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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

<< < -es -iv -ti 21- A r abe abs abs acc acc acc act act ada adi adu aff age alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg ari art ass ast ast ast atm ato att aur aut axi B r bac Bal Bar Bar Bay bec Ber Bet Bie bij bin bio bis bla bla blu blu bol Bor bou Bra bre bro Bug C-s cal Cam can car Car Cas cat cav cel cen cer Cha cha cha che cho cir cir cir 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 coo cor cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl dar dat daw de- Deb dec dec dee def deg del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis div dog Dop dou dra dua dus dwa dyn e-m ear ecl eco eff ein Ein elb ele ele ele ele Els emi emp ene enr env epi equ equ Eri est Euc eva evo exc exc exh exo exp exp ext ext f-n Fah fam fau fee Fer fib fil fin fir fix fle flu foc for for for fra fre fre fri fun fuz gal gal gal Gan gau GCN gen geo geo geo geo Gl glo gra gra gra gra gra gre gro GW1 hab hal han HAR haz hea hel hel Hen Her heu Hig Hil hol hop hor hou Hub Hum Hyd hyd hyd hyp hys ide ign ima imp imp inc inc ind ine inf inf inf inh INP ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jos Jun K2 Kep key kin Kol lag lam Lan lar las lav lea leg len lev lig lim lin lin lin lis lob loc log lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mea mee Men mer met met met mic mid Mil min Mir mix mod mod mol mon Mor mou mul muo mys nan nat nav nec Nep neu New New NGC nob nom non non nor not nuc nuc num Nyq obj obs obs oce oen OH omn opa ope opt opt opt orb ord Ori ort osc out ove oxy pal pan par Par par par pas pea Pen per per per per per pet pha pho pho pho phy pie Pit Pla pla pla pla ple Poi pol pol pol pol pop pos pos pow pre pre pre Pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua Qui rad rad rad rad rad rad ram ran rat rea rec rec rec red ref ref reg reg rel rel rem rep res res res ret rev rho Rie rim riv rol Ros rot rul S a Sah san Sat sca Sch Sch scr sec sec sec sei sel sem sep set sha she sho sid sig sil sim sin sit sky slu sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spl spr sta sta sta sta sta ste ste sti sto str str sub sub sub sug sun sup sup sup sup sur syl syn sys tal Tay tel ten ter tex the the the thi tho thu tid tim tod top tot tra tra tra tra tri tri tro tru tur twi Typ UFO ult unc uni uni uni upg ura uti val var vec vel ver ver vig vir vis voc von wak Was wav wax wea wei whi Wie win WN6 wom X-r yel you zer zod > >>

Number of Results: 12948 Search : far
Fermi-Dirac statistics
  آمار ِ فرمی-دیراک   
âmâr-e Fermi-Dirac (#)

Fr.: distribution Fermi-Dirac   

The statistical distribution of → fermions over the energy states for a system in → thermodynamic equilibrium. In other words, the probability that a given energy level be occupied by a fermion.

fermi, → Dirac function; → statistics.

Fermi-Pasta-Ulam problem
  پراسه‌ی ِ فرمی-پستا-اولام   
parâse-ye Fermi-Pasta-Ulam

Fr.: expérience Fermi-Pasta-Ulam   

A computer experiment that was aimed to study the → thermalization process of a → solid. In other words, the goal was to see whether there is an approximate → equipartition of energy in the system, which would mean that the motion is → chaotic. Using computer simulation, Fermi-Pasta-Ulam studied the behavior of a chain of 64 mass particles connected by → nonlinear springs. In fact, they were looking for a theoretical physics problem suitable for an investigation with one of the very first computers, the he MANIAC (Mathematical Analyzer, Numerical Integrator and Computer). They decided to study how a → crystal evolves toward → thermal equilibrium by simulating a chain of particles, linked by a quadratic interaction potential, but also by a weak nonlinear interaction. Fermi-Pasta-Ulam assumed that if the interaction in the chain were nonlinear, then an exchange of energy among the normal modes would occur, and this would bring forth the equipartition of energy, i.e. the thermalization. Contrary to expectations, the energy revealed no tendency toward equipartition. The system had a simple quasi-periodic behavior, and no → chaoticity was observed. This result, known as the Fermi-Pasta-Ulam paradox, shows that → nonlinearity is not enough to guarantee the equipartition of energy (see, e.g., Dauxois et al., 2005, Eur. J. Phys., 26, S3).

E. Fermi, J. Pasta, S. Ulam, 1955, Los Alamos report LA-1940; → problem.

fermion
  فرمیون   
fermion (#)

Fr.: fermion   

An elementary particle, such as → electron, → proton, or → neutron, having a half integral value of → spin. Fermions obey the → Pauli exclusion principle.

From Fermi → fermi + → -on.

ferric
  فریک   
ferrik

Fr.: ferrique   

Of or containing → iron, especially in the trivalent state. More specifically, iron with an → oxidation number of +3; also denoted iron(III) or Fe3+.

Ferric, from L. ferrum "iron," + → -ic.

ferric iron
  آهن ِ فریک   
âhan-e ferrik

Fr.: fer ferrique, fer trivalent   

Iron in a plus-3 → oxidation state. Ferric iron needs to share three electrons with an oxygen molecule to make the ion neutral.

ferric; → iron.

ferro-
  آهن-، فرو-   
âhan-, ferro-

Fr.: ferro-   

Indicating a property of → iron or the presence of iron.

Ferro-, variant ferri-, combining form of L. ferrum "iron."

Âhan-, → iron.

ferroelectric
  آهن‌برق‌مند   
âhanbarqmand

Fr.: ferroélectrique   

Characterized by the presence of a spontaneous → electric dipole while not exposed to an external electric field. → ferroelectricity.

ferro-; → electric.

ferroelectricity
  آهن‌برق‌مندی   
âhanbarqmandi

Fr.: ferroélectricité   

A property observed in certain materials characterized by the presence of a spontaneous electric polarization even in the absence of an external electric field. In the ferroelectric state the center of positive charge of the material does not coincide with the center of negative charge. This phenomenon is explained by spontaneous alignment of these permanent moments along the same direction. The term comes from the similarity with → ferromagnetism, but iron is not a ferroelectric. Ferroelectricity disappears above a critical temperature. Ferroelectric materials have been a fertile field for the study of → phase transitions.

ferro-; → electricity.

ferromagnet
  آهن‌مغنات   
âhanmeqnât

Fr.: ferro-aimant   

A ferroamagnetic substance, which possesses → ferromagnetism.

ferro-; → magnet.

ferromagnetic
  آهن‌مغناتی   
âhanmeqnâti

Fr.: ferromagnétique   

Relative to or characterized by → ferromagnetism.

ferro-; → magnetic.

ferromagnetism
  آهن‌مغنات‌مندی   
âhanmegnâtmandi

Fr.: ferromagnétisme   

A property of certain substances which are enormously more magnetic than any other known substance. Ferromagnetic substances, such as the chemical elements iron, nickel, cobalt, some of the rare earths, and ceratin alloys, achieve maximum → magnetization at relatively low magnetic field strengths. Their large → magnetic permeabilityies (greater than unity) vary with the strength of the applied field. When the temperature of a ferromagnet is increased the property vanishes gradually due to randomizing effects of thermal agitation. Beyond a definite temperature for each substance ( → Curie temperature) it ceases to behave as a ferromagnet and becomes a → paramagnet. Ferromagnetism is due to the alignment of the → magnetic moments of uncompensated electrons in the crystal lattice. Under the influence of an external magnetizing field, all of the uncompensated electrons line up with their → spins in the direction of the field. In contrast with paramagnetic substances, in which spins interact only with an external magnetic field, in ferromagnets the spins interact with each others, each of them trying to align the others in its own direction. This coupling gives rise to a spontaneous alignment of the moments over macroscopic regions called domains. The domains undergo further alignment when the substance is subjected to an applied field. Ferromagnets retain their magnetisation even when the external magnetic field has been removed. See also → antiferromagnetism ; → diamagnetism; → magnetism.

ferro-; → magnetism.

ferrous
  فرور   
fervar

Fr.: ferreux   

Of or containing → iron, especially in the bivalent state. More specifically, iron with → oxidation number of +2, denoted iron(II) or Fe2+.

From L. ferrum "iron," + -ous a suffix forming adjectives that have the general sense "possessing, full of" a given quality.

Fervar, from fer, loan from Fr., + -var adj. suffix.

ferrous iron
  آهن ِ فرور   
âhan-e fervar

Fr.: fer ferreux, fer bivalent   

Iron in a plus-2 → oxidation state.

ferrous; → iron.

fertile
  بارور   
bârvar (#)

Fr.: fertile   

Physics: (of nuclear material) Able to become → fissile by → neutron capture.

M.E., from M.Fr. fertil, from L. fertilis "bearing in abundance, fruitful, productive," from ferre "to bear," from PIE root *bher- "to carry," also "to bear children," cognate with Pers. bordan "to carry, bear," → refer.

Bârvar, literally "fruitful," from bâr "fruit; flower; load; charge" + possession suffix -var, related to bordan "to bear, carry," as above.

fertile isotope
  ایزوتوپ ِ بارور   
izotop-e bârvar

Fr.: isotope fertile   

An → isotope not itself → fissile but that is converted into a fissile isotope, either directly or after a short → decay process following absorption of a → neutron. Example: U-238 can capture a neutron to give U-239. U-239 then decays to Np-239 which in turn decays to fissile Pu-239. The most important fertile isotope is U-238. This is by far the most abundant isotope of natural uranium, making up 99.28%. The important transformation chain is: 92U238 + 0n193Np239 + β- (23.5 minutes) → 94Pu239 + β- (2.36 days).

fertile; → isotope .

Feynman diagram
  نمودار ِ فاینمن   
nemudâr-e Feynman

Fr.: diagramme de Feynman   

A schematic representation, in quantum electrodynamics and quantum chromodynamics, of the way elementary particles like electrons and protons interact with each other by exchanging photons. Use of Feynman diagrams can greatly reduce the amount of computation involved in calculating a rate or cross section of a physical process.

After the American physicist Richard P. Feynman (1918-1988), Nobel prize 1965; → diagram.

FHB star
  ستاره‌ی ِ FHB   
setâre-ye FHB

Fr.: étoile FHB   

Same as → field horizontal branch star.

field; → horizontal; → branch; → star.

fiber
  فیبر   
fibr (#)

Fr.: fibre   

optical fiber.

From Fr. fibre, from O.Fr. fibre, from L. fibra "a fiber, filament," of uncertain origin, perhaps related to L. filum "thread."

Fibr, loan from Fr., as above.

Fibonacci number
  عدد ِ فیبوناچی   
'adad-e Fibonacci

Fr.: nombre de Fobonacci   

One of the numbers in the → Fibonacci sequence.

Fibonacci sequence; → number.

Fibonacci sequence
  پی‌آیه‌ی ِ فیبوناچی   
peyâye-ye Fibonacci

Fr.: suite de Fibonacci   

An infinite sequence of integers, starting with 0 and 1, where each element is the sum of the two previous numbers. For example: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ... As the sequence develops, the ratio of the consecutive terms converges to the → golden ratio, about 1.618.

Leonardo Pisano Fibonacci (1170-1250), medieval Italian mathematician who wrote Liber abaci (1202; Book of the Abacus), the first European work on Indian and Arabian mathematics, which introduced "Arabic" numerals in Europe; → sequence.

<< < -es -iv -ti 21- A r abe abs abs acc acc acc act act ada adi adu aff age alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg ari art ass ast ast ast atm ato att aur aut axi B r bac Bal Bar Bar Bay bec Ber Bet Bie bij bin bio bis bla bla blu blu bol Bor bou Bra bre bro Bug C-s cal Cam can car Car Cas cat cav cel cen cer Cha cha cha che cho cir cir cir 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 coo cor cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl dar dat daw de- Deb dec dec dee def deg del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis div dog Dop dou dra dua dus dwa dyn e-m ear ecl eco eff ein Ein elb ele ele ele ele Els emi emp ene enr env epi equ equ Eri est Euc eva evo exc exc exh exo exp exp ext ext f-n Fah fam fau fee Fer fib fil fin fir fix fle flu foc for for for fra fre fre fri fun fuz gal gal gal Gan gau GCN gen geo geo geo geo Gl glo gra gra gra gra gra gre gro GW1 hab hal han HAR haz hea hel hel Hen Her heu Hig Hil hol hop hor hou Hub Hum Hyd hyd hyd hyp hys ide ign ima imp imp inc inc ind ine inf inf inf inh INP ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jos Jun K2 Kep key kin Kol lag lam Lan lar las lav lea leg len lev lig lim lin lin lin lis lob loc log lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mea mee Men mer met met met mic mid Mil min Mir mix mod mod mol mon Mor mou mul muo mys nan nat nav nec Nep neu New New NGC nob nom non non nor not nuc nuc num Nyq obj obs obs oce oen OH omn opa ope opt opt opt orb ord Ori ort osc out ove oxy pal pan par Par par par pas pea Pen per per per per per pet pha pho pho pho phy pie Pit Pla pla pla pla ple Poi pol pol pol pol pop pos pos pow pre pre pre Pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua Qui rad rad rad rad rad rad ram ran rat rea rec rec rec red ref ref reg reg rel rel rem rep res res res ret rev rho Rie rim riv rol Ros rot rul S a Sah san Sat sca Sch Sch scr sec sec sec sei sel sem sep set sha she sho sid sig sil sim sin sit sky slu sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spl spr sta sta sta sta sta ste ste sti sto str str sub sub sub sug sun sup sup sup sup sur syl syn sys tal Tay tel ten ter tex the the the thi tho thu tid tim tod top tot tra tra tra tra tri tri tro tru tur twi Typ UFO ult unc uni uni uni upg ura uti val var vec vel ver ver vig vir vis voc von wak Was wav wax wea wei whi Wie win WN6 wom X-r yel you zer zod > >>