To measure the temperature of the flattened stars is used a theorem that it has now been shown that it is incomplete
Left: Detailed surface temperature of Regulus star (a Leonis). Right: Some polar star flattening, from the Sun (weak flattening by 25 days rotation period) to Achernar, with rotating period of hours, close to star fracture limit.
Some examples of flattened stars caused by hight rotating velocities. Shinning regions are hotter, and all of them show higher temperature in polar zones.
A. Claret. On the deviations of the classical von Zeipel´s theorem at the upper layers of rotating stars. Astronomy & Astrophysics (2011, en prensa).
Antonio Claret - claret[at]iaa.es - 958812335