How do we measure radial velocity of stars?

Question

Lincoln Adams · Accepted Answer

Red or blue shift.

When we examine the light spectrum emitted by a star, we can spot emission or absorption lines that are typical of specific elements but have been doppler-shifted to appear blue (shorter wavelength) or red (longer wavelength). You've probably heard the sound of an emergency vehicle's siren change as it goes by: the sound waves compress as it gets closer to you, producing a higher frequency, and they stretch as it moves away from you, producing a lower frequency. Light has an effect that is comparable. We can determine the radial velocity by calculating the magnitude of the frequency shift.

Ian Ashcroft · Answer

undefined Spectroscopy, and more specifically the Doppler shift in the star's spectral lines, is used to measure the radial velocity of stars.

Madeline Arroyo · Answer

undefined The radial velocity of stars is measured by observing the Doppler shift in the spectral lines of the star's light. This shift occurs due to the star's motion toward or away from the observer. Instruments such as spectrographs are used to analyze the star's spectrum, and the Doppler shift is calculated based on the displacement of spectral lines from their expected positions. This allows astronomers to determine whether a star is moving towards or away from Earth, as well as the velocity of its motion along the line of sight.