Radial velocity

Radial velocity

Radial velocity is the velocity of an object in the direction of the line of sight (i.e. its speed straight towards you, or away from you). The light of an object with a substantial radial velocity will be subject to Doppler effect, so the frequency of the light decreases for receding objects (redshift) and increases for approaching objects (blueshift).

The radial velocity of a star or other luminous but distant objects can be measured accurately by taking a high-resolution spectrum and comparing the measured wavelengths of known spectral lines to wavelengths from laboratory measurements. By convention, a positive radial velocity indicates the object is receding; if the sign is negative, then the object is approaching.

In many binary stars, the orbital motion usually causes radial velocity variations of several kilometers per second. As the spectra of these stars vary due to the Doppler effect, they are called spectroscopic binaries. Radial velocity studies can be used to estimate the masses of the stars, and some orbital elements, such as eccentricity and semimajor axis. The same method has also been used to detect planets around stars, in the way that the movement's measurement determines the planet's orbital period, while the resulting size of the displacement allows the calculation of the lower bound on a planet's mass. Radial velocity methods alone may only reveal a lower bound, since a large planet orbiting at a very high angle to the line of sight will perturb its star radially as much as a much smaller planet with an orbital plane on the line of sight.

ee also

*Extrasolar planet
*Proper motion
*Doppler spectroscopy


Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • radial velocity — radialusis greitis statusas T sritis Standartizacija ir metrologija apibrėžtis Greičio sandas, kurio vektorius nukreiptas išilgai kūno sukimosi spindulio. atitikmenys: angl. radial velocity vok. Radialgeschwindigkeit, f rus. радиальная скорость,… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • radial velocity — radialusis greitis statusas T sritis fizika atitikmenys: angl. radial velocity vok. Radialgeschwindigkeit, f rus. радиальная скорость, f pranc. vitesse radiale, f …   Fizikos terminų žodynas

  • RAdial Velocity Experiment — Das RAdial Velocity Experiment (RAVE) ist eine spektroskopische Durchmusterung des Südhimmels. Dazu wird ein Multi Objekt Spektrograf am 1,2 Meter UK Schmidt Teleskop des Anglo Australian Observatory (Australien) benutzt. RAVE ist ein… …   Deutsch Wikipedia

  • radial velocity — /reɪdiəl vəˈlɒsəti/ (say raydeeuhl vuh losuhtee) noun the velocity, usually expressed in kilometres per second, with which a celestial body approaches or recedes from the observer. Also, line of sight velocity …  

  • radial velocity — noun velocity along the line of sight toward or away from the observer • Hypernyms: ↑speed, ↑velocity …   Useful english dictionary

  • radial velocity — noun chiefly Astronomy the velocity of a star or other body along the line of sight of an observer …   English new terms dictionary

  • radial velocity — noun motion of a star toward or away from the earth …   Wiktionary

  • High Accuracy Radial Velocity Planetary Search — High Accuracy Radial velocity Planet Searcher High Accuracy Radial velocity Planet Searcher (HARPS) est un spectrographe équipant le télescope de 3,6 mètres de l observatoire de La Silla et destiné à la recherche d exoplanètes, par la méthode des …   Wikipédia en Français

  • High Accuracy Radial velocity Planetary Search — High Accuracy Radial velocity Planet Searcher High Accuracy Radial velocity Planet Searcher (HARPS) est un spectrographe équipant le télescope de 3,6 mètres de l observatoire de La Silla et destiné à la recherche d exoplanètes, par la méthode des …   Wikipédia en Français

  • High accuracy radial velocity planetary search — High Accuracy Radial velocity Planet Searcher High Accuracy Radial velocity Planet Searcher (HARPS) est un spectrographe équipant le télescope de 3,6 mètres de l observatoire de La Silla et destiné à la recherche d exoplanètes, par la méthode des …   Wikipédia en Français

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”