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spectropolarimetry binâb-qotbešsanji Fr.: spectropolarimétrie A technique of observation in → astrophysics which combines → spectroscopy and → polarization measurements. Spectropolarimetry has a wide range of applications in astrophysics, including → stellar magnetic field studies. → ESPaDOnS, → HARPSpol. → spectro-; → polarimetry. |
spectroscope binâb-namâ (#) Fr.: spectroscope An optical instrument for forming and examining the spectrum of a light source. The instrument contains a narrow slit through which the light enters. The slit is placed at the focus of a positive lens called the collimator lens to form a beam of parallel rays. The beam of light falls on a dispersing element (prism, grating, or grism) which separates the light into its colors. This spectrum can be observed with an ocular (in the spectroscope) or recorded on a detector (in the spectrograph). |
spectroscopic binâbnemâyi, binâbnemaayik Fr.: spectroscopique Of or relating to → spectroscopy. |
spectroscopic binary dorin-e binâbnemâyi Fr.: binaire spectroscopique A binary system that cannot be resolved by a telescope, but can be identified by means of the Doppler shift of the spectral lines. As stars revolve, they alternately approach and recede in the line of sight. This motion is shown up in their spectra as a periodic oscillation or doubling of spectral lines. → spectroscopic; → binary. |
spectroscopic degeneracy vâgeni-ye binâbnemâyi Fr.: dégénérescence spectroscopique The situation in which spectroscopic features in a certain optical region are not sensitive enough to distinguish adjacent → luminosity classes, for instance → dwarf stars from → giant stars. → spectroscopic; → degeneracy. |
spectroscopic mass jerm binâbnemâyi Fr.: masse spectroscopique The stellar mass derived from → gravity (g) and radius (R), expressed by M = gR2/G, where G is the → gravitational constant. Spectroscopic mass conveys the actual mass of the star, in contrast with its → initial mass. → spectroscopic; → mass. |
spectroscopic parallax didgašt-e binâbnamâyi Fr.: parallaxe spectroscopique The measurement of a stellar distance by the absolute magnitude derived from the luminosity criteria of the spectrum and the apparent magnitude of the star. → spectroscopic; → parallax. |
spectroscopic variable vartande-ye binâbnemâyi Fr.: variable spectroscopique A → variable star that displays changes in its → spectrum. In such stars line intensities may vary and new lines may appear. Examples include → AG Carinae, HD 108, HD 191612, and HD 148937. → spectroscopic; → variable. |
spectroscopy binânnemâyi Fr.: spectroscopie The study of spectral lines from different atoms and molecules. Spectroscopy is an important part of studying the physical and chemical properties of astronomical objects. |
spectrum binâb (#) Fr.: spectre The → electromagnetic radiation divided into its constituting wavelengths or frequencies. From L. spectrum "appearance, image, apparition," from specere "to look at, view;" Gk. skopein "to behold, look, consider," skeptesthai "to look at;" PIE base *spek- "to see;" cf. Av. spas-, spaš- "to attend to; to serve; spy," spasiieiti "looks at, perceives" (Mod.Pers. sepâs "kindness, favor, thanksgiving," sepâsidan "to praise for benefits received);" Skt. paś- "to see, watch," spasati "sees;" L. specere "to look at;" O.H.G. spehônn "to spy," Ger. spähen "to spy." Binâb "a vision;" Mid.Pers. wênâb "vision," from wên-, present stem of didan "to see;" O.Pers. vain- "to see;" Av. vaēn- "to see;" cf. Skt. veda "I know;" Gk. oida "I know," idein "to see;" L. videre "to see;" PIE base *weid- "to know, to see." |
specular reflection bâztâb-e âyenevâr (#) Fr.: réflexion spéculaire The reflection of light waves in which the reflected waves travel in a definite direction, and the directions of the incident and reflected waves make equal angles with a line perpendicular to the reflecting surface. Same as → regular reflection; opposite of → diffuse reflection. From L. specularis, from speculum "mirror;" → reflection. Bâztâb, → reflection; âyenevâr "mirror-like," from âyené, → mirror + -vâr similarity suffix. |
speculate gâsidan Fr.: spéculer To guess possible answers to a question when there are not enough information to be certain. Back formation from O.Fr. speculation, from L. speculatus, p.p. of speculari "to watch over, observe," from specula "watch tower," from specere "to look at, regard," cognate with Av. spas- "to attend; to serve," spasiieiti "looks at, perceives;" Pers. sepâs "kindness, thanksgiving;" Skt. spasati "sees;" Gk. skopein "to behold, look, consider," skeptesthai "to look at;" O.H.G. spehhon "to spy;" Ger. spähen "to spy;" PIE *spek- "to look around, observe." Gâsidan infinitive from gâs, from Av. kas- "to look at, see," with extension of the vowel and change of the last phoneme from k to g, as in and cognate with negâh (Mid.Pers. nikâh), → look, âgâh (Mid.Pers. âkâh) "aware" (→ Space Situational Awareness), pargast "God forbid!," and maybe (Lori, Laki, Torbat-Heydarie-yi) gâs "perhaps," (Shirâzi, Fasâyi) gâsam "maybe;" cf. Skt. kāś- "to become visible, appear;" Gk. tekmor, tekmar "sign, mark;" PIE base *kwek- "to appear, show." |
speculation gâseš Fr.: spéculation The act or an instance of speculating. Verbal noun of → speculate. |
speech 1) soxan (#); 2) soxanrâni (#) Fr.: 1) parole; 2) discours, allocution 1) The faculty or power of speaking; oral communication; ability to
express one's thoughts and emotions by speech sounds and gesture (Dictionary.com). M.E. speche; O.E. spæc; cf. Dan. sprog, O.S. spraca, O.Fris. spreke, Du. spraak, O.H.G. sprahha, Ger. Sprache "speech." Soxan "speech, utterance, word;" Mid.Pers. saxwan "word, speech;" O.Pers. θanh- "to declare, say," aθaham "I said;" Av. səngh- "to declare," sənghāmi "I say;" cf. Skt. śams- "to praise, declare;" L. censere "to estimate, think; decide." |
speed tondi (#) Fr.: vitesse The ratio of the distance covered to the time taken by a moving body. Speed in a specified direction is → velocity. M.E. spede "good luck, prosperity, rapidity;" O.E. sped "success, prosperity, advancement;" cf. O.S. spod "success," Du. spoed "haste, speed," O.H.G. spuot "success," O.H.G. spuoten "to haste;" from PIE base *spe- "to thrive, prosper" (cf. Skt. sphā- "to increase, become fat;" L. sperare "to hope;" O.C.S. spechu "endeavor;" Lith. speju "to have leisure"). Tondi "speed," from tond "swift, rapid, brisk; fierce, severe" (Mid.Pers. tund "sharp, violent;" Sogdian tund "violent;" cf. Skt. tod- "to thrust, give a push," tudáti "he thrusts;" L. tundere "to thrust, to hit" (Fr. percer, E. pierce, ultimately from L. pertusus, from p.p. of pertundere "to thrust or bore through;" PIE base *(s)teud- "to thrust, to beat") + noun suffix -i. |
speed of light tondi-ye nur Fr.: vitesse de la lumière Same as → velocity of light. |
spend ziyâmidan Fr.: dépenser 1) To pay out, disburse, or expend; dispose of (money, wealth, resources, etc.). M.E. spenden, from O.En. -spendan (in forspendan "use up"), from M.L. spendere, from expendere "to pay out, weigh out money," from → ex- "out" + pendere "to pay, weigh." Ziyâmidan, from Sogd. zyâm "to consume, spend," ultimately from Proto-Ir. *uz-iam-, from *uz- "out, away," → ex-, + *iam- "to hold, take; stretch, reach out;" cf. Av. yam- "to hold, keep," (+ *apa-) "to take away;" Skt. yam- "to hold, restrain." |
sphere koré (#), sepehr (#) Fr.: sphère A solid geometric figure generated by the revolution of a semicircle about its diameter; equation: x2 + y2 + z2 = r2. M.E. spere, from O.Fr. espere, from L. sphæra "globe, ball, celestial sphere," from Gk. sphaira "globe, ball," of unknown origin. Koré, loan from Ar. kurat. |
sphere of influence sepehr-e hanâyeš Fr.: sphère d'influence The region of space around one of the bodies in a system of two celestial bodies where a third body of much smaller mass is influenced by the gravitational field of that body. The sphere of influence of a planet with respect to the Sun has a radius given by: R = RP(MP/MS)2/3, where RP is the radius of the planet's orbit around the Sun, MP is the mass of the planet, and MS is the solar mass. The sphere of influence of the Earth has a radius of about 927,000 km or slightly under 150 Earth radii. Beyond this limit, a space probe will come under the influence of the Sun. |
spheres of Eudoxus sepehrhâ-ye Eudoxus Fr.: sphères d'Eudoxe A series of spheres with varying radii centred on the Earth, each rotating uniformly about an axis fixed with respect to the surface of the next larger sphere, all comprising a model in Greek astronomy to describe the motions of the heavenly bodies. The spheres turned with different speeds about axes with different orientations. The fixed stars revolved around the Earth by the motion of the most distant sphere to which the stars were thought to be attached. Each of the five planets' (Mercury, Venus, Mars, Jupiter, and Saturn) motion could be described using four spheres. The Sun and the Moon required three spheres each to explain their motions. Therefore, a total of 27 spheres described the behavior of the heavenly bodies in terms of circular motion. Eudoxus was the first person to devise a model that could explain the → retrograde motion of the planets in the sky along a looped curve known as the → hippopede. → sphere; Eudoxus (Ευδοξοσ) of Cnidus (c 408 BC - c 355 BC), Greek astronomer and mathematician. |
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