# 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: 50 Search : rotation
 projected rotational velocity   تندای چرخشی ِ فراشانده   tondâ-ye carxeši-ye farâšândéFr.: vitesse rotationnelle projetée   The → angular velocity of a star deduced from the → rotational broadening of its → spectral lines. It is expressed as v sini, where i is the → inclination of the rotational axis with respect to the normal to the → plane of the sky. The real equatorial rotational velocity can be determined only if the inclination of the rotational axis is known.Projected, p.p. of → project; → rotational; → velocity. rotation   چرخش   carxeš (#)Fr.: rotation   The motion of a body about its axis.Verbal noun of → rotate. rotation axis   آسه‌ی ِ چرخش   âse-ye carxešFr.: axe de rotation   The imaginary line around which an object rotates. Same as → rotational axis and → axis of rotation.→ rotation; → axis. rotation curve   خم ِ چرخش   xam-e carxešFr.: courbe de rotation   A plot of the variation in → orbital velocity of stars and → interstellar matter with distance from the center of a → galaxy. A "flat" rotation curve indicates that the mass of the galaxy increases linearly with distance from its center. See also: farsi→ Keplerian rotation curveRotation; → curve. rotation energy   کاروژ ِ چرخش   kâruž-e carxešFr.: énergie de rotation   The → kinetic energy of rotational motion of an object. It is expressed by ER = (1/2)Iω2, where I is the → moment of inertia and ω → angular velocity (2π/P).→ rotation; → energy. rotation frequency   بسامد ِ چرخش   basâmad-e carxešFr.: fréquence de rotation   1) The number of rotations per unit time of a rotating object. 2) The number of → stellar rotations per unit time. The reciprocal of the → rotation period. This parameter usually refers to the equator of the star, because stars do not rotate as solid bodies.→ rotation; → frequency. rotation period   دوره‌ی ِ چرخش   dowre-ye carxeš (#)Fr.: période de rotation   The interval of time during which an object turns once about its axis.→ rotation; → period. rotation phase   فاز ِ چرخش   fâz-e carxešFr.: phase de rotation   A position parameter used in → stellar magnetic field studies. Its zero value represents the moment when, during → stellar rotation, the positive → magnetic pole is nearest to the → line of sight.→ rotation; → phase. rotation-induced turbulence   آشوبناکی ِ زاییده‌ی ِ چرخش، ~ درهازیده از ~   âšubnâki-ye zâyide-ye carxeš, darhâzidé az ~Fr.: turbulence induite par turbulence   A type of → turbulence with motions more vigorous in the horizontal than in the vertical direction occurring in internal radiation zone of → rotating stars. Same as → shear turbulence.→ rotation; → induced; → turbulence. rotation-powered pulsar (RPP)   تپار ِ چرخش-توان، پولسار ِ ~ ~   tapâr-e carxeš-tavân, pulsâr-e ~ ~Fr.:   A → neutron star that is spinning down as a result of → torques from → magnetic dipole radiation and particle emission. RPPs derive their energy primarily from the → rotation of the neutron star. The energy from their → spin-down appears as broad-band pulsations from → radio to → gamma-ray wavelengths and as a → wind of energetic particles flowing into their surrounding → pulsar wind nebulae. Since the discovery of RPPs through their radio → pulsations in 1967, more than 2000 → radio pulsars are now known with periods ranging from a few milliseconds to several seconds (A. K. Harding, 2013, Front. Phys. 8, 679).→ rotation; → power; → pulsar. rotation-vibration spectrum   بیناب ِ چرخش-شیوش   binâb-e carxeš-šivešFr.: spectre rotation-vibration   The spectrum of a molecule resulting from the simultaneous rotation and vibration of its constituent atoms.→ rotation; → vibration; → spectrum. rotational   چرخشی   carxeši (#)Fr.: rotationnel   Of or pertaining to → rotation.Rotational, adj., from → rotation + → -al. rotational angular momentum   جنباک ِ زاویه‌ای ِ چرخشی   jonbâk-e zâviyeyi-ye carxešiFr.: moment angulaire rotationnel, moment cinétique ~   The → angular momentum of a body rotating about an axis. The rotational angular momentum of a solid homogeneous sphere of mass M and radius R rotating about an axis passing through its center with a period of T is given by: L = 4πMR2/5T.→ rotational; → angular; → momentum. rotational axis   آسه‌ی ِ چرخش   âse-ye carxešFr.: axe de rotation   An imaginary line about which a solid object rotates. Same as → rotation axis and → axis of rotation.→ rotational; → axis. rotational broadening   پهنش ِ چرخشی   pahneš-e carxešiFr.: élargissement rotationnel   The spectral line broadening caused by stellar rotation. Light from two rims of the star will be Doppler shifted in opposite directions, resulting in a line broadening effect. The line broadening depends on the inclination of the star's pole to the line of sight. The derived value is a function of ve. sini, where ve is the rotational velocity at the equator and i is the inclination, which is not always known. The fractional width (Δλ/λ) is of the order of 10-3 for B stars.→ rotational; → broadening. rotational Eddington limit   حد ِ ادینگتون ِ چرخشی   hadd-e Eddington-e carxešiFr.: limite d'Eddington avec rotation   The → Eddington limit of luminosity for a → rotating star in which both the effects of → radiative acceleration and rotation are important. Such objects mainly include → OB stars, → LBV, → supergiants, and → Wolf-Rayet stars. It turns out that the maximum permitted luminosity of a star is reduced by rotation, with respect to the usual Eddington limit (Maeder & Meynet, 2000, A&A, 361, 159). rotational energy   کاروژ ِ چرخشی   kâruš-e carxešiFr.: énergie rotationnelle   The → kinetic energy due to the → rotation of and object. Rotational energy is part of the total kinetic energy of the body. It is given by: (1/2)Iω2, where I is the → moment of inertia and ω is the → angular velocity. Same as → angular kinetic energy.→ rotational; → energy. rotational mixing   آمیزش ِ چرخشی   âmizeš-e carxešiFr.: mélange rotationnel   A consequence of → stellar rotation that deforms the star, triggers instabilities (→ shear turbulence and → meridional currents) leading to → transport of chemical species in the star. The efficiency of rotational mixing (measured for instance by the degree of surface → enrichments at a given → evolutionary stage) increases when the initial mass and rotation increase. This efficiency increases also when the initial → metallicity decreases. This is due to the fact that when the metallicity is lower, the stars are more compact. This makes the → gradients of the → angular velocity steeper in the stellar interiors. Steeper gradients produce stronger shear turbulence and thus more mixing. Rotational mixing can bring to the surface heavy elements newly synthesized in the stellar core. Rotation thus produces an increase of the → opacity of the outer layers and activates strong → mass loss through → radiatively driven winds. This effect may be responsible for the loss of large fractions of the initial mass of the star (Meynet et al. 2007, arXiv:0709.2275).→ rotational; → mixing. rotational modulation (ROT)   دگر‌آهنگش ِ چرخشی   degarâhangeš-e carxešiFr.: modulation rotationnelle   A very small variation in the surface brightness of a single star due to its rotation. Several types of stars are known to have photospheric spots. Brightness variation occurs as rotation carries star spots or other localized activity across the line of sight.→ rotational; → modulation. rotational motion   جنبش ِ چرخشی   jonbeš-e charkheshiFr.: mouvement de rotation   Of a → rigid body, a motion in which there are always two points of the body which remain motionless.→ rotational; → motion.

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