Suppose that two stars are identical in every way-for example,same distance,same mass,same temperature,same chemical composition,and same speed relative to Earth-except that one star rotates faster than the other.Spectroscopically,how could you tell the stars apart?
A)The faster rotating star has wider spectral lines than the slower rotating star.
B)The faster rotating star will have an emission line spectrum while the slower rotating star will have an absorption line spectrum.
C)The peak of thermal emission will be at a shorter wavelength for the faster rotating star than for the slower rotating star.
D)There is no way to tell the stars apart spectroscopically,because their spectra will be identical.

Question

Quizplus · Accepted Answer

The faster rotating star will have broader spectral lines due to the Doppler shift of the rotation. The rotation causes the gas on the star's equator to move towards the observer, causing a blueshift in the spectral lines, and away from the observer causing a redshift in the spectral lines. This broadening of spectral lines is called rotational broadening. Therefore, the faster rotating star will have wider spectral lines than the slower rotating star.

Suppose That Two Stars Are Identical in Every Way-For Example,same