This is not the star's disk you are seeing but the effect of having a circular aperture in your telescope and due to the nature of light.

这不是星星自身的光环，而是由于望远镜的圆形孔径光阑以及光的物理特性造成的。

youdao

People in a much larger region of the world can anticipate seeing a partial solar eclipse, in which the moon blocks only a fraction of the sun's disk.

CNN: Africa awaits total eclipse of the sun