Radial velocity is a physical term, which generally refers to the velocity component of the object's motion velocity in the direction of the observer's line of sight, that is, the projection of the velocity vector in the direction of the line of sight.Also called radial velocity.
Chinese name
radial velocity
Foreign name
radial velocity
Same concept
Apparent velocity
Definition
Projection of velocity vector in line of sight direction
The radial velocity is the component of the velocity of the target relative to the reference point on the line between them.
also calledApparent velocityThat is, the movement speed of the object or celestial body in the direction of the observer's line of sight.Generally, it refers to the velocity component of the object's velocity in the direction of the observer's line of sight, that is, the velocity vector in the direction of the line of sightProjection。Traditionally, a positive apparent velocity indicates that the object is receding, and if it is negative, the object is approaching.
The concept of radial velocity is often used in astrophysics and radar meteorology.
measuring principle
Announce
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Radial velocity measurement is a method to indirectly detect planets by measuring the disturbance of planets to stars. It is applicable to a wide range of detection objects. Therefore, compared with other extrasolar planet detection methods, radial velocity measurement has found the most extrasolar planets.
Basic principle of radial velocity measurement
The basic principle of radial velocity measurement is shown in the right figure.When the planet rotates around the star, its gravity acts on the star, making the star rotate around the common mass center M of the star and the planet.The velocity component of the star's movement in the observation direction, namely the radial velocity, is a periodic signal determined by the period of the planet's movement. Its amplitude is determined by the mass of the star, the mass of the planet, the distance between the star and the planet, the angle between the normal of the planet's orbital plane and the observation direction and other parameters.
For a star the size of the sun, when Jupiter moves at five AU distances, the magnitude of the star's radial velocity is 12.7m/s;When Neptune moves at a distance of 1 AU, the radial velocity amplitude of the star is 1.5m/s;When the super earth (5 times the mass of the earth) moves at one AU distance, the magnitude of the star's radial velocity is 0.45m/s;When the Earth moves at a distance of AU, the radial velocity of the star is only 9 cm/s.This movement of the star will cause its spectralDoppler shift。When the star moves to point A, the spectrum will occurblue shift；When the star moves to point B, the spectrum will occurred shift。The magnitude of Doppler shift is directly related to the radial velocity.The information about planets can be obtained by observing the Doppler shift of the stellar spectrum.[1]
