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: 509
 least common multiplier (LCM)   کوچکترین بستاگر ِ همدار   kucektarin bastâgar-e hamdârFr.: plus petit commun multiple   Of two or more → integers, the smallest positive number that is divisible by those integers without a remainder.→ least; → common; → multiplier. least squares   کوچکترین چاروش‌ها   kucaktarin cârušhâFr.: moindres carrés   Any statistical procedure that involves minimizing the sum of squared differences.→ least; → square. least-squares deconvolution (LSD)   واهماگیش ِ کمترین چاروشها   vâhamâgiš-e kucaktarin cârušhâFr.: déconvolution des moindres carrés   A → cross correlation technique for computing average profiles from thousands of → spectral lines simultaneously. The technique, first introduced by Donati et al. (1997, MNRAS 291,658), is based on several assumptions: additive → line profiles, wavelength independent → limb darkening, self-similar local profile shape, and weak → magnetic fields. Thus, unpolarized/polarized stellar spectra can indeed be seen as a line pattern → convolved with an average line profile. In this context, extracting this average line profile amounts to a linear → deconvolution problem. The method treats it as a matrix problem and look for the → least squares solution. In practice, LSD is very similar to most other cross-correlation techniques, though slightly more sophisticated in the sense that it cleans the cross-correlation profile from the autocorrelation profile of the line pattern. The technique is used to investigate the physical processes that take place in stellar atmospheres and that affect all spectral line profiles in a similar way. This includes the study of line profile variations (LPV) caused by orbital motion of the star and/or stellar surface inhomogeneities, for example. However, its widest application nowadays is the detection of weak magnetic fields in stars over the entire → H-R diagram based on → Stokes parameter V (→ circular polarization) observations (see also Tkachenko et al., 2013, A&A 560, A37 and references therein).→ least; → square; → deconvolution. least-squares fit   سز ِ کوچکترین چاروش‌ها   saz-e kucaktarin cârušhâFr.: ajustement moindres carrées   A fit through data points using least squares.→ least squares; → fit. leave   ۱) پریژیدن؛ ۲) پریژ   1) parižidan; 2) parižFr.: 1) quitter; 2) congé, permission   1a) Go away from. 1b) To let remain or have remaining behind after going, disappearing, ceasing, etc. 2a) Permission to be absent, as from work or military duty. 2b) The time this permission lasts (Dictionary.com).M.E. leven, from O.E. laefan "to allow to remain in the same state or condition" (cf. O.Saxon farlebid "left over;" Ger. bleiben "to remain") ultimately from PIE *leip- "to stick, adhere;" also "fat," from which the cognates: Gk. lipos "fat;" O.E. lifer "liver," → life.Parižidan, on the model of Sariqoli barēzj "leavings;" Yaghnobi piraxs- "to stay behind, remain;" ultimately from Proto-Ir. *apa-raic-, from *raic- "to abandon, leave;" cf. Av. raēc- "to leave, let" (Cheung 2006), → heritage. Leavitt law   قانون ِ لویت   qânun-e LeavittFr.: loi de Leavitt   Same as the → period-luminosity relation.Named after Henrietta Swan Leavitt (1868-1921), American woman astronomer, who discovered the relation between the luminosity and the period of → Cepheid variables (1912); → law. Leclanché cell   پیل ِ لوکلانشه   pil-e Leclanché (#)Fr.: pile de Leclanché   A → primary cell in which the anode is a rod of carbon and the cathode a zinc rod both immersed in an electrolyte of ammonia plus a depolarizer.Named after the inventor Georges Leclanché (1839-1882), a French chemist, → cell. Leda   لدا   Ledâ (#)Fr.: Léda   1) The ninth of Jupiter's known satellites and the smallest. It is 16 km in diameter and has its orbit at 11 million km from its planet. Also called Jupiter XIII, it was discovered by Charles Kowal (1940-), an American astronomer, in 1974. 2) An asteroid, 38 Leda, discovered by J. Chacornac in 1856.In Gk. mythology, Leda was queen of Sparta and the mother, by Zeus in the form of a swan, of Pollux and Helen of Troy. Ledoux's criterion   سنجیدار ِ لو‌دو   sanjidâr-e LedouxFr.: critère de Ledoux   An improvement of → Schwarzschild's criterion for convective instability, which includes effects of chemical composition of the gas. In the Ledoux criterion the gradient due to different molecular weights is added to the adiabatic temperature gradient.After the Belgian astrophysicist Paul Ledoux (1914-1988), who studied problems of stellar stability and variable stars. He was awarded the Eddington Medal of the Royal Astronomical Society in 1972 (Ledoux et al. 1961 ApJ 133, 184); → criterion. left   چپ   cap (#)Fr.: gauche   Of, pertaining to, or located on or toward the west when somebody or something is facing north. Opposite of → right.M.E. left, lift, luft, O.E. left, lyft- "weak, idle," cf. Ger. link, Du. linker "left," from O.H.G. slinc, M.Du. slink "left," Swed. linka "limp," slinka "dangle."Cap "left," from unknown origin. left-hand rule   رزن ِ دست ِ چپ   razan-e dast-e capFr.: règle de la main gauche   See → Fleming's rules.→ left; → hand; → rule. left-handed   چپال، چپدست   capâl (#) , capdast (#)Fr.: gaucher   Using the left hand with greater ease than the right.→ left; → hand + -ed.Capâl, from cap, → left, + -al, → -al. Capdast, with dast, → hand. leg   ۱) لنگ؛ ۲) ساق   1) leng (#); 2) sâq (#)Fr.: jambe   1) The part of the body from the top of the → thigh down to the → foot. 2) Anatomy: The lower limb of a human being between the → knee and the → ankle.M.E., from O.Norse leggr; cognate with Dan. læg, Swed. läg "the calf of the leg."Leng, related to Mid.Pers. zang "shank, ankle;" Av. zanga-, zənga- "bone of the leg; ankle bone; ankle;" Skt. jánghā- "lower leg;" maybe somehow related to E. → shank. legal   قانونی   qânuni (#)Fr.: légal   1) Permitted by law; lawful. 2) Of or relating to law; connected with the law or its administration (Dictionary.com).From M.Fr. légal or directly from L. legalis "legal, pertaining to the law," from lex (genitive legis) "law."Qânuni, of or relating to qânun, → law. legend   چیروک   cirokFr.: légende   1) A non-historical or unverifiable story handed down by tradition from earlier times and popularly accepted as historical. 2) The body of stories of this kind, especially as they relate to a particular people, group, or clan (Dictionary.com).M.E. legende "written account of a saint's life," from O.Fr. legende and directly from M.L. legenda literally, "(things) to be read," noun use of feminine of L. legendus, gerund of legere "to read" (on certain days in church).Cirok, from Kurd. cirok "story, fable," related to Kurd. cir-, cirin "to sing, [to recite?];" Av. kar- "to celebrate, praise;" Proto-Ir. *karH- "to praise, celebrate;" cf. Skt. kar- "to celebrate, praise;" O.Norse herma "report;" O.Prussian kirdit "to hear;" PIE *kerH2- "to celebrate" (Cheung 2007). legendary   چیروکی   cirokiFr.: légendaire   Of, relating to, or of the nature of a legend.→ legend; → -ary. Legendre equation   هموگش ِ لوژاندر   hamugeš-e LegendreFr.: équation de Legendre   The → differential equation of the form: d/dx(1 - x2)dy/dx) + n(n + 1)y = 0. The general solution of the Legendre equation is given by y = c1Pn(x) + c2Qn(x), where Pn(x) are Legendre polynomials and Qn(x) are called Legendre functions of the second kind.Named after Adrien-Marie Legendre (1752-1833), a French mathematician who made important contributions to statistics, number theory, abstract algebra, and mathematical analysis; → equation. Legendre transformation   ترادیسش ِ لوژاندر   tarâdiseš-e LegendreFr.: transformation de Legendre   A mathematical operation that transforms one function into another. Two differentiable functions f and g are said to be Legendre transforms of each other if their first derivatives are inverse functions of each other: df(x)/dx = (dg(x)/dx)-1. The functions f and g are said to be related by a Legendre transformation. legislation   قانونگذاری   gânungozâri (#)Fr.: législation   1) The act of making or enacting laws. 2) A law or a body of laws enacted (Dictionary.com).From Fr. législation, from L.L. legislationem, from legis latio, "proposing (literally 'bearing') of a law," → legislator.Qânungoz&acric;ri "act or process followed by the qânungoz&acric;r", → legislator. legislator   قانونگذار   qânungozâr (#)Fr.: législateur   1) A person who gives or makes laws. 2) A member of a legislative body (Dictionary.com).From L. legis lator "proposer of a law," from legis, genitive of lex, → law, + lator "proposer," agent noun of latus "borne, brought, carried."Qânungozâr, literally "he who places the law," from qânun, → law, + gozâr, present stem and agent noun of gozâštan "to place, put; perform; allow, permit," related to gozaštan "to pass, to cross," → trans-