How does a star’s rotation affect the appearance of its spectral lines? Hint: Assume we are looking at the star from above its equator. Then, at every instant, half of the spinning star is approaching...

How does a star’s rotation affect the appearance of its spectral lines? Hint: Assume we are looking at the star from above its equator. Then, at every instant, half of the spinning star is approaching Earth, while the other half is receding. Consider the resulting Doppler shift in the spectral lines.