin to other rapidly rotating stars.
Reference:
Imaging and Modeling Rapidly Rotating Stars: α Cephei and α Ophiuchi
Zhao et al. 2009, ApJ, 701, 209