# 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: 5 Search : centrifugal
 centrifugal   مرکزگریز   markaz-goriz (#)Fr.: centrifuge   Acting or moving in a direction away from the axis of rotation or the center of a circle along which a body is moving.From Mod.L., coined 1687 by Sir Isaac Newton from L. centri-, combining form of centrum, → center, + fugere "to run away, flee."Markaz-goriz, from markaz, → center, + goriz "running away," from gorixtan, gorizidan "to run away," Mid.Pers. virextan, proto-Iranian *vi-raik, from vi- "apart, asunder" + *raik, Av. raek- "to leave, set free, let off," Mid./Mod.Pers. reg/rig (in mordé-rig "inheritance," Skt. ric- "to leave," rinakti "gives up, evacuates," Gk. leipein "to leave," L. linquere "to leave," from PIE *linkw-, from *leikw- "to leave behind" (cf. Goth. leihvan, O.E. lænan "to lend;" O.H.G. lihan "to borrow;" O.N. lan "loan"). centrifugal acceleration   شتاب ِ مرکزگریز   šetâb-e markaz-goriz (#)Fr.: accélération centrifuge   Of a point rotating in a circle round a central point, the outward acceleration away from the rotation axis. It corresponds to → centrifugal force. The centrifugal acceleration is given by ω x ω x r, or v2/r, where ω is → angular velocity, r the distance to the rotating axis, and v the → tangential velocity. The centrifugal and → centripetal accelerations are equal and opposite. centrifugal force   نیروی ِ مرکزگریز   niru-ye markaz-goriz (#)Fr.: force centrifuge   A force in a rotating reference frame directed outward from the axis of rotation.→ centrifugal; → force. magnetocentrifugal acceleration   شتاب ِ مغنات-مرکزگریز   šetâb-e meqnât-markazgorizFr.: accelération magnetocentrifuge   The acceleration exerted on the plasma particles according to the → magnetocentrifugal model. magnetocentrifugal model   مدل ِ مغنات-مرکزگریز   model-e meqnât-markazgorizFr.: modèle magnétocentrifuge   A → magnetohydrodynamic model devised to account for the → bipolar jets and → outflows observed around → protostars. Basically, a → poloidal magnetic field is frozen into a rotating → accretion disk. If the angle between the magnetic field lines threading the disk and the rotation axis of the disk is larger than 30°, the plasma can be accelerated out of the accretion disk along the field lines. The field lines rotate at a constant → angular velocity, and as the gas moves outward along the field lines, it is accelerated by an increasing → centrifugal force (magnetocentrifugal acceleration). At some point, when the rotation velocity is about the same as the → Alfven velocity in the gas, the field lines get increasingly wound up by the inertia of the attached gas and a strong → toroidal magnetic field component is generated. The toroidal component is the main agent in collimating the flow into a direction along the → open magnetic field lines. The earliest version of the model was proposed by Blandford & Payne (1982, MNRAS 199, 883). It has two main versions: → X-wind and → disk wind models. See also → magnetorotational instability.→ magneto-; → centrifugal; → model.