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: 13116 Search : far
protester
  پاخوسگر، پاخوسنده   
pâxosgar, pâxosandé

Fr.: protestataire   

A person who publicly demonstrates opposition to something. Also protestor.

protest; → -er.

Proteus
  پروتءوس   
Proteus

Fr.: Protée   

One of the largest of → Neptune's known moons discovered in 1989 by the Voyager 2 space probe. Proteus revolves around Neptune at a distance of about 92,800 km, completing one orbit in 26 hours, 54 minutes. Proteus is about 400 m in diameter, larger than → Nereid. Orbiting the planet in the same direction as Neptune rotates, Proteus remains close to Neptune's equatorial plane. Proteus is irregularly shaped and heavily cratered, but it shows no sign of geological modification. In fact Proteus is about as large as a satellite can be without being pulled into a spherical shape by its own gravity. Proteus is one of the darkest objects in the solar system. Like Saturn's moon Phoebe, Proteus reflects only six percent of the sunlight that it receives.

Originally designated S/1989 N 1, Proteus is named after the shape-changing sea god of Greek mythology.

protium
  پروتیوم   
protiom

Fr.: protium   

The lightest and most common → isotope of → hydrogen, with one → proton and no → neutrons; symbol 1H. See also → deuterium and → tritium.

From Gk. protos "first" + L. → -ium.

proto-
  پوروا-   
purvâ-

Fr.: proto-   

A combining form meaning "first, foremost, earliest form of," used in the formation of compound words such as → protogalaxy, → protoplanet, → protostar, etc.

From Gk. proto-, combining form of protos "first," superlative of pro "before," cognate with O.S. pruvu "first;" Rus. pervyy "first;" Av. pauruua-, as below.

Purvâ-, from O.Pers. paruviya- "former, initial," Av. pourva-, pouruuiia-, pauruua-, paoiriia- "first, initial, former;" cf. Skt. purva- "first, former, being before;" Tokharian B parwe "first;" PIE base *prwos "first."

Proto-Indo-European (PIE)
  پوروا-هند-و-ارویایی   
purvâ-hend-o-orupâyi

Fr.: proto-indoeuropéen   

The hypothetical but strongly evidenced common ancestor of the Indo-European languages. PIE words are reconstructed from extant Indo-European languages. There is no clear agreement on exactly where or when the speakers of PIE lived. It is believed that most of the subgroups diverged and spread out over much of Europe, Iran, and northern Indian subcontinent during the fourth and third millennia BC. See also → proto-language.

proto-; + Indo-, → Indus, + → European.

proto-language
  پوروا-زبان   
purvâ-zabân

Fr.: proto-langue   

The hypothetical and typically extinct language which is believed to be the ancestor of a group of languages of the same family. Historical linguistics uses comparative study of the languages of a family to reconstruct the ancestral language even though in most cases it was never recorded. Some examples are → Proto-Indo-European, Proto-Germanic, Proto-Romance, Proto-Sino-Tibetan, etc.

proto-; → language.

protocluster
  پوروا-خوشه   
purvâ-xušé

Fr.: proto-amas   

A very huge mass of gas which will give rise to a cluster of galaxies.

proto-; → cluster.

protocol
  پوروا-بند، پوروابند   
purvâ-band

Fr.: protocole   

Computers: A set of rules and methods used for communication and transmission of data between different computer systems. Protocols may be implemented by hardware, software, or a combination of the two. Simple protocols define the behavior of a hardware connection and help with error detection of the bit stream. High level protocols deal with the data formatting, including the syntax of messages, the terminal to computer dialogue, character sets, sequencing of messages etc.

M.E. prothogall "draft of a document," from M.Fr. prothocole, from M.L. protocollum "draft," literally "the first sheet of a volume" (on which contents were written), from Gk. protokollon "first leaf glued to the rolls of papyrus describing its contents," from → proto- "first" + kolla "glue."

Purvâband from purvâ-, → proto-, + band "joint; joined," past stem of bastan "to bind; to shut; to form seed buds; to clot," from Mid.Pers. bastan/vastan "to bind, shut," Av./O.Pers. band- "to bind, fetter," banda- "band, tie;" Skt. bandh- "to bind, tie, fasten;" PIE *bhendh- "to bind," cf. Ger. binden, E. bind.

protogalaxy
  پوروا-کهکشان   
purvâ-kahkešân

Fr.: proto-galaxie   

A huge mass of gas that by contraction and condensation becomes a galaxy of stars. A galaxy during the early phase, before it has developed its present shape and stellar/gas content.

proto-; → galaxy.

protolunar disk
  گرده‌ی ِ پوروا-مانگی   
gerde-ye purvâ-mângi

Fr.: disque proto-lunaire   

A dense disk of liquid and vapor supposed to have formed around the Earth below the Roche limit after the proto-Earth was impacted by a Mars-sized object. The Moon was accreted from the Earth's mantle material froming the disk. See also → Theia (S. Charnoz and C. Michaut, 2015, arxiv.1507.05658).

proto-; → lunar; → disk.

proton
  پروتون   
proton (#)

Fr.: proton   

A particle of the hadron family which is one of the two particles that make up atomic nuclei. It has an electric charge of one positive fundamental unit, a diameter of about 1.65 x 10-13 cm, and a mass of about 1.67 x 10-24 g (about 938 MeV c-2).

From Gk. proton, neuter of protos "first." Coined by Eng. physicist Ernest Rutherford (1871-1937).

proton temperature
  دمای ِ پروتونی   
damâ-ye protoni

Fr.: température protonique   

The temperature in the → solar wind, as derived from the mean kinetic energy of protons: mv2/2 = (3/2)kTp, where k is → Boltzmann's constant. There are two types of proton temperature: parallel temperature, measured from protons moving parallel to the magnetic field, and perpendicular temperature relating to protons at right angles to the magnetic field. The proton temperature is usually derived using particle detectors on board space probes that determine the velocity → distribution function of the particles from their energies (N. Meyer-Vernet, 2007, Basics of the Solar Wind, Cambridge Univ. Press). See also → electron temperature.

proton; → temperature.

proton-proton chain
  زنجیره‌ی ِ پروتون-پروتون   
zanjire-ye proton-proton (#)

Fr.: chaîne proton-proton   

A series of → thermonuclear reactions, taking place mainly in → low-mass stars, such as the Sun, which transforms four hydrogen nuclei (protons) into one helium (4He) nucleus and thereby generates energy in the stellar core. First, two protons (1H) combine to form a → deuterium nucleus (2H) with the emission of a → positron (e+) and a → neutrino (ν): 1H + 1H → 2H + e+ + ν. The deuterium nucleus then rapidly captures another proton to form a helium-3 nucleus (3He), while emitting a → gamma ray (γ): 2H + 1H → 3He + γ. There are three alternatives for the next step. In the PP I chain, occurring in 86% of the cases, two 3He nuclei fuse to a final 4He nucleus while two protons are released: 3He + 3He → 4He + 1H + 1H. The mass of the resulting 4He nucleus is less than the total mass of the four original protons used to produce 4He (→ mass defect). The difference, ~ 0.7% of the total mass of the protons, is converted into energy and radiated by the Sun. In this process, the Sun loses some 4 million tons of its mass each second. See also → CNO cycle.

proton; → chain.

proton-proton reaction
  واژیرش ِ پروتون-پروتون   
vâžireš-e-e proton-proton

Fr.: réaction proton-proton   

A → thermonuclear reaction in which two protons collide at very high velocities and combine to form a → deuterium. See also → proton-proton chain.

proton; → reaction.

protoneutron star
  ستاره‌ی ِ پوروا-نوترونی   
setâre-ye purvâ-notroni

Fr.: proto-étoile à neutrons   

A compact, hot, and → neutrino-rich object that results from a → supernova explosion and is a transition between an → iron core and a → neutron star or → black hole. The life span of a protoneutron star is less than one minute.

proto-; → neutron; → star.

protoplanet
  پوروا-سیاره   
purvâ-sayyâré

Fr.: protoplanète   

A stage in the formation of a → planet, which comes about from the aggregation of → planetesimals. The protoplanet eventually becomes a planet by → accretion of material from a → protoplanetary disk.

proto- + → planet.

protoplanetary disk
  گرده‌ی ِ پوروا-سیاره‌ای   
gerde-ye purvâ-sayyâreyi

Fr.: disque protoplanétaire   

A → circumstellar disk of gas and dust surrounding a → pre-main sequence star from which planetary systems form. Protoplanetary disks are remnants of → accretion disks which bring forth stars. Typically, their sizes are ~100-500 AU, masses ~10-2 solar masses, lifetimes ~106-107 years, and accretion rates ~10-7-10-8 solar masses per year. According to the standard theory of planet formation, called core accretion, planets come into being by the growth of → dust grains which stick together and produce ever larger bodies, known as → planetesimals. The agglomeration of these planetesimals of 100 to 1000 km in size into rocky Earth-mass planets is the main outcome of this theory. Beyond the → snow line in the disk, if the masses of these cores of rock and ice grow higher than 10 times that of Earth in less than a few million years, gas can rapidly accrete and give rise to giant gaseous planets similar to → Jupiter. If core building goes on too slowly, the disk gas dissipates before the formation of → giant planets can start. Finally the left-over planetesimals that could not agglomerate into rocky planets or core of giant planets remain as a → debris disk around the central object that has become a → main sequence star. An alternative to core accretion theory is formation of planets in a massive protoplanetary disk by → gravitational instabilities. The validity of these two theories is presently debated. See also → protoplanet.

protoplanet; → disk.

protoplanetary nebula
  پیش-میغ ِ سیاره‌ای   
piš-miq-e sayyâre-yi

Fr.: pré-nebuleuse planétaire   

preplanetary nebula.

proto-; → planetary; → nebula.

protoplasm
  پوروا-پلسم   
purvâplasm

Fr.: protoplasme   

The fluid substance within the living cell that consists of two major divisions, the cytoplasm and the nucleoplasm (cell nucleus). It is composed mainly of nucleic acids, proteins, lipids, carbohydrates, and inorganic salts.

proto- + -plasm, → plasma.

protosolar
  پوروا-خورشیدی   
purvâ-xoršidi

Fr.: protosolaire   

Describing the conditions prior to the formation of the → solar system, or pertaining to the → protostar that became the → Sun.

proto- + → solar.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc 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 coo Cor Cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg ura uti val var vec Vel ver Ver vie Vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>