Compute the full width half maximum of the line profile for a magnesium absorption line of rest wavelength 500 nm on a star spinning with equatorial...

Compute the full width half maximum of the line profile for a magnesium absorption line of rest wavelength 500 nm on a star spinning with equatorial velocity 100 kms-1 and sin(i)=1.  Compare this with the full width half maximum due to thermal broadening if the star's temperature is 8000 K.