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
phosphorus
  ۱) فسفر؛ ۲) روجا، ستاره‌ی ِ بامدادی   
1) fosfor (#); 2) rujâ, setâre-ye bâmdâdi (#)

Fr.: phosphore   

1) Nonmetallic chemical element; symbol P. → Atomic number 15; → atomic weight 30.97376; → melting point 44.1°C; → boiling point about 280°C. It was discovered by the German merchant Hennig Brand in 1669.
2) Greek name for the planet → Venus when it appears as a → morning star.

L. Phosphorus "morning star," from Gk. Phosphoros "morning star," literally "light bearing," from phos "light" + phoros "bearer," from pherein "to carry," cognate with Pers. bordan "to carry, lead" (→ periphery). The chemical element is such called because of its white color.

1) Fosfor, loan from Fr.
2) → morning star.

photino
  فوتینو   
fotino (#)

Fr.: photino   

The supersymmetric partner of the → photon.

From phot, from → photon + -ino supersymmetric particle suffix.

photoabsorption
  شید-درشم   
šid-daršam

Fr.: photoabsorption   

A situation in which all of the energy of a photon is transferred to an atom, molecule, or nucleus.

photo- + → absorption.

photocathode
  شید-کاتود، نور-کاتود   
šid-kâtod, nur-kâtod

Fr.: photocathode   

Electrode capable of releasing electrons when illuminated.

photo- + → cathode.

photochemistry
  شید-شیمی، نور-شیمی   
šid-šimi, nur-šimi

Fr.: photochimie   

The study of the chemical and physical changes occurring when a molecule or atom absorbs photons of light.

photo- + → chemistry.

photodesorption
  شید-واشم   
šid-vâšam

Fr.: photodésorption   

Th desorption of surface substances by ultraviolet radiation.

photo-; → desorption.

photodisintegration
  شید-واپاشی، نور-واپاشی   
šidvâpâši, nurvâpâši

Fr.: photodésintégration   

The process by which atomic nuclei are broken apart into their constituent protons and neutrons by the impact of high energy gamma photons. Photodisintegration takes place during the core collapse phase of a → Type II supernova explosion.

photo- + → disintegration.

photodissociate
  شید-واهزیدن   
šid-vâhazidan

Fr.: photodissocier   

To dissociate a → molecule by → radiation. See also → photodissociation.

photo-; → dissociate.

photodissociation
  شید-واهزش، نور-واهزش   
šid-vâhazeš, nur-vâhazeš

Fr.: photodissociation   

The → dissociation of a → chemical compound by → radiation  → energy.

Verbal noun of → photodissociate; → -tion.

photodissociation region (PDR)
  ناحیه‌ی ِ شید-واهزش، ~ نور-واهزش   
nâhiye-ye šid-vâhazeš, ~ nur-vâhazeš

Fr.: région de photodissociation   

A neutral region at the boundary of a → molecular cloud created by the penetration of → far ultraviolet (FUV) radiation from associated stars. The FUV radiation (6 eV ≤ hν ≤ 13.6 eV) dissociates the molecules and heats the gas and dust. A warm, atomic → H I region is thus created and the chemistry and thermal balance of the region are determined by the penetrating FUV photons. The progressive absorption of FUV photons leads to the occurrence of transitions between atomic and molecular phases, such as H I/H2 and C II/C I/CO transitions. By extension, any neutral region where the physics is controlled by FUV photons can be called a PDR, as it is the case for → diffuse interstellar clouds or the edge of → circumstellar disks. The PDR concept was first studied by A. G. G. M. Tielens and D. Hollenbach (1985, ApJ 291, 722).

photodissociation + → region.

photoelectric
  شید-برقی، نور-برقی   
šid-barqi, nur-barqi

Fr.: photoélectrique   

Pertaining to electronic or other electrical effects that are due to the action of electromagnetic radiation, especially visible light.

photo- + → electric.

photoelectric current
  جریان ِ شید-برقی   
jarayân-e šid-barqi

Fr.: courant photoélectrique   

The current produced in an → photoelectric effect process when → photoelectrons are received at the positive electrode.

photoelectric; → current.

photoelectric effect
  ا ُسکر ِ شید-برقی، ~ نور-برقی   
oskar-e šid-barqi, ~ nur-barqi

Fr.: effet photoélectrique   

The process of release of electrically charged particles (usually → electrons) as a result of irradiation of matter by light or other → electromagnetic radiation. The classical electromagnetic theory was unable to account for the following characteristics of the phenomenon. Light below a certain threshold frequency, no matter how intense, will not cause any electrons to be emitted. Light above that frequency, even if it is not very intense, will always cause electrons to be ejected. The electrons are ejected after some nanoseconds, independently of the light intensity. The maximum kinetic energy of the emitted electrons is a function of the frequency and does not dependent on the intensity of the incident light. The classical theory could not explain how a train of light waves spread out over a large number of atoms could, in a very short time interval, concentrate enough energy to knock a single electron out of the metal. In 1905, based on Planck's idea of → quanta, Einstein proposed that light consisted of quanta (later called → photons); that a given source could emit and absorb radiant energy only in units which are all exactly equal to the radiation frequency multiplied by a constant (→ Planck's constant); and that a photon with a frequency over a certain threshold would have sufficient energy to eject a single electron. His photoelectric equation is descibed as (1/2)mu2 = hν - A, where m is the electron mass, u is the electron velocity, h is Planck's constant, ν is the frequency, and A the → work function, which represents the amount of work needed by electrons to get free of the surface. See also → photoelectron, → photoelectric current, → external photoelectric effect, → internal photoelectric effect.

photoelectric; → effect.

photoelectric heating
  گرمایش ِ شید-برقی   
garmâyeš-e šid-barqi

Fr.: chauffage photoélectrique   

A heating process occurring in → diffuse molecular clouds which is believed to be the main heating mechanism in cool → H I regions. Far-ultraviolet (FUV) photons, in the energy range 6 eV <hν < 13.6 eV, expel electrons from → interstellar dust grains and the excess → kinetic energy of the electrons is converted into gas → thermal energy through → collisions. The high energy limit corresponds to the cut-off in the → far-ultraviolet (FUV) radiation field caused by the hydrogen absorption (hν = 13.6 eV), while the low energy limit corresponds to the energy needed to free electrons from the grains (hν ~ 6 eV). In the cold neutral medium (Tkin≥ 200 K) photoelectric heating accounts for most of the heating, the → X-ray and → cosmic ray heating rates (→ cosmic-ray ionization) being more than an order of magnitude smaller. In a relatively dense neutral medium (nH≥ 100 cm-3), where a significant fraction of carbon is in the neutral form, carbon ionization becomes an important heating source, but it is still not comparable to the photoelectric effect. The heating rate cannot be directly measured, but it can be estimated through observations of the [C II] line emission, since this is believed to be the main → coolant in regions where the photoelectric heating is dominant (See, e.g., Juvela et al., 2003, arXiv:astro-ph/0302365).

photoelectric; → heating.

photoelectric magnitude
  بُرز ِ شید-سنجیک، ~ نور-سنجیک   
borz-e šidsanjik, ~ nursanjik

Fr.: magnitude photoélectrique   

The magnitude of an object as measured with a photoelectric photometer.

photoelectric; → magnitude.

photoelectric photometry
  شید-سنجی ِ شید-برقی   
šidsanji-e šidbarqi

Fr.: photométrie photoélectrique   

A photometry in which the magnitudes are obtained using a photoelectric photometer.

photoelectric; → photometry.

photoelectron
  شید-الکترون، نور-الکترون   
šid-elektron, nur-elektron

Fr.: photoélectron   

An electron emitted from an atom or molecule by an incident photon in the → photoelectric effect.

photo-; + → electron.

photoemissive effect
  اسکر ِ شید-گسیلی   
oskar-e šid-gosili

Fr.: effet photoémissif   

The emission of electrons as a result of incident radiation in the → photoelectric effect. Also called → external photoelectric effect.

photo- + → emissive; → effect.

photoevaporation
  شید-بخارش، نور-بخارش   
šidboxâreš, nurboxâreš

Fr.: photoévaporation   

A process going on in a molecular cloud surface whereby the surface material ionized by ultraviolet photons of neighboring stars is dissipated.

photo- + → evaporation.

photoexcitation
  شید-بر‌انگیزش   
šid-barangizeš

Fr.: photoexcitation   

The mechanism of raising an electron to higher energies by photon absorption, when the energy of the photon is too low to cause photoionization.

photo- + → excitation.

<< < -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 > >>