# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 8 Search : Keplerian
 Keplerian   کپلری   KepleriFr.: keplerien   Of or pertaining to Johannes Kepler or to his works or discoveries.From → Kepler + -ian a suffix forming adjectives. Keplerian angular velocity   تندای ِ زاویه‌ای ِ کپلری   tondâ-ye zâviye-yi-ye KepleriFr.: vitesse angulaire keplérienne   The angular velocity of a point in a circular orbit around a central mass. It is given by: ΩK = (GM/r3)1/2, where G is the → gravitational constant, M is the mass of the gravitating object, and r is the radius of the orbit of the point around the object.→ Keplerian; → angular; → velocity. Keplerian disk   گرده‌ی ِ کپلری، دیسک ِ ~   gerde-ye Kepleri, disk-e ~Fr.: disque keplérien   A circumstellar disk (such as an → accretion disk or a → protoplanetary disk) in which the → angular velocity at each radius is equal to the angular velocity of a circular → Keplerian orbit at the same radius. The main characteristic of the Keplerian disk is that → orbital velocity varies as r-1/2. This means that an object on an orbit closer to the central mass turns more rapidly than that on a farther orbit. This velocity difference is at the origin of internal friction or kinematic viscous forces between disk particles, which heats up the material.→ Keplerian; → disk. Keplerian orbit   مدار ِ کپلری   madâr-e Kepleri (#)Fr.: orbit keplérienne   The orbit of a spherical object of a finite mass around another spherical object, also of finite mass, governed by their mutual → gravitational forces only.→ Keplerian; → orbit. Keplerian orbital velocity   تندای ِ مدار ِ کپلری   tondâ-ye madâr-e KepleriFr.: vitesse d'orbite képlérienne   The velocity of an object orbiting another object according to → Kepler's laws.→ Keplerian; → orbital; → velocity. Keplerian rotation curve   خم ِ چرخش ِ کپلری   xam-e carxeš-e Kepleri (#)Fr.: courbe de rotation keplérienne   A → rotation curve in which the speed of the orbiting body is inversely proportional to the → square root of its distance from the mass concentrated at the center of the system.→ Keplerian; → rotation; → curve. Keplerian shear   کرن ِ کپلری   karn-e KepleriFr.: cisaillement keplerien   Shearing motion of an ensemble of particles, each on a nearly circular, → Keplerian orbit. → Orbital velocity decreases as orbital radius increases, yielding shear. Viscous drag on such shear, due to ring-particle collisions, plays a key role in ring processes (Ellis et al., 2007, Planetary Ring Systems, Springer).→ Keplerian; → shear. Keplerian telescope   دوربین ِ کپلر، تلسکوپ ِ ~   durbin-e Kepler, teleskop-e ~ (#)Fr.: télescope de Kepler   A → refracting telescope which has simple → convex lenses for both → objective and → eyepiece. It suffers from → chromatic aberration, which can be reduced by increasing the → focal ratio. It was first devised by Kepler in 1615.→ Keplerian; → telescope.