A typical Doppler shift in the center of a granular cell compared to the "rest" wavelength is 8.75 *10^-4 nm. Take the rest wavelength to be the H_α line of 656 nm. What is the corresponding material speed in the center of the cell?

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Quizplus · Accepted Answer

The Doppler shift formula is $\Delta \lambda = \lambda_0 \frac{v}{c}$, where $\Delta \lambda$ is the change in wavelength, $\lambda_0$ is the rest wavelength, $v$ is the velocity of the object, and $c$ is the speed of light. Given $\Delta \lambda = 8.75 \times 10^{-4}$ nm and $\lambda_0 = 656$ nm, solving for $v$ gives a speed in the order of hundreds of meters per second, which is 0.4 km/s.

A Typical Doppler Shift in the Center of a Granular