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conservative system râžmân-e patâyešmand Fr.: système conservatif A system in which there is no dissipation of energy so that the total energy remains unchanged with time. → conservative→ system. |
constrained system râžmân-e pâvandidé Fr.: système contraint Opposite of a → free system. See also → constraint. |
coordinate system râžmân-e hamârâ Fr.: système de coordonnées Math: A system for locating each point in space by a set of numbers. → coordinate; → system. |
coupled systems râžmânhâ-ye jafsar, ~ joftidé Fr.: systèmes couplés A set of two or more mechanical vibrating systems connected so that they interact with one another. |
crystal system râžmân-e bolur, ~ boluri Fr.: 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. |
cubic crystal system râžmân-e boluri-ye kâbi Fr.: système cristallin cubique A → crystal system whose three axes have equal lengths and all corners are 90°. |
de Vaucouleurs system râžmân-e de Vaucouleurs Fr.: 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: → de Vaucouleurs radius; → system. |
decimal number system râžmân-e adadhâ-ye dahdahi Fr.: 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 râžmân-e dahdahi Fr.: système décimal same as → decimal number system. |
detached system râžmân-e jodâ Fr.: 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 râžmân-e degarsâné carxân Fr.: 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 râžmân-e eftâli Fr.: 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 râžmân-e dorin-e dobâr vâgen Fr.: 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 râžmân-e tavânik Fr.: système dynamique A system composed of one or more entities in which one state develops into another state over the course of time. |
early solar system râžmân-e xoršidi-ye âqâzin Fr.: système solaire primordial A period in the evolution of the → solar system when the planets and satellites were in the process of formation. |
Earth-Moon system râžmân-e Zamin-Mâh Fr.: 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. |
ecliptic system râžmân-e hurpehi Fr.: système écliptique Coordinate system with the ecliptic as the fundamental plane. |
ecosystem bumrâžmân Fr.: écosystème Any geographic area that includes all of the organisms and nonliving parts of their physical environment. |
equator system râžmân-e hamugâri Fr.: système équatorial A set of celestial coordinates based on the celestial equator as the primary great circle. The coordinates are → declination and → right ascension. |
equatorial coordinate system râžmân-e hamârâhâ-ye hamugâri Fr.: 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. |
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