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Meaning
  1. 1
    English · JMdict
    radial velocity;line-of-sight velocity
  2. 2
    English · Wikipedia

    The radial velocity of an object with respect to a given point is the rate of change of the distance between the object and the point. That is, the radial velocity is the component of the object's velocity that points in the direction of the radius connecting the object and the point. In astronomy, the point is usually taken to be the observer on Earth, so the radial velocity then denotes the speed with which the object moves away from or approaches the Earth. In astronomy, radial velocity most commonly refers to the spectroscopic radial velocity, which is determined by spectroscopy. i.e. by measuring the frequencies of light received from the object. By contrast, astrometric radial velocity is determined by astrometric observations (for example, a secular change in the annual parallax).

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