Altair possesses an extremely rapid rate of rotation; it has a rotational period of approximately 9 hours. For comparison, the equator of the sun requires just over 25 days for a complete rotation. This rapid rotation forces Altair to be oblate, its equatorial
diameter is over 20 percent greater than its polar diameter. Below image
False-color image of the rapidly rotating star Altair, made with the MIRC imager on the CHARA array on Mt. Wilson

Image from Wikipedia


