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: 3079 Search : on
polyhedron
  بلدیمه   
boldimé

Fr.: polyèdre   

1) Geometry: A three-dimensional figure formed by several → polygons.
2) A set P ⊆ ℜn is a polyhedron if there is a system of finitely many unequalities Ax ≤ b such that P = {x ∈ ℜn | Ax ≤ b}.

poly-; → hedron.

polynomial equation
  هموگش ِ بلنامین   
hamugeš-e bolnâmin

Fr.: équation polynomiale   

An equation of the form a0 + a1x + a2x2 + ... + anxn, where a0 ... an are → real numbers and an≠ 0. Same as → algebraic equation.

polynomial; → equation.

popularization
  مردم‌پسندانش، مردمانش   
mardom-pasandâneš, mardomâneš

Fr.: popularisation   

The act of popularizing.

popularize; → -tion.

population
  پُرینش   
porineš

Fr.: population   

Statistics: Any finite or infinite set of individuals, items, or data subject to a statistical study. → disk population; → halo population; → population inversion; → Bose-Einstein distribution.

Verbal noun of populate, from M.L. populatus, p.p. of populare "to inhabit," from L. populus "people."

In the IE languages the concepts of "full, many, multitude" and "people, group, herd, flock" are related. In Pers. several variants of por "full, much, many" denote "group, population," as in Lori, Qâyeni bor "group, tribe, herd," Torbat-Heydariyeyi, Qomi borr "heap, bundle, group," Qomi borreh "group, assemblage of people," Pashtu parrak "flock, herd," Urdu para "flock, herd," Lârestâni baila "group, tribe," Tabari balik "herd, flock;" other examples from literary Pers. bâré "herd, flock," parré "a rank or file of soldiers, a circular disposition of troops." Therefore, porineš "population," verbal noun of porinidan "to populate," infinitive of porin "populous," from por "mutitude, many, full" + -in attribution suffix. Por, from Mid.Pers. purr "full;" O.Pers. paru- "much, many;" Av. par- "to fill," parav-, pauru-, pouru- "full, much, many;" PIE base *pelu- "full," from *pel- "to be full;" cf. Skt. puru- "much, abundant;" Gk. polus "many," plethos "great number, multitude;" O.E. full.

Population I star
  ستاره‌ی ِ پرینش ِ I   
setâre-ye-e porineš-e I

Fr.: étoiles de population I   

A member of a class of relatively young stars, containing a large fraction of → metals, found mainly in the disk of the Galaxy.

population; I, Roman number 1; → star.

Population II star
  ستاره‌ی ِ پرینش ِ II   
setâre-ye porineš-e II

Fr.: étoiles de population II   

A member of a population of relatively old stars, containing a small fraction of → metals, found mainly in the → halo of the Galaxy and in → globular clusters.

population; II, Roman number 2; → star.

Population III star
  ستاره‌ی ِ پرینش ِ III   
setâre-ye porineš-e III

Fr.: étoile de population III   

A member of the first generation of stars, formed out of pristine gas, enriched by → primordial nucleosynthesis alone. The material from which these stars formed consisted mostly of hydrogen and helium. Because neutral hydrogen clouds were free of dust, their cooling mechanism was drastically ineffective. As a result, these star forming clouds had a much higher temperature than in the present epoch, and their → Jeans mass was much higher. Therefore, these first generation of stars were principally massive, with a typical mass scale of order of about 100 Msun. Population III stars started forming about 300 million years after the → Big Bang at → redshifts between 50 and 6, when the Universe had between 1 and 5% of its present age. These stars were probably responsible for the → reionization of the Universe. Given their high mass, they lived only a few million years ending with either a → pair-instability supernova phase or a direct collapse to a → black hole. Population III stars thus initiated the chemical enrichment of the Universe and opened the way to more normal modes of star formation, namely → Population II. Some models predict a bimodal → initial mass function for the first stars, allowing also for solar mass stars. See also → extremely metal-poor star.

population; III, Roman number 3; → star.

population inversion
  واگردانی ِ پرینش، وارونش ِ ~   
vâgardâni-ye porineš, vâruneš-e ~

Fr.: inversion des populations   

In physics, specifically statistical mechanics, the state of an atomic or molecular system in which the number of members in an excited state is larger than those in lower energy states. → optical pumping; → inverted population.

population; → inversion.

portion
  پارش، پاره، پارگ   
pâreš (#), pâre (#), pârag (#)

Fr.: portion   

1) A part of any whole, either separated from or integrated with it.
2) To divide into or distribute in portions or shares.

M.E. porcion, from O.Fr. porcion "part, portion, share," from partion- "share, part, piece," related to pars, → part.

Pâreš, from pâr "part, portion, piece" (variants pâré, parré "portion, segment (of an orange)," pargâlé, "piece, portion; patch;" (dialects Kermâni pariké "portion, half;" Tabari perik "minute quantity, particle;" Lârestâni pakva "patch;" Borujerdi parru "patch"); Mid.Pers. pârag "piece, part, portion; gift, offering, bribe;" Av. pāra- "debt," from par- "to remunerate, equalize; to condemn;" PIE *per- "to sell, hand over, distribute; to assigne;" Gk. peprotai "it has been granted;" L. pars, as above; Skt. purti- "reward;" Hitt. pars-, parsiya- "to break, crumble") + -eš suffix.

position
  ۱) نهش؛ ۲) نهش‌دادن   
1) neheš (#); 2) neheš-dâdan

Fr.: 1) position; 2) positionner   

1a) Condition with reference to place; location; situation.
1b) A place occupied or to be occupied. → mean position.
2a) To put in a particular or appropriate position; place.
2b) To determine the position of; locate.

M.E. posicioun, from O.Fr. posicion, from L. positionem "act or fact of placing, position, affirmation," from positus, p.p. stem of ponere "to put, place."

Neheš, verbal noun from nehâdan "to place, put; to set;" Mid.Pers. nihâtan, from ne-, ni- "down; into," → ni- (PIE), + dâ- "to put; to establish; to give," dadâiti "he gives;" cf. Skt. dadâti "he gives;" Gk. didomi "I give;" L. do "I give;" PIE base *do- "to give"). Neheš-dâdan, from neheš "position," + dâdan "to give, yield, put," → datum.

position angle
  زاویه‌ی ِ نهش   
zâviye-ye neheš

Fr.: angle de position   

The convention for measuring angles on the sky in astronomy (Abbreviated as PA). It is the direction of an imaginary arrow in the sky, measured from north through east: 0° = north, 90° = east, 180° = south, and so on to 359° and back to 0°. Applied to a binary system it is the direction of a secondary body or feature from a primary, measured in the system. .

position; → angle.

position switching
  دگربانی ِ نهش   
degarbâni-ye neheš

Fr.: permutation de position   

In single dish astronomy, an observing mode in which the telescope is moved between the object position and a user defined reference position. The aim is to eliminate unwanted signals in the baseline. → beam switching; → frequency switching.

position; → switching.

positional
  نهشی   
neheši (#)

Fr.: de position, positionnel   

Relating to or determined by position.

position; → -al.

positional astronomy
  اخترشناسی ِ نهشی   
axtaršenâsi-ye neheši

Fr.: astronomie de position   

The branch of astronomy that is used to determine the location of objects on the celestial sphere, as seen at a particular date, time, and location on the Earth. Same as → spherical astronomy.

positional; → astronomy.

positional notation
  نمادگان ِ نهشی   
nemâdgân-e neheši

Fr.: notation positionnelle   

A system of representing → numbers in which the → position of a → digit in a string of digits affects its value. The decimal system is a positional notation for expressing numbers. Same as → place-value notation and → positional number system.

positional; → notation.

positional number system
  راژمان ِ عددی ِ نهشی   
râžmân-e adadi-ye neheši

Fr.: système de numération positionnel   

A → number system in which the value of each digit is determined by which place it appears in the full number. The lowest place value is the rightmost position, and each successive position to the left has a higher place value. In the → number system conversion, the rightmost position represents the "ones" column, the next position represents the "tens" column, the next position represents "hundreds", etc. The values of each position correspond to powers of the → base of the number system. For example, in the usual decimal number system, which uses base 10, the place values correspond to powers of 10. Same as → place-value notation and → positional notation. See also → number system conversion.

positional; → number; → system.

positioning
  نهش‌داد، نهشداد   
nehešdâd

Fr.: positionnement   

The act or process of putting in a particular position or determining the psition of.

Verbal noun of → position; → -ing.

positive correlation
  هم‌باز‌آنش ِ داهیدار   
hambâzâneš-e dâhidâr

Fr.: correlation positive   

Same as → direct correlation.

positive; → correlation.

positron
  پوزیترون   
pozitron

Fr.: positron   

The → antiparticle of the → electron, which has the same → mass, → spin, and → electric charge as the electron, but the charge is → positive. Positrons may be generated by → radioactive decay or by → pair production from energetic → gamma ray photons.

From posi(tive), → positive + (elec)tronelectron.

positronium
  پوزیترونیوم   
pozitroniom

Fr.: positronium   

A short-lived bound state of a positron and an electron.

From → positron + -ium (as in barium, titanium), from N.L., from L. neuter suffix.

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