An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -ge Gal Gal gal Gan gau Gei gen geo geo geo gia gla gol gra gra gra gra Gre Gru > >>

Number of Results: 399

Fr.: galvanisation   

The coating of steel or iron with → zinc, either by immersion in a bath of molten zinc or by electrolytic deposition from a solution of zinc sulfate, to give protection against corrosion.

Verbal noun of → galvanize.


Fr.: galvaniser   

1) To coat a metal with → zinc by dipping into molten zinc or by electrolytic deposition.
2) To stimulate by application of an electric current.

From Fr. galvaniser, from galvanisme, → galvanism.

Gâlvânidan, from Gâlvâni, → galvanism, + -idan, → -ize.


Fr.: galvano-   

A prefix denoting galvanic or galvanism in compound words, such as → galvanometer, → galvanoplasty.

Galvano-, from → galvanism.


Fr.: galvanomètre   

An instrument for measuring or detecting small → direct currents, usually by the mechanical reaction between the magnetic field of the current and that of a magnet.

galvano- + → -meter.


Fr.: galvanoplastie   

A process used for covering an object with a thin layer of metal by electrochemical means.

galvano- + -plasty a suffix meaning "molding, formation, surgical repair, plastic surgery," from Gk. -plastia, from plastos "molded, formed," from plassein "to mold."

Gâlvânopuši, from gâlvâno-, → galvano-, + puši "covering, coating," from pušidan "to cover; to put on" (Mid.Pers. pôšidan, pôš- "to cover; to wear;" cf. Mid.Pers. pôst; Mod.Pers. pust "skin, hide;" O.Pers. pavastā- "thin clay envelope used to protect unbaked clay tablets;" Skt. pavásta- "cover," Proto-Indo-Iranian *pauastā- "cloth").

bâzi (#)

Fr.: jeu   

1) An amusement or pastime.
2) The material or equipment used in playing certain games.
3) A competitive activity involving skill, chance, or endurance on the part of two or more persons who play according to a set of rules, usually for their own amusement or for that of spectators (

M.E. gamen. O.E. gaman "game, joy, fun, amusement;" cf. O.Fris. game "joy, glee," O.N. gaman, O.H.G. gaman "sport, merriment," D. gamen, Sw. gamman.

Bâzi, from Mid.Pers. wâzig "game, play," related to bâzidan "to play," bâxtan/bâz- "to loose (in game);" Proto-Ir. *uāz- "to play, contend;" cf. Skt. vāja- "contest, war, gain, reward" (Cheung 2007).


Fr.: gamma   

1) The third letter of the Greek alphabet (γ, Γ).
2) Symbol used to denote the ratio of the principal specific heats CP/CV of a gas, where CP is the specific heat at constant pressure and CV that measured at constant volume.
3) Unit of magnetic field intensity, equal to 10-5 gauss.
4) The distance of the Moon's shadow axis from Earth's center in units of equatorial Earth radii. It is defined at the instant of → greatest eclipse when its absolute value is at a minimum (F. Espenak, NASA).

The third letter of the Gk. alphabet, from Gk. gamma, from Phoenician gimel.

Gamma Cephei
  گاما کفءوس   
gâmâ Kefeus

Fr.: γ Cephei   

A bright, third → magnitude (3.22) → giant star of → spectral type K1, also called → Errai, HR 8974, HIP 116727, and HD 222404. γCephei has a → surface temperature of 4920 K a mass of 1.40 Msun, a → luminosity 10.6 solar, and a radius 4.8 solar. Its distance is estimated to be 45 → light-years. γ Cephei will become the → Pole Star in about 2,000 years. γ Cephei has a low mass → companion (B), a main → main sequence star of spectral type M4 V with a mass of 0.4 Msun. It orbits the → primary star every 67.5 years. An → extrasolar planet. (γ Cephe b) has been discovered orbiting the main star.

Gamma, as in → Bayer designation; → Cepheus.

Gamma Cygni
  گاما ماکیان   
gâmâ Mâkiyân

Fr.: γ Cygni   

The star → Sadr.

Gk. letter → gamma; Cygni, genitive of → Cygnus.

gamma decay
  تباهی ِ گاما   
tabâhi-ye gâmâ (#)

Fr.: désintégration gamma   

A type of → radioactivity in which some unstable atomic nuclei dissipate excess energy by a spontaneous electromagnetic process, usually accompanied by → alpha decay or → beta decay.

gamma; → decay.

gamma mechanism
  ساز-و-کار ِ گاما   
sâzokâr-e γ

Fr.: mécanisme γ   

A process which reinforces the → kappa mechanism in a → partial ionization zone. Because the temperature in the partial ionization zone is lower than in the adjacent stellar layers, heat tends to flow into the zone during compression, prompting further ionization.

γ, after the smaller ratio of → specific heats caused by the increased values of Cp and Cv; → mechanism.

gamma rays
  پرتوها‌ی ِ گاما   
partowhâ-ye gâmmâ (#)

Fr.: rayons gamma   

An → electromagnetic wave with a typical → wavelength less than 10-2Å (10-12 m), corresponding to frequencies above 1019 Hz and photon energies above 100 → keV.

gamma; → ray.

gamma-ray astronomy
  اخترشناسی ِ پرتوها‌ی ِ گاما   
axtaršenâsi-ye partowhâ-ye gâmmâ (#)

Fr.: astronomie en rayons gamma   

The study of → gamma rays from → extraterrestrial → sources, especially → gamma-ray bursts.

gamma ray; → astronomy.

gamma-ray burst (GRB)
  بلک ِ پرتوها‌ی ِ گاما   
belk-e partowhâ-ye gâmmâ

Fr.: sursaut de rayons gamma   

Intense discharges of soft gamma rays of unknown origin, which range in duration from tenth of a second to tens of seconds and occur from sources widely distributed over the sky. The radio wave afterglow from the burst can last more than a year, making long-term observations of the enigmatic sources possible.

gamma rays; → burst.

gamma-ray burster
  بلک‌گر ِ پرتو ِ گاما   
belkvar-e partow-e gâmmâ

Fr.: source à sursaut gamma   

The → object or → phenomenon at the origin of a → gamma-ray burst.

gamma ray; → burster.

gamma-ray source
  خن ِ پرتوهای ِ گاما   
xan-e partowhâ-ye gâmma

Fr.: source de rayons gamma   

1) An astronomical object that emits → gamma rays.
2) A radioactive material that emits gamma rays in a form that can be used in medical imaging.

gamma ray; → source.

Gamma2 Velorum
  گاما۲ بادبان   
gâmâ2 bâdbân

Fr.: γ2 Velorum   

The closest → Wolf-Rayet star, located at 336 → parsecs. Also known as HR 3207, HD 68273, and WR 111. γ2 Velorum is composed of a → WC8 component in a → close binary system with an → O star in a 78.5 day orbit (see, e.g., Lamberts et al., 2017, arXiv: 1701.01124).

Gamma, as in → Bayer designation; Velorum, genitive of → Vela.

Gamow barrier
  ورغه‌ی ِ گاموف   
varqe-ye Gâmof (#)

Fr.: barrière de Gamow   

In nuclear physics, a potential barrier near the surface of the nucleus that inhibits the release of alpha particles.

Gamow, after George Gamow (originally Georgiy Antonovich Gamov), the Ukrainian born theoretical physicist and cosmologist, who discovered quantum tunneling; → barrier.

Gamow condition
  بوتار ِ گاموف   
butâr-e Gamow

Fr.: condition de Gamow   

The constraint on the → baryon number density at T ~ 109 K in the early → expanding Universe. Gamow recognized that a key to the element buildup is the reaction n + p ↔ d + γ. Deuterium needs to be produced in sufficient abundance for higher elements to form, but if all → neutrons are immediately locked up into → deuterium, no higher elements can form either. The Gamow condition is expressed by nb<σv>t ~ 1, where nb is the baryon number density, σ is the cross section for the reaction at relative → velocity v, and t the expansion time-scale for the → Universe. This means that the time-scale for the above reaction is comparable to the expansion time. From this condition the baryon number density at the start of element buildup is found to be nb ~ (σvt)-1 ~ 1018 cm-3 at T = 109 K (P. J. E. Peebles, 2013, Discovery of the Hot Big Bang: What happened in 1948, arXiv.1310.2146).

Gamow barrier; → condition.

Gamow peak
  ستیغ ِ گاموف   
setiq-e Gâmof

Fr.: pic de Gamow   

In nuclear fusion, the product of the Maxwell-Boltzmann distribution with the tunnelling probability of the nuclei through their Coulomb barrier. This is the energy region where the reaction is more likely to take place: at higher energies, the number of particles becomes insignificant while at lower energies the tunnelling through the Coulomb barrier makes the reaction improbable.

Gamow barrier; → peak.

<< < -ge Gal Gal gal Gan gau Gei gen geo geo geo gia gla gol gra gra gra gra Gre Gru > >>