An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 12937 Search : far
first
  نخست، نخستین، یکم، آغاز   
naxost (#), naxostin (#), yekom (#), âqâz (#)

Fr.: premier   

Being before all others with respect to time, order, importance, etc., used as the ordinal number of one.

O.E. fyrst "foremost," superlative of fore, from P.Gmc. *furisto (cf. O.H.G. furist, O.N. fyrstr, Dan. første, M.Du. vorste "first," Ger. Fürst "prince"), superlative of *fur-/*for-, from PIE *pro- (cf. Av. pouruua- "first," fra- "forward, forth;" Skt. pūrva- "first," pra- "before, formerly," Gk. pro; L. pro; E. fore).

Naxost, from Mid.Pers. naxust "the first," Parthian Mid.Pers. nxwšt, from naxu, Manichean Parthian nwx "beginning" + -ist superlative suffix, Av. -išta-, cf. Skt. -istha-, Gk. -istos, O.H.G. -isto, -osto, O.E. -st, -est, -ost; naxostin, from naxost + suffix -in.
Yekom, from yek, → one, + -om suffix of ordinal numbers.
Âqâz "beginning," from Proto-Iranian *āgāza-, from prefix ā- + *gāz- "to take, receive," cf. Sogdian āγāz "beginning, start," pcγz "reception, taking."

first approximation
  نزدین ِ نخست   
nazdin-e naxost

Fr.: première approximation   

1) Generally, an expression to indicate that a comment or result is only approximate.
2) Math.: In calculus, limiting a differential equation to its → first derivative, for example: ex≅ 1 + x. Also called → linear approximation.

first; → approximation.

first collapse
  رمبش ِ نخست   
rombeš-e naxost

Fr.: premier effondrement   

An early phase in the process of star formation which begins when the mass of a → molecular cloud → clump exceeds the → Jeans mass. The collapse is initially → optically thin to the thermal emission from → dust grains, and the compressional heating rate is much smaller than the cooling rate by the → thermal radiation. The collapse proceeds → isothermally. The isothermal condition is broken when the central density reaches about 10-13 g cm-3 and a small region at the center of the cloud starts to become → opaque. The heat generated by the collapse in this region is no longer freely radiated away, and the compression becomes approximately → adiabatic. The central temperature and pressure then begin to rise rapidly, soon becoming sufficient to decelerate and stop the collapse at the center. There then arises a small central core, called the → first core, in which the material has stopped collapsing and is approaching → hydrostatic equilibrium. Outside this core, the material is still nearly isothermal and continues to fall inward almost in → free fall. Consequently a shock front arises at the boundary of the core, where the infalling material is suddenly stopped. The initial mass and radius of the core are about 1031 g and 6 x 1013 cm, respectively, and the central density and temperature are about 2 x 10-10 g cm-3 and 170 K, respectively. As the collapse proceeds, the core grows in mass due to the infall of the surrounding material; at the same time, however, the core radius decreases because of radiative energy losses from the outer layers of the core. The process leads to the → second collapse (R. B. Larson, 1969, MNRAS 145, 271).

first; → collapse.

first contact
  پرماس ِ نخست   
parmâs-e naxost

Fr.: premier contact   

1) The beginning of a → solar eclipse when the eastern part of the lunar limb touches the western limb of the Sun, marking the beginning of an eclipse.
2) For a → lunar eclipse, the moment when the eastern limb of the Moon is the first to enter the Earth's shadow.

first; → contact.

first core
  مغزه‌ی ِ نخست   
maqze-ye naxost

Fr.: premier cœur   

A first object in → hydrostatic equilibrium predicted to form during early dynamical contraction of a → molecular cloud → clump in the course of the → first collapse.

first; → core.

first degree equation
  هموگش ِ درجه‌ی ِ یکم   
hamugeš-e daraje-ye yekom

Fr.: équiation du premier degré   

A equation in which the highest → exponent of the → variable is 1. Same as → linear equation.

first; → degree; → equation.

first derivative
  واخنه‌ی ِ نخست   
vâxane-ye naxost

Fr.: dérivée première   

The simplest mathematical → differentiation of one quantity relative to another; df(x)/dx. It is the same as → derivative, contrasted with the → second derivative or the nth derivative.

first; → derivative.

first derivative test
  آزمون ِ واخنه‌ی ِ نخست   
âzmun-e vâxane-ye naxost

Fr.: teste de la dérivée première   

In → calculus, a method for determining whether an → inflection point is a → local minimum, → local maximum, or neither.

first; → derivative; → test.

first dredge-up
  برونکشید ِ نخست   
borunkašid-e naxost

Fr.: premier dragage   

The → dredge-up occurring after core hydrogen burning as the core contracts before helium burning ignites (on the ascending giant branch). The hydrogen envelope becomes convective and this convective zone penetrates deep into the core dredging up material that has been processed by the central nuclear reactions. As a result the abundances of helium and nitrogen are boosted.

first; → dredge-up.

first law of thermodynamics
  قانون ِ نخست ِ گرماتوانیک   
qânun-e naxost-e garâtavânik

Fr.: première loi de la thermodynamique   

The total energy of a → closed system is constant. This means that energy can be changed from one form to another, or transferred from one system to another, but it cannot be created or destroyed. A mathematical formulation of the first law is: δQ = δU + δW, where δQ is the heat transferred to the system, δU the change in internal energy (resulting in a rise or fall of temperature), and δW is the work done by the system.

first; → law; → thermodynamics.

first light
  نخستین فروغ، ~ نور   
naxostin foruq, ~ nur

Fr.: première lumière   

The first astronomical observation done with a major newly built telescope.

first; → light.

First Point of Aries
  نقطه‌ی ِ آغاز ِ برّه   
noqte-ye âqâz-e barré (#)

Fr.: premier point de Bélier   

One of the two points on the celestial sphere where the ecliptic and the celestial equator crossed one another at → vernal equinox several thousands years ago.

first; → point; → Aries.

First Point of Libra
  نقطه‌ی ِ آغاز ِ ترازو   
noqte-ye âqâz-e tarâzu (#)

Fr.: permier point de Balance   

One of the two points on the celestial sphere where the ecliptic and the celestial equator crossed one another at → autumnal equinox several thousands years ago. Because of → precession, this equinoctial point no longer lies in Libra but in neighboring Virgo.

first quarter
  چارک ِ نخست   
cârak-e naxost

Fr.: premier quartier   

A → lunar phase that occurs in the middle of the interval between the → new Moon and the → full Moon, when half of the Moon's disk is illuminated. At first quarter, the Moon is situated at 90° east of the Sun.

first; → quarter.

first star
  نخستین ستاره   
naxostin setâré

Fr.: première étoile   

A member of the → Population III → massive stars that formed some 500 Myr after the → Big Bang. First stars had a simple chemical composition consisting only of H, He, and traces of 7Li and were very short-lived. They are the most likely sources of → reionization of the Universe, which put an end to the → Cosmic Dark Age.

first; → star.

first-order differential equation
  هموگش ِ دگرسانه‌ای ِ رایه‌ی ِ نخست   
hamugeš-e degarsâne-yi-ye râye-ye naxost

Fr.: équation différentielle du premier ordre   

A → differential equation containing only the first → derivative. For example, dy/dx = 3x and 2y(dy/dx) + 3x = 5.

first; → order; → differential; → equation.

first-order logic (FOL)
  گوییک ِ فراسنی ِ رایه‌ی ِ نخست، ~ فراسنهای ِ ~ ~   
guyik-e farâsani-ye râye-ye naxost, ~ farâsanhâ-ye ~ ~

Fr.: logique des prédicats du premier ordre   

A system of → formal logic that is an extension of → propositional logic. It is also known as → first-order predicate calculus and → predicate logic. FOL eliminates deficiencies of propositional logic by: representing → objects (their properties, relations and statements about them), introducing → variables, and introducing → quantifiers.

first; → order; → predicate; → logic.

first-order partial derivative
  واخنه‌ی ِ پاری ِ رایه‌ی ِ نخست   
vâxane-ye pâri-ye râye-ye naxost

Fr.: dérivée partielle du premier degré   

For a → function with several → variables, the derivative, done only once, with respect to one of the variables. For example ∂u/∂x for u = u(x,y).

first; → order; → partial; → derivative.

first-order predicate calculus
  افماریک ِ فراسنی ِ رایه‌ی ِ نخست   
afmârik-e farâsani-ye râye-ye naxost

Fr.: cacul des prédicats du premier ordre   

Same as → first-order logic.

first; → order; → predicate; → calculus.

first-order spectrum
  بیناب ِ رایه‌ی ِ نخست   
binâb-e râye-ye naxost

Fr.: spectre du premier ordre   

An optical spectrum, produced by a diffraction grating, in which the difference in path length of light from adjacent slits is one wavelength.

first; → order; → spectrum.

<< < -es -iv -ti 217 A s abe abs abs acc acc Ach act act ADa adi adv aff age Alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg arm art ass ast ast ast atm ato att aur aut axi B-t Bai Bal bar bar Be bed Bes BHB bif bim bin Bio bis bla ble blu bod Bol bor bou bra Bre bro Bul cag cal can Can car Car Cas cat CCD cel cen Cet cha cha che che chr cir cir cit cla clo clo clu Coa coe coh col Col col com com com com com com com com com con con con con con con con con con con con coo cor cor cor cos cos cos cou cou cra cri cro cry cul cur cyc D r dar dat day dea dec dec dec def def deg del den dep des det deu dex dif dif dif dim dip dir dis dis dis dis dis div dom dos dou dri Dum dus dyn dyn ear eas ecl Edd eff Ein eje ele ele ele ele eli emb emi Enc ene ens eph epo equ equ eru eth Eul eve evo exc exc exi exo exp exp ext ext fab fai Fan Fea fem fer fie fil fir fis fla flo flu foc for for Fou fra fre fre fro fun G r Gal gal gam gas Gau gel gen geo geo geo Gho gla goa gra gra gra gra gre Gre gro gyr had hal har har HD Hea Hel hel Her her hid hig Hip hom hor hot Hub Hub hun hyd hyd hyg Hyp ice ide ima imm imp imp inc ind ind ine inf inf inf ini ins ins int int int int int int int int int inv ion iro ise iso iso Jab jet Jov Jur Kel Kep kil kit Kui Lag lam lan Lar Lat law lea lem lep Li- lig lim lin lin lio lit loc lod lon Lor low Lum lun Lup Lyn mac mag mag mag mag mag mai man mar mas mas mat Max mea mec mel mer mes met met met mic mid mil Min mir mix mod mol mom Moo mor mov mul mur nab nar nat neb neg nes neu New New nig nod non non non Nor nua nuc nul Nun OBC obl obs occ oct off Ohm on- ope opp opt opt orb orb org Ori ort Ost out ove p m Pal par par par par Pas pat Peg Peo per per per per per pha Phe pho pho pho phy pin pla pla pla pla pla plu poi pol pol Pol pol pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro pro pro pse pul Pup Qua qua qua qua que rac rad rad rad rad rad rad ran rap ray rea rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot rur Sac sal sat sca sca Sch sci Scu sec sec Sed sel sem sen Ser Sey Sha she sho sid sig sim sin sip ske sli smo soc sol sol sol sol sol sou spa spa spe spe spe spe Spi spi spo squ sta sta sta sta Ste ste ste sto str str str sub sub sub sun sup sup sup sup sur sus sym syn T-s tar Tei tem ter tes the the the the thi thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur Tyc Typ ult unb und uni uni unr upp Urs vac van Var veg Ven ver vib vio vir vis vol VY war wat wav WC8 Web wes whi win WN1 wob wri X-r yoc zen Zhe > >>