Why is the hydrogen line in Rigel's spectrum shifted downward?
The Downward Shift in Rigel's Spectrum
Explanation of the Doppler Effect
The Doppler effect occurs because the motion of the source of light affects the wavelength of the light waves reaching the observer. When Rigel is moving away from us, the frequency of the hydrogen line in its spectrum appears to decrease, causing a downward shift in the spectral line.Calculation of Rigel's Velocity
To calculate Rigel's velocity relative to us, we can use the formula derived from the relativistic Doppler effect. The velocity of Rigel, denoted as vr, can be calculated using the following equation:vr = (f' / f) * c