# 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: 316 Search : act
 scale factor   کروند ِ مرپل   karvand-e marpelFr.: facteur d'échelle   Math.: A number which scales, or multiplies, some quantity. In the equation y = Cx, C is the scale factor for x. C is also the coefficient of x, and may be called the constant of proportionality of y to x. Geometry: The ratio of any two corresponding lengths in two similar geometric figures. The ratio of areas of two similar figures is the square of the scale factor.→ scale; → factor. scientific fact   باشای ِ دانشی، ~ دانشیک   bâšâ-ye dâneši, ~ dânešikFr.: fait scientifique   An agreement by competent observers of a series of observations of the same phenomena. From time to time scientific facts are revised by additional data (G. Smooth, Lawrence Berkeley Lab website).→ scientific; → fact. screened Coulomb interaction   اندرژیرش ِ باپرده‌ی ِ کولن   andaržireš-e bâparde-ye CoulombFr.: interaction de Coulomb écrantée   The → Coulomb interaction reduced owing to the presence of other electrons. See → shielding effect.→ screen; → coulomb; → interaction. second contact   پرماس ِ دوم   parmâs-e dovomFr.: deuxième contact   The beginning of the total phase of a solar eclipse when the leading edge of the Moon touches the eastern edge of the Sun completely obscuring the Sun.→ second; → contact. simple fraction   برخه‌ی ِ ساده   barxe-ye sâdéFr.: fraction simple   A fraction in which the → numerator and → denominator are positive → integer numbers. Compare → compound fraction.→ simple; → fraction. sky subtraction   زیرکرشش ِ آسمان   zirkaršeš-e âsmânFr.: soustraction de ciel   The act or instance of removing the contribution of non-related, intervening foreground light to the object.→ sky; → subtraction. solar activity   ژیرندگی ِ خورشید   žirandegi-ye xoršidFr.: activité solaire   The general term for all forms of short-lived phenomena on the Sun, including → solar flares, → sunspots, → prominences, etc., indicating that the Sun is an active star.→ solar; → activity. solar activity cycle   چرخه‌ی ِ ژیرندگی ِ خورشید   carxe-ye žirandegi-ye xoršidFr.: cycle d'activité solaire   Same as the → solar cycle.→ solar activity; → cycle. Stokes friction factor   کروند ِ مالش ِ استوکس   karvand-e mâleš-e StokesFr.: facteur de friction de Stokes   For the translational motion of a spherical body moving in a → viscous fluid, the proportionality factor between the uniform flow velocity far from the sphere and the drag force, provided no-slip boundary condition and small → Reynolds numbers: f = 6πηR, where η is the Reynolds number and R radius of the sphere.→ Stokes; → friction; → factor. strong interaction   اندرژیرش ِ سترگ   andaržireš-e sotorgFr.: interaction forte   The interaction between quarks that is transmitted by gluons. The characteristic range of the strong interaction is 10-13 cm, and the time scale over which it operates is on the order of 10-23 second. Also called → strong force.→ strong; → interaction. subcritical reactor   واژیرگر ِ زیر-پرژنی   vâžirgar-e zir-paržaniFr.: réacteur sous-critique   A → nuclear reactor in which the rate of production of → fission neutrons is lower than the rate of production in the previous generation, and therefore the number of fissions decreases over time.→ subcritical; → reactor. subtract   زیرکرشیدن، کاهیدن   zirkaršidan, kâhidanFr.: soustraire   To take one number away from another; deduct. To perform the arithmetic operation of → subtraction.From L. subtractus, p.p. of subtrahere "to draw from beneath, take away, draw off," from → sub- "from under" + trahere "to pull, draw."Zirkaršidan, literally "to draw beneath," from zir-, → sub-, + karšidan "to draw, pul, drag," variant of kašidan "to draw, protract, trail, drag, carry;" Av. karš- "to draw; to plow," karša- "furrow;" Proto-Iranian *kerš-/*xrah- "to draw, plow;" cf. Skt. kars-, kársati "to pull, drag, plow;" Gk. pelo, pelomai "to move, to bustle;" PIE base kwels- "to plow." Kâhidan, → decrease. subtraction   زیرکرشش   zirkaršešFr.: soustraction   The operation of finding the difference between two numbers or quantities.Verbal noun of → subtract. subtractive   زیرکرششی   zirkaršešiFr.: soustractif   1) Constituting or involving → subtraction. 2) Math.: Indicating or requiring subtraction; having a → minus sign.→ subtract; → -ive. subtractive color   رنگ ِ زیرکرششی   rang-e zirkaršešiFr.: synthèse soustractive   Color produced by mixing pigments rather than light. Mixing all of the subtractive colors together results in the color black. See also → additive color.→ subtractive; → color. supergalactic   ابرکهکشانی   abarkahkašâniFr.: supergalactique   Of or pertaining to a system composed of nearby groups and clusters of galaxies in the → local Universe. Se also → galaxy cluster.→ super-; → galactic. supergalactic coordinate system   راژمان ِ هماراهای ابرکهکشانی   râžmân-e hamârâhâ-ye abarkahkašâniFr.: système des coordonnées supergalactiques   A spherical → coordinate system in which the → equator is the → supergalactic plane. Supergalactic longitude, SGL, is measured → counterclockwise from direction l = 137.37 deg, b = 0 deg (between 0 and 360 deg). The zero point for supergalactic longitude is defined by the intersection of this plane with the → Galactic plane. In the → equatorial coordinate system (J2000) this is approximately 2.82 h, +59.5 deg. Supergalactic latitude, SGB, is measured from the supergalactic plane, positive northward and negative southward. The North Supergalactic Pole (SGB=90 deg) lies at galactic coordinates l = 47.37 deg, b = +6.32 degrees, corresponding to the equatorial coordinate system (J2000) 18.9 h, +15.7 deg.→ supergalactic; → coordinate; → system. supergalactic latitude   ورونای ِ ابرکهکشانی   varunâ-ye abarkahkašâniFr.: latitude supergalactique supergalactic longitude   درژنای ِ ابرکهکشانی   derežnâ-ye abarkahkašâniFr.: longitude supergalactique supergalactic plane   هامن ِ ابرکهکشانی   hâmon-e abarkahkašâniFr.: plan supergalactique   The symmetry plane of the → Local Supercluster, where density of galaxies in our environment is the largest. The plane passes through the → Virgo cluster of galaxies, about which many of the brightest galaxies in the sky are concentrated. The supergalactic plane was recognized by Gérard de Vaucouleurs (1918-1995) in 1953 from the  → Shapley-Ames catalogue.→ supergalactic; → plane.