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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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<< < -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 > >>

Number of Results: 13116 Search : far
parity violation
  اِناهش ِ همالی   
enâheš-e hamâli

Fr.: violation de la parité   

In quantum mechanics, the condition of → parity in the → weak interaction. For example, the emitted → beta particles in → radioactive decay of → cobalt-60 nuclei are not equally distributed between the two poles of cobalt-60. More beta particles emerge from one pole than the other, and it would be possible to distinguish the mirror image nuclei from their counterparts.

parity; → violation.

Parker instability
  ناپایداری ِ پارکر   
nâpâydâri-ye Parker

Fr.: instabilité de Parker   

A type of instability found in some astrophysical phenomena involving → magnetic fields; it arises if a gas layer is supported by the horizontal magnetic fields against → gravity. Also called → magnetic buoyancy. Briefly, this instability works as follows. Consider a uniform disk of gas which is coupled to a magnetici field that is parallel to the disk. Suppose that the disk is gravitationally stratified in the vertical direction, and is in dynamical equilibrium under the balance of gravity and pressure (thermal and magnetic). Now consider a small perturbation which causes the field lines to rise in certain parts of the disk and sink in others. Because of gravity, the gas loaded onto the field lines tends to slide off the peaks and and sink into the valleys. The increase of mass loads in the valleys makes them sink further, while the magnetic pressure causes the peaks to rise as their mass load decreases. Consequently, the initial perturbation is amplified, causing the production of density fluctuations in an initially uniform disk. The characteristic scale for the Parker instability is ~4πH, where H is the scale height of the diffuse component of the disk. For the Milky Way, where H ~ 150 pc, this scale is about 1-2 kpc. Numerical simulations show that the density contrast generated by the Parker instability is generally of order unity before the instability saturates. This implies that the Parker instability on its own may not be able to drive collapse on large scales. Nevertheless, it may trigger gravitational instability in a marginally unstable disk and/or induce strong motions in the medium, thereby acting as a source of turbulence on large scales (see, e.g., Houjun Mo, Frank van den Bosch, Simon White, 2010, Galaxy Formation and Evolution, The University Press, Cambridge, UK).

First studied by E. N. Parker, 1966, ApJ 145, 811; → instability.

Parker Solar Probe
  گمانه‌ی ِ خورشیدی ِ پارکر   
gomâne-ye xoršidi-ye Parker

Fr.: Parker Solar Probe   

A NASA space mission launched on August 12, 2018 to study the outer corona of the Sun at very close distances. Parker Solar Probe is the first space mission to penetrate into solar corona as close as about 10 solar radii. It will approach the Sun to this distance 25 times. Approaching the Sun to such distances is a big technological challenge. The main goals of the mission are to answer these questions: Why is the solar corona so hotter than the solar surface? How is the solar wind accelerated? How are the energetic particles produced and transported?

Named after the physicist Eugene Newman Parker (1927-), who proposed the existence of the solar wind and did pioneering work for its interpretation.

Parkes Selected Region (PSR)
  ناحیه‌ی ِ گزیده‌ی ِ پارکس   
nâhiye-ye gozide-ye Parkes

Fr.: Région sélectionnée de Parkes   

A catalog of 397 radio sources between declinations +20° and +27° which were compiled from a finding survey made at 635 MHz with the 64m radio telescope at the Australian National Radio Astronomy Observatory, Parkes, N.S.W. and published in 1968. Originally abbreviated PSR, this catalog, which is also called PKS, replaces and improves on four earlier lists (1964 to 1966).

Parkes, proper noun; selected, p.p. of → select; → region.

parsec (pc)
  پارسک   
pârsek (#)

Fr.: parsec   

A basic unit of astronomical distances, corresponding to a → trigonometric parallax of one second of arc. In other words, it is the distance at which one → astronomical unit (the mean radius of the Earth's orbit) subtends an angle of 1 arcsecond. 1 pc = 3.2616 → light-years = 206 265 astronomical units = 30.857 x 1012 km.

From parallax + second.

parselene
  پاراماه   
pârâmâh

Fr.: parasélène   

An optical phenomenon resulting from the refraction and reflection of moonlight within ice crystals in cirrus cloud; also known as paraselene, mock Moon or moondog. It is the lunar counterpart of the → parhelion.

From Gk. para- "beside," → para-, + selene "moon," from Gk. selene "moon," related to selas "light, brightness, flame."

Pârâ-, → para-, + mâh, → moon.

Parseval's theorem
  فربین ِ پارسوال   
farbin-e Parseval

Fr.: théorème de Parseval   

A theorem relating the → Fourier coefficients to the function that they describe. It states that: (1/L) ∫ |f(x)|2dx (integrated from x0 to x0 + L) = (a0/2)2 + (1/2) Σ (ar2 + br2) (summed from r = 1 to ∞). In other words, the sum of the moduli squared of the complex Fourier coefficients is equal to the average value of |f(x)|2 over one period.

Named after Marc-Antoine Parseval (1755-1836), French mathematician; → theorem.

part
  پار   
pâr

Fr.: partie   

1) A portion or division of a whole that is separate or distinct; piece, fragment, fraction, or section; constituent.
2) A section or division of a literary work (Dictionary.com).

M.E., from O.Fr. part "share, portion; character; dominion; side, path," from L. partem (nominative pars) "a part, piece, a share, a division; a party or faction," related to portio "share, portion," from PIE root *per- "to assign, allot;" cf. Pers. pâr, pâré "piece, part, portion, fragment;" as below.

Pâr, variant pâré "piece, part, portion," 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 assign;" Gk. peprotai "it has been granted;" L. pars, as above; Skt. purti- "reward;" Hitt. pars-, parsiya- "to break, crumble."

partial
  پاری، پارال   
pâri (#), pârâl

Fr.: partiel   

Being such in part only; not total or general; incomplete.
See also: → partial derivative, → partial differential equation, → partial eclipse, → partial ionization zone, → partial lunar eclipse, → partial solar eclipse, → partial truth.

M.E. parcial, from O.Fr. parcial, from M.L. partialis "pertaining to a part," from L. pars, → part; → -al.

part; → -al.

partial derivative
  واخنه‌ی ِ پاری   
vâxane-ye pâri

Fr.: dérivée partielle   

The derivative of a function of two or more variables, e.g., z = f(x,y), with respect to one of the variables, the others being considered constants (denoted ∂z / ∂x).

partial; → derivative.

partial differential equation
  هموگش ِ دگرسانه‌ای با واخنه‌ی ِ پاری   
hamugeš-e degarsâne-yi bâ vâxane-ye pâri

Fr.: équation différentielle aux dérivées partielles   

A type of differential equation involving an unknown function (or functions) of several independent variables and its (or their) partial derivatives with respect to those variables.

partial; → differential; → equation.

partial eclipse
  گرفت ِ پاری   
gereft-e pâri

Fr.: éclipse partielle   

An eclipse that is not total. → partial lunar eclipse, → partial solar eclipse.

partial; → eclipse.

partial ionization zone
  زنار ِ یونش ِ پاری   
zonâr-e yoneš-e pâri

Fr.: zone d'ionisation partielle   

One of several zones of the stellar interior where increased → opacity can provide the → kappa mechanism to drive → pulsations. See also → Kramers' law. In these zones where the gases are partially ionized, part of the energy released during a layer's compression can be used for further ionization, rather than raising the temperature of the gas. Partial ionization zones modulate the flow of energy through the layers of the star and are the direct cause of → stellar pulsation. The partial ionization zones were first identified by the Russian astronomer Sergei A. Zhevakin (1916-2001) in the 1950s. In most stars there are two main ionization zones. The hydrogen partial ionization zone where both the ionization of neutral hydrogen (H ↔ H+ + e-) and the first ionization of helium (He ↔ He+ + e-) occurs in layers with a characteristic temperature of 1.5 x 104 K. The second, deeper zone is called the He+ partial ionization zone, and involves the second ionization of helium (He+↔ He++ + e-), which occurs deeper at a characteristic temperature of 4 x 104 K. The location of these ionization zones within the star determines its pulsational properties. In fact if the → effective temperature of the star is ≥ 7500 K, the pulsation is not active, because the ionization zones will be located very near to the surface. In this region the density is quite low and there is not enough mass available to drive the oscillations. This explains the blue (hot) edge of the instability strip on the → H-R diagram. Otherwise if a star's surface temperature is too low, ≤ 5500 K, the onset of efficient convection in its outer layers may dampen the oscillations. The red (cool) edge of the instability strip is believed to be the result of the damping effect of convection. He+ ionization is the driving agent in → Cepheids. See also → gamma mechanism.

partial; → ionization; → zone.

partial lunar eclipse
  مانگ‌گرفت ِ پاری   
mânggereft-e pâri

Fr.: éclipse partielle de lune   

A → lunar eclipse when the Earth's → umbra passes over only part of the Moon, causing only moderate darkening of the full Moon. See also → penumbral lunar eclipse.

partial; → lunar; → eclipse.

partial solar eclipse
  خورگرفت ِ پاری   
xorgereft-e pâri

Fr.: éclipse partielle de soleil   

A → solar eclipse when only the → penumbra of the Moon touches the Earth. The → umbra passes either just above the North Pole or just below the South Pole, missing the Earth.

partial; → solar; → eclipse.

partial truth
  راستینی ِ پاری، ~ پارال   
râstini-ye pâri, ~ pârâl

Fr.: vérité partielle   

A → truth value in → fuzzy logic where it can range between "completely true" and "completely false."

partial; → truth.

participate
  پارگرتیدن   
pârgertidan

Fr.: participer   

To take part, be or become actively involved.

From L. paticipatus p.p. of partcipare "to share," from particeps "partaking, sharing," from part-, pars "part," → partial, + capere "to take," → concept.

Pârgertidan, from pâr "part," → partial, + gertidan "to take," → concept.

participation
  پارگرت   
pârgert

Fr.: participation   

An act or instance of participating. The fact of taking part.

Verbal noun of → participate.

participle
  پارگرته   
pârgerté

Fr.: participe   

A lexical form derived from a verb, that has some of the characteristics and functions of both verbs and adjectives. In most Indo-European languages participles are used to express participation in an action (present participle) or relate to a completed action (past participle). They can also appear in attributive form as adjectives.

M.E., from O.Fr. participle, variant of participe, from L. participium, literally "a sharing, partaking," from particeps "sharing, partaking," → participate.

Pârgerté, from pârgert present stem of pârgertidan, → participate, + nuance suffix .

particle
  ذره، پارول   
1) , 2) zarré (#), 1), 2), 3) pârul

Fr.: particule   

1) A unit of → matter smaller than the → atom or its main components. The term particle also includes any (currently hypothetical) new particles that might be discovered, such as the supersymmetric partners of the → quarks and → leptons and → bosons.
2) Mechanics: A material body (a body possessing mass) the size of which can be neglected in investigating its motion.
3) Grammar: In some languages, a word that has a grammatical function but does not fit into the main parts of speech (i.e. → noun, → verb, → adverb, → preposition). For example, in English, off, on, out, and up in call off, pass on, rule out, and grow up, respectively.
See also:
alpha particle, → antiparticle, → astroparticle physics, → beta particle, → charged particle, → elementary particle, → energetic solar particle, → exchange particle, → Lagrangian particle, → nanoparticle, → particle horizon, → particle nature, → particle physics, → relativistic particle, → resonance particle, → sink particle, → Smoothed Particle Hydrodynamics, → strange particle, → subatomic particle, → test particle, → virtual particle, → wave-particle duality.

From L. particula "little bit or part," diminutive of pars (genitive partis), from PIE base *per- "to assign, allot;" cf. Mid.Pers. pârag "gift, offering, bribe;" Mod.Pers. pâreh "gift" (→ partial); Gk. porein "to provide, give, grant," peprotai "it has been granted;" Skt. purtá- "gift, pay, reward."

Zarré, from Ar. dharrat "particle." Pârul, from pâr, → part, + -ul, → -ule.

<< < -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 > >>