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

A pair of dissimilar conductors, commonly metals, in electrical contact.

→ galvanism; → couple.

The direct electric current that flows between metals or conductive nonmetals in a → galvanic couple.

→ galvanism; → current.

1) The production of electricity from a chemical reaction.
2) The therapeutic application of electricity to the human body.

From Fr. galvanisme, after Luigi Galvani (1737-1798), the Italian physiologist, who demonstrated (1790) muscular action due to contact with dissimilar metals.

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.

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.

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

Galvano-, from → galvanism.

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.

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").

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 (Dictionary.com).

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).

1) The third letter of the Greek alphabet (γ, Γ).
2) Symbol used to denote the ratio of the principal specific heats C_P/C_V of a gas, where C_P is the specific heat at constant pressure and C_V 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.

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.

The star → Sadr.

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

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.

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 C_p and C_v; → mechanism.

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.

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

→ gamma ray; → astronomy.

An intense discharge of → gamma rays, 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 sources possible. The favored hypothesis is that they are produced by a relativistic jet created by the merger of two → compact objects (specifically two → neutron stars or a neutron star and a → black hole). Mergers of this kind are also expected to create significant quantities of neutron-rich radioactive species, whose decay should result in a faint → transient, known as a → kilonova, in the days following the burst. Indeed, it is speculated that this mechanism may be the predominant source of stable → r-process elements in the Universe. Recent calculations suggest that much of the kilonova energy should appear in the → near-infrared spectral range, because of the high optical opacity created by these heavy r-process elements (Tanvir et al., 2017, Nature 500, 547).

→ gamma rays; → burst.

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

→ gamma ray; → burster.

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.

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.