# 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: 141 Search : system
 conservative system   راژمان ِ پتایش‌مند   râžmân-e patâyešmandFr.: système conservatif   A system in which there is no dissipation of energy so that the total energy remains unchanged with time. constrained system   راژمان ِ پاوندیده   râžmân-e pâvandidéFr.: système contraint   Opposite of a → free system. See also → constraint.Constrained, p.p. of → constrain; → system. coordinate system   راژمان ِ همارا   râžmân-e hamârâFr.: système de coordonnées   Math: A system for locating each point in space by a set of numbers. Astro: Values in a reference system used to relate the position of a body on the celestial sphere. Four main coordinate systems are utilized in astronomy: the equatorial, horizontal, ecliptic, and galactic coordinates systems.→ coordinate; → system. coupled systems   راژمان‌های ِ جفسر، ~ جفتیده   râžmânhâ-ye jafsar, ~ joftidéFr.: systèmes couplés   A set of two or more mechanical vibrating systems connected so that they interact with one another.→ coupled; → system; crystal system   راژمان ِ بلور، ~ بلوری   râžmân-e bolur, ~ boluriFr.: système cristallin   One of seven possible basic crystal types that is defined by the relations between the axis lengths and angles of its unit cell. Crystal systems can produce an infinite → lattice by successive translations in three-dimensional space so that each lattice point has an identical environment. The seven crystal systems are: → cubic, → orthorhombic, tetragonal, trigonal, hexagonal, monoclinic, and triclinic.→ crystal; → system. cubic crystal system   راژمان ِ بلوری ِ کابی   râžmân-e boluri-ye kâbiFr.: système cristallin cubique   A → crystal system whose three axes have equal lengths and all corners are 90°.→ cubic; → crystal; → system. de Vaucouleurs system   راژمان ِ دووکولور   râžmân-e de VaucouleursFr.: système de Vaucouleurs   A widely used scheme for classifying galaxies which is an extension to the → Hubble sequence Hubble sequence. De Vaucouleurs introduced a more elaborate classification system for spiral galaxies (→ spiral galaxy) based on three morphological characteristics: 1) Bars. Galaxies are divided on the basis of the presence or absence of a nuclear → stellar bar. SA denotes spiral galaxies without bars, complementing Hubble's use of SB for → barred spirals. De Vaucouleurs also defined an intermediate class, SAB, containing weakly barred spirals. → Lenticular galaxies are also classified as unbarred (SA0) or barred (SB0), with the notation S0 reserved for those galaxies for which it is impossible to tell if a bar is present or not. 2) Rings. Galaxies possessing ring-like structures are denoted (r), those without rings (s), and transition galaxies (rs). 3) Spiral arms. These are divided into the following subclasses: Sd (SBd), that is diffuse, broken arms made up of individual stellar clusters and nebulae; very faint central → bulge; Sm (SBm): irregular in appearance; no bulge component; and Im, that is highly irregular galaxy. Galaxies in the classes Sm and Im are termed the → Magellanic spirals and irregulars, respectively. The → Large Magellanic Cloud is of type SBm, while the → Small Magellanic Cloud is an irregular (Im). decimal number system   راژمان ِ عددهای ِ دهدهی   râžmân-e adadhâ-ye dahdahiFr.: système des nombres décimaux   A system of numerals for representing real numbers that uses the → base 10. It includes the digits from 0 through 9.→ decimal; → system. decimal system   راژمان ِ دهدهی   râžmân-e dahdahiFr.: système décimal   same as → decimal number system.→ decimal; → number; → system. detached system   راژمان ِ جدا   râžmân-e jodâFr.: système détaché   A binary system whose components are not in contact and in which no significant mass exchange is occurring.P.p. of detach, from O.Fr. destachier (Fr. détacher), from des- "apart," + -tachier (as in atachier "to attach"); → system.Râžmân→ system; jodâ "separate, distinct," Mid.Pers. jutâk (yutâk), jut (yut). differentially rotating system   راژمان ِ دگرسانه چرخان   râžmân-e degarsâné carxânFr.: système en rotation différentielle   A system characterized by → differential rotation. In such a system the → angular velocity decreases as the distance from the rotation center increases.→ differential; → rotating; → system. dissipative system   راژمان ِ افتالی   râžmân-e eftâliFr.: système dissipatif   A → dynamical system which undergoes energy → dissipation. Such a system gives rise to → irreversible processes, associated with a time-asymmetric evolution of observable quantities.→ dissipative; → system. double-degenerate binary system   راژمان ِ درین ِ دوبار واگن   râžmân-e dorin-e dobâr vâgenFr.: système binaire doublement dégénéré   A system of evolved → binary stars in which both → components have ejected their envelopes and evolve toward → white dwarf stage. So far a half dozen double-degenerate → binary systems are known, for example Henize 2-248 (M. Santander-Garcia et al., 2015, 518, 5).→ double; → degenerate; → binary; → system. dynamical system   راژمان ِ توانیک   râžmân-e tavânikFr.: système dynamique   A system composed of one or more entities in which one state develops into another state over the course of time.→ dynamical; → system. early solar system   راژمان ِ خورشیدی ِ آغازین   râžmân-e xoršidi-ye âqâzinFr.: système solaire primordial   A period in the evolution of the → solar system when the planets and satellites were in the process of formation.→ early; → solar; → system. Earth-Moon system   راژمان ِ زمین-ماه   râžmân-e Zamin-MâhFr.: système Terre-Lune   A physical system composed on the → Earth and the → Moon in which both objects directly influence each other. The total energy in the Earth-Moon system is conserved. The most notable influence that the two objects have on each other is → tides. See also: → tidal braking, → tidal bulge, → tidal capture, → tidal coupling, → tidal disruption, → tidal force, → tidal friction, → tidal heating, → tidal locking, → tidal radius, → tidal stretching.→ Earth; → Moon; → system. ecliptic system   راژمان ِ هورپهی   râžmân-e hurpehiFr.: système écliptique   Coordinate system with the ecliptic as the fundamental plane.→ ecliptic; → system. ecosystem   بوم راژمان   bumrâžmânFr.: écosystème   Any geographic area that includes all of the organisms and nonliving parts of their physical environment.→ ecology; → system. equator system   راژمان ِ هموگاری   râžmân-e hamugâriFr.: système équatorial   A set of celestial coordinates based on the celestial equator as the primary great circle. The coordinates are → declination and → right ascension.→ equator; → system. equatorial coordinate system   راژمان ِ هماراهای ِ هموگاری   râžmân-e hamârâhâ-ye hamugâriFr.: système de coordonnées équatoriales   An astronomical → coordinate system for indicating the positions of → celestial objects on the → celestial sphere. The system consists of two components, → right ascension and → declination. Right ascension is the angle between the → vernal equinox and the point where the → hour circle intersects the → celestial equator. The right ascension is always measured eastward from the vernal equinox, in the units of hours, minutes, and seconds. Declination is the angle between the celestial equator and the position of the star measured along the star's hour circle. It is measured in degrees, minutes, and seconds north or south of the celestial equator. By definition, the vernal equinox is located at right ascension 0h and declination 0°. Equatorial coordinates change with time due to the → precession of the Earth's → rotation axis.→ equatorial; → coordinate; → system.