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 p abe abs abs aca acc acc acr act ada adh Adr aer AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara Arc ari Arr ash ass ast ast asy atm ato att aut ave axi Bab bal Bal bar bar bea Bek Bes bia Big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo cal cal can cap car Car cat cat CCD Cen cen CH cha cha che Che chr cir cir cit 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 con Cop Cor cor cor cos cos cou cou Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp opt opt orb ord ori ort osc out ove oxi pai pan par par par par pas pea pen per per per per Per per pha phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar ray rea rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>

Number of Results: 13048 Search : far
perturbation
  پرتورش   
partureš

Fr.: perturbation   

1) Any departure introduced into a steady state of a system. The magnitude is often assumed to be small so that the resulting terms in the dependent variables may be neglected. The term "perturbation" is therefore sometimes used as synonymous with "small perturbation."
2) Gravitational effect of a third body that causes an alteration in the orbit of a body going around its primary.
See also: → linear perturbation theory, → method of small perturbationsn → perturbation equation, → perturbation method, → primordial curvature perturbation, → scalar perturbation, → secular perturbation, → tensor perturbation, → vector perturbation.

Verbal noun of → perturb.

perturbation equation
  هموگش ِ پرتورش   
hamugeš-e partureš

Fr.: équation de perturbation   

Any equation governing the behavior of a → perturbation.

perturbation; → equation.

perturbation method
  روش ِ پرتورش   
raveš-e partureš

Fr.: méthode de perturbation   

Approximate method of solving a difficult problem if the equations to be solved depart only slightly from those of a problem already solved.

perturbation; → method.

perturber body
  جسم ِ پرتورنده   
jesm-e parturandé

Fr.: corps perturbateur   

A celestial body that causes a perturbation in the orbit of another body.

Agent noun of → perturb; → body.

peta-
  پتا-   
petâ- (#)

Fr.: péta-   

A prefix denoting 1015.

Of unknown origin.

petro-
  سنگ-   
sang- (#)

Fr.: petro-   

A combining form meaning "rock," "stone." Also, petri-, and petr- when before a vowel.

From Gk. petro-, combining form of petra "rock."

Sang "rock," → stone.

petroleum
  نفت   
naft (#)

Fr.: pétrole   

Natural mixture of liquid hydrocarbons and other organic compounds that include crude oil, refined products obtained from the processing of crude oil, and natural gas liquids.

M.L. petroleum literally "rock oil," from L. petra "rock," from Gk. → petro-, + oleum "oil."

Naft, from Mid.Pers. npt "moist, damp; naphtha," nmb "moisture," from which derives Mod.Pers. nam "humidity, moisture;" Av. napta- "moist," nabah- "cloud; sky;" cf. Skt. nábhas- "moisture, cloud, mist;" PIE base *nebh- "cloud, vapor, fog, moist, sky" (Gk. nephos "cloud, mass of clouds," nephele "cloud;" L. nebula "mist," nimbus "rainstorm, rain cloud;" O.H.G. nebul; Ger. Nebel "fog;" O.E. nifol "dark"). The link between "water, moisture" and "naphta" is suggested to be the natural gas or oil seepages surfacing through water. In fact many of the Zoroastrian fire-temples were located in areas which contained large petroleum leakages, such as those in Khuzestân and at Surakhany near Baku.

petrology
  سنگ‌شناسی   
sangšenâsi (#)

Fr.: pétrologie   

The branch of → geology that deals with → rocks: their classification, composition, structure, occurrence, and conditions of origin.

petro-; → -logy

peVatron
  پواترون   
peVatron

Fr.: peVatron   

An astrophysical source which accelerates → cosmic rays up to energies of several petaelectronvolts. For example, in the → Galactic center, cosmic ray → protons reach such energies. The source of such particles is a matter of research (→ HESS collaboration, 2016, Nature 531, 476).

PeVatron, from PeV (→ peta- + → electronvolt); + euphonic affix -a-; + → -tron.

Pfund series
  سری ِ پفوند   
seri-ye Pfund

Fr.: série de Pfund   

A series of lines in the infrared spectrum of atomic hydrogen whose representing transitions between the fifth energy level and higher levels.

After August Herman Pfund (1879-1949), an American physicist and spectroscopist; → series.

PG 1159 star
     
PG 1159

Fr.: PG 1159   

A member of the class of stars in transition between → post-AGB and → white dwarf stars, with temperatures as high as 200,000 K, mean mass about 0.6 Msun, and log g = 5.5-8. PG 1159 stars have no hydrogen or He I lines in their spectra, but do show weak He II lines and stronger lines of ionized carbon and oxygen. These stars are thought to be the exposed inner core of a star that has exploded as a → planetary nebula and is on its way to become a white dwarf. Also called → pre-degenerate star

Named after their prototype PG 1159-035, from the Palomar-Green Catalog of Ultraviolet Excess Stellar Objects (Green et al. 1986, ApJS 61, 305); → star.

pH
  پ-هاش، پی-اچ   
p-hâš, pi-ec

Fr.: potentiel hydrogène   

A → logarithmic measure of → hydrogen ion concentration, originally defined pH = log10 (1/[H+]), where [H+] is the concentration of hydrogen ions in → moles per liter of solution. The hydrogen ion concentration in pure water around room temperature is about 1.0 × 10-7 moles. Therefore, a pH of 7 is considered "neutral," because the concentration of hydrogen ions is exactly equal to the concentration of → hydroxide (OH-) ions produced by → dissociation of the → water. Increasing the concentration of hydrogen ions above 1.0 × 10-7 moles produces a solution with a pH of less than 7, and the solution is considered → acidic. Decreasing the concentration below 1.0 × 10-7 moles produces a solution with a pH above 7, and the solution is considered → alkaline or → basic. The neutral pH is different for each → solvent. For example, the concentration of hydrogen ions in pure ethanol is about 1.58 × 10-10 moles, so ethanol is neutral at pH 9.8. A solution with a pH of 8 would be considered acidic in ethanol, but basic in water.

From Ger. PH, introduced by Danish biochemist S.P.L. Sørensen (1868-1939) in 1909, from P, for Ger. Potenz "power, potency," and H, symbol of → hydrogen.

Phad (γ UMa)
  فخذ   
Faxez (#)

Fr.: Phecda   

A blue, → main sequence star of → apparent visual magnitude 2.44 and → spectral type A0 Ve located in → Ursa Major. Other designations: Phecda; Phekda; Phegda; Phekha; Phacd.

Phad, from Ar. al-Fakhidh (ad-Dubb) (الفخذ‌الدب) "the thigh (of the Bear)".

Faxez, from Ar., as above.

Phaeton
  فایتون   
Phaeton

Fr.: Phaéton   

A hypothetical → planet which once was postulated to have existed between the orbits of → Mars and → Jupiter and its destruction supposedly led to the formation of the → asteroid belt. The idea of such a hypothetical planet was first put forward by the German astronomer Heinrich Wilhelm Olbers (1758-1840).

In Greek mythology Phaeton was the sun god Helios. Phaeton tried to drive his father's solar chariot but crashed after almost setting fire to the whole earth.

pharynx
  حلق   
halq (#)

Fr.: pharynx   

The tube or cavity, with its surrounding membrane and muscles, that connects the mouth and nasal passages with the esophagus (Dictionary.com). → throat.

From Gk pharynx (genitive pharyngos) "windpipe, throat."

Halq, loan from Ar.

phase
  ۱، ۲) فاز؛ ۳) سیما   
1, 2) fâz; 3) simâ

Fr.: phase   

1) A particular stage or point in a course, development, or graph varying cyclically; the fractional part of the period through which the time has advanced, measured from some arbitrary origin. Phase is measured like an angle, when a complete cycle is equivalent to a phase of 360° (or 2π radians), or, sometimes, as a number between 0 and 1. Two or more waves of the same frequency are → in phase when their maxima and minima take place at the same moments. Otherwise, they are said to be → out of phase or that they have a → phase difference.
2) A state in which matter can exist, depending on temperature and pressure, e.g. the → solid, → liquid, → gaseous, and → plasma states.
3) A recurring form of the → Moon or a → planet seen in the sky. → lunar phase, → phases of Venus.
4) In a → binary star system, → orbital phase.

Mod.L. phases, plural of phasis, from Gk. phasis "appearance," from stem of phainein "to show, to make appear."

1) Fâz, loanword from Fr., as above.
2) Simâ "face, aspect, resemblance."

phase angle
  زاویه‌ی ِ فاز   
zâviye-ye fâz (#)

Fr.: angle de phase   

1) Physics: Of a → periodic wave, the number of suitable units of angular measure between a point on the wave and a reference point.
2) Astro.: For an object in the solar system, the angle "Sun-object-Earth" that is, the angle between the Sun and the observer as seen from the given object. It is 0° when the object is fully illuminated, 90° when the object is half-illuminated (like the Moon at first quarter and last quarter), and 180° when the object is between Earth and the Sun.
3) More generally, the angle between star light incident onto a related revolving object and the light reflected from the object to the observer (Earth).

phase; → angle.

phase curve
  خم ِ فاز   
xam-e fâz

Fr.: courbe de phase   

1) Astro.: A curve describing the → brightness of a reflecting → natural satellite as a function of its → phase angle.
2) Math.: A plot of the solution to a set of equations of motion in a phase space as a function of time.

phase; → curve.

phase delay
  درنگ ِ فاز   
derang-e fâz

Fr.: délai de phase   

The ratio of the phase shift of a sinusoidal signal in transmission through a system to the frequency of the signal.

phase; → delay.

phase diagram
  نمودار ِ فاز   
nemudâr-e fâz

Fr.: diagramme de phases   

A graph showing the equilibrium relationships between phases (such as vapor-liquid, liquid-solid) of a chemical compound, mixture of compounds, or solution.

phase; → diagram.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara Arc ari Arr ash ass ast ast asy atm ato att aut ave axi Bab bal Bal bar bar bea Bek Bes bia Big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo cal cal can cap car Car cat cat CCD Cen cen CH cha cha che Che chr cir cir cit 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 con Cop Cor cor cor cos cos cou cou Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp opt opt orb ord ori ort osc out ove oxi pai pan par par par par pas pea pen per per per per Per per pha phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar ray rea rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>