Radial velocity

Definition

Radial velocity is the component of a star's or other celestial object's velocity that is directed along the line of sight of an observer. It can be measured by observing Doppler shifts in the object's spectral lines.

5 Must Know Facts For Your Next Test

1. Radial velocity helps determine whether a star or object is moving towards or away from Earth.
2. Positive radial velocity indicates the object is moving away, while negative radial velocity means it is approaching.
3. It is calculated using the Doppler Effect, which shifts spectral lines depending on motion.
4. Radial velocity measurements are crucial for identifying exoplanets and binary star systems.
5. Changes in radial velocity over time can reveal orbital parameters and masses of celestial bodies.

Review Questions

• How does radial velocity indicate a star's movement relative to Earth?
• What role does the Doppler Effect play in measuring radial velocity?
• Why are changes in radial velocity important for detecting exoplanets?

Related terms

Doppler Effect:

The change in frequency or wavelength of a wave in relation to an observer moving relative to the source of the wave.

Spectral Line: A dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light at specific wavelengths by substances.

Binary Star System: A system where two stars orbit around their common center of mass, often detectable through variations in their radial velocities.