An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13048 Search : far
equatorial wind
  باد ِ هموگاری   
bâd-e hamugâri

Fr.: vent équatorial   

A slow, dense → stellar wind (high → mass loss rate) emanating from equatorial regions of a → B[e] star. The equatorial and → polar winds are the two main wind components in B[e] stars. The mechanism suggested to explain this wind morphology is the rotationally induced → bistability mechanism.

equatorial; → wind.

equi-
  هموگ-   
hamug-

Fr.: équi-   

A prefix meaning "equal," as in → equinox, → equilibrium, → equipartition.

M.E., from L. aequi-, combining form representing aequus, → equal.

Hamug-, → equal.

equiaxial
  هموگ-آسه   
hamug-âsé

Fr.: équiaxe   

Math.: having three axes of the same length. Also equiaxed.
Physics: A crystal exhibiting similar dimensions in all directions.

equi-; → axis.

equilateral triangle
  سه‌بر ِ سه-پهلو-برابر   
sebar-e sé-pahlu-barâbar (#)

Fr.: triangle équilatéral   

A triangle having three equal sides.

equi-, → lateral, → triangle.

Sé-pahlu-barâbar, from , → three, pahlu, → side, barâbar, → equal.

equilibrium
  ترازمندی   
tarâzmandi (#)

Fr.: équilibre   

A state of balance or rest between the forces operating on or within a physical system. → stable equilibrium; → unstable equilibrium; → dynamical equilibrium.

From L. æquilibrium, from æquus, → equal + libra "a balance, scale."

Tarâzmandi, noun of tarâzmand "in equilibrium," from tarâz "level; a level" + possession suffix -mand. The first component from tarâzu "balance, scales," Mid.Pers. tarâzên-, taraênidan "to weigh;" Proto-Iranian *tarāz-, from *tarā- "balance, scale" (cf. Skt. tulā- "scales, balance, weight," from tul- "to weigh, make equal in weight, equal," tolayati "weighs, balances;" L. tollere "to raise;" Gk. talanton "balance, weight," Atlas "the Bearer" of Heaven;" Lith. tiltas "bridge;" PIE base telə- "to lift, weigh") + Av. az- "to convey, conduct, drive," azaiti drives" (cf. Skt. aj- "to dive, sling," ájati "drives," ajirá- "agile, quick;" Gk. agein "to lead, guide, drive, carry off;" L. agere "to do, set in motion, drive," from PIE root *ag- "to drive, move," → act).

equilibrium partitioning
  پرکه‌بندی ِ ترازمند   
parkebandi-ye tarâzmand

Fr.: équilibre de partition   

A concept whereby chemical → concentrations among geological or environmental media are at equilibrium, and therefore the partitioning of metals in those media can be predicted based on → partition ratios.

equilibrium; → partitioning.

equilibrium position
  نهش ِ ترازمندی   
naheš-e tarâzmandi (#)

Fr.: position d'équilibre   

The position of an oscillating body at which no net force acts on it.

equilibrium; → position.

equilibrium state
  استات ِ ترازمندی، حالت ِ ~   
estât-e tarâzmandi, hâlat-e ~

Fr.: état d'équilibre   

A state in which a → thermodynamic system is in → thermodynamic equilibrium.

equilibrium; → state.

equilux
  هموگتاب   
hamugtâb

Fr.: équilux   

The date on which the day and night have exactly the same length. Contrary to the widespread statement, the day and night are not equal at the → equinox. The higher the → latitude, the greater the difference. In fact the day and night lengths are equal at the equinox only if the strict theoretical definition is used, according to which sunset and sunrise are the moments when the center of the Sun crosses the → horizon. There are two reasons for this inequality: 1) The Sun is a disk, not a point source. It is about 30 arc minute wide, hence sunrise corresponds to the moment the top of the disk (and not its center) emerges out of the horizon. Similarly, sunset is when the last part of the disk sinks below the horizon. The Sun takes about a minute to move from its center to its edge (the Earth rotates about 1 degree in 4 minutes). This sums to two minutes (a minute for sunset and a minute for sunrise) that adds to 4 minutes in the total difference. 2) The atmosphere acts as a lens, and slightly bends the Sun's rays because of the → atmospheric refraction. When we look at the setting Sun, the fact is that it was already set. Unlike the equinox, which is a fixed date all-over the globe, the date of the equilux is dependent upon the → latitude of the observer. Between the poles and about 20 degrees latitude, it is generally a few days before the → vernal equinox or a few days after the → autumnal equinox .

equi-; → lux.

equinoctial
  هموگانی   
hamugâni

Fr.: équinoxial   

Of or relating to an equinox or to the equality of day and night.

Adjective of → equinox.

equinoctial colure
  کلدم ِ هموگانی   
koldom-e hamugâni

Fr.: colure d'équinoxe   

The great circle of the celestial sphere through the celestial poles and equinoxes; the hour circle of the vernal equinox. → colure.

equinoctial; → colure.

equinoctial points
  نقطه‌ها‌ی ِ هموگانی   
noqtehâ-ye hamugâni

Fr.: points équinoxiaux   

One of the two points of intersection of the ecliptic and the celestial equator. Same as equinox.

equinoctial; → point.

equinox
  هموگان   
hamugân

Fr.: équinoxe   

1) One of the two points on the → celestial sphere where the → celestial equator intersects the → ecliptic, that is when the apparent → ecliptic longitude of the Sun is 0° or 180°.
2) Either of the times at which the center of the Sun's disk passes through these points. → autumnal equinox; → vernal equinox.
At equinox, the length of the day and the night are equal all over the globe. The equinox is not a fixed point; it moves due to → precession and → nutation. If only precession is considered, we deal with the → mean equinox of date. If nutation is also taken into account, then we are concerned with the → true equinox.

M.E., from O.Fr. équinoxe, from M.L. equinoxium "equality of night (and day)," from L. æquinoctium, from æquus, "→ equal" + nox "→ night" (gen. noctis). In Gk. isimeria "equal day," from isos "equal," → iso-, + hemera "day."

From hamug, → equal, + -ân suffix denoting time and place.

equipartition of energy
  هموگپرکش ِ کاروژ   
hamugparkeš-e kâruž

Fr.: équipartition de l'énergie   

1) General: Equal sharing of the → total energy among all → components of a → system.
2) In the → kinetic theory of gases, the → theorem according to which → molecules in → thermal equilibrium have the same average energy (1/2 kT) associated with each independent → degree of freedom of their motion.

equi-; → partition.

equipotential surface
  رویه‌ی ِ هموگ-توند   
ruye-ye hamugtavand

Fr.: surface équipotentielle   

An imaginary surface surrounding a body, or group of bodies, over which the gravitational field is of constant strength and, at all points, is directed perpendicular to the surface. For a single star the surface is spherical. In a close binary system the equipotential surface of the components interact to become hourglass-shaped. → Roche lobe; → Lagrangian points.

From → equi-; → potential; → surface.

equivalence
  هموگ‌ارزی   
hamug-arzi (#)

Fr.: équivalence   

The state or fact of being equivalent; equality in value, force, significance, etc. → covalence.

From M.F. from M.L. æquivalentia, from L. æquivalent-, → equivalent.

Hamug-arzi, noun of hamug-arz, → equivalent.

equivalence principle
  پروز ِ هموگ‌ارزی   
parvaz-e hamug-arzi

Fr.: principe d'équivalence   

A fundamental concept of physics, put forward by A. Einstein, that states that gravitational and inertial forces are of a similar nature and indistinguishable. In other words, acceleration due to gravity is equivalent to acceleration due to other forces, and gravitational mass is the same as inertial mass. Same as the → principle of equivalence.

equivalence; → principle.

equivalent
  هموگ‌ارز   
hamug-arz

Fr.: équivalent   

Equal in value, measure, force, effect, significance, etc.

From L.L. æquivalentem (nominative æquivalens) "equivalent," p.p. of æquivalere "be equivalent," from L. æquus, → equal + valere "to be worth; be strong."

Hamug-arz, from hamug-, → equi-, + arz stem of arzidan "to be worth," arzân "worthy; of small value, cheap," arj "esteem, honour, price, worth;" Mid.Pers. arz "value, worth," arzidan "be worth," arzân "valuable;" Av. arəjaiti "is worth," arəja- "valuable," arəg- "to be worth;" cf. Skt. arh- "to be worth, to earn," árhant- "worthy person;" Gk. alphanein "to bring in as profit," alphein "to ear, obtain;" Lith. algà "salary, pay;" PIE base *algwh- "to earn; price, value."

equivalent depth
  ژرفای ِ هم-ارز   
žarfâ-ye ham-arz

Fr.: profondeur équivalente   

A measure of the number of particles passing a given point in a → planetary ring per unit time. It is obtained by multiplying the physical width of the ring by its average → optical depth. For the variable-width eccentric rings of → Uranus, equivalent depth remains almost constant around a given ring (Ellis et al., 2007, Planetary Ring Systems, Springer).

equivalent; → depth.

equivalent positions
  نهش‌های ِ هموگ‌ارز   
nehešhâ-ye hamug-arz

Fr.:   

Complete set of points in any given space group which are obtained by performing the symmetry operations of the space group on a single point (x, y, z).

equivalent; → position.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara Arc ari Arr ash ass ast ast asy atm ato att aut ave axi Bab bal Bal bar bar bea Bek Bes bia Big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo cal cal can cap car Car cat cat CCD Cen cen CH 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 con Cop Cor cor cor cos cos cou cou Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp opt opt orb ord ori ort osc out ove oxi pai pan par par par par pas pea pen per per per per Per per pha phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar 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 Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>