An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 160 Search : and
Huggins band
  باند ِ هاگینس   
bând-e Huggins

Fr.: bande de Huggins   

A band in the → absorption spectrum of → ozone (O3) extending in the → ultraviolet from 310 nm to 370 nm. It is located at the red end of the strong → Hartley band.

W. Huggins and M. Huggins, Proc. R. Soc. London 48, 216 (1890).

if and only if (iff)
  اگر و ایواز اگر، ~ ~ تنها ~   
agar va ivâz agar, ~ ~ tanhâ ~

Fr.: si et seulement si   

Logic, Math.: An → expression indicating that two → statements so connected are → necessary and sufficient conditions for one another. The corresponding logical symbols usually used are: ↔, ⇔, ≡, and iff.

if; → and; → only.


Fr.: incandescence   

State of glowing at high → temperature; white or bright-red → heat.

Quality, state noun from → incandescent.

foruzandé (#)

Fr.: incandescent   

1) (Of light) produced by → incandescence.
2) Glowing or → white with → heat.
3) Intensely → bright; brilliant (

From Fr., from L. incandescent-, incandescens, p.p. of incandescere "to become hot," from → in- + candescere "to become hot," from candere "to glow."

Foruzandé, agent noun and verbal adj. from foruzidan, → glow.

incandescent lamp
  لامپ ِ فروزنده   
lâmp-e foruzandé (#)

Fr.: lampe à incandescence   

Electric lamp in which light is produced by the heating effect of a → metal  → filament.

incandescent; → lamp.

independent random variables
  ورتنده‌های ِ کاتوره‌ی ِ ناوابسته   
vatandehâ-ye kâture-ye nâvâbasté

Fr.: variables aléatoires indépendantes   

Statistics: Two random variables X and Y if and only if the value of X has no influence on the value of Y and vice versa.

dependent; → random; → variable.


Fr.: integrand   

The function which is being integrated in a given integral.

From L. integrandum, noun use of neuter of integrandus, gerundive of integrare, → integrate.

Dorostâlân, pr.p. of dorostâlidan, → integrate.

  آداک، آبخوست، جزیره، تمب   
âdâk (#), âbxost (#), jaziré (#), tomb (#)

Fr.: île   

A tract of land completely surrounded by water, and not large enough to be called a → continent (

M.E. iland, from O.E. igland "island," from ieg "island;" PIE *akwa- "water," cf. Pers. âb, → water, + → land.

Âdâk, âdak, adak "island" (Dehxodâ), probably from Proto-Ir. *āpdaka- "placed in water," from *âp-, → water, cf. Pers. âb, + *da- "to place, put," cf. Pers. dâdan "to give," → thesis, + suffix *-ka.
Âbxost, ultimately from āpxvasta-, literally "stricken/pounded by water," from *āp-, → water, + *xvasta-, from Proto-Ir. *huah- "to strike, to thresh;" cf. Av. (paiti)xvanh- "to thresh;" Mid.Pers. xwastan "to tread, trample, thresh;" Mod.Pers. xvast "trampled, beaten," âbxun "island," šabixun "night attack;" Kurd. xistin, xin-, xa- "to strike, to beat;" Hamedâni xostan/xus-, Esfahâni xosan "to throw."
Jaziré loan from Ar. jazirah.
Tomb "island" in Iranian Hormozgâni dialects.

island universe
  گیتی-آداک، گیتی-جزیره   
giti-âdâk, giti-jaziré

Fr.: univers-île   

The hypothesis first put forward by Immanuel Kant (1724-1804) according to which the objects termed "spiral nebulae" were stellar systems comparable to our own → Milky Way galaxy. At the end of the 18th century, William Herschel (1738-1822) using his giant reflectors discovered thousands of such nebulae. However, in spite of advances in observations it was never possible to prove Kant's idea until the second decade of the twentieth century. The observations using the Mount Wilson 2.50m (100 inch) telescope allowed Edwin Hubble in 1924 to firmly establish that the "spiral nebulae" were unquestionably extragalactic.

The term "island Universe" was first introduced by the German Alexander von Humboldt in 1850; → island; → Universe.

  خشکی، زمین   
xoški (#), zamin (#)

Fr.: terre   

Any part of the earth's surface not covered by a body of water.

M.E., from O.E. land, lond, "ground, soil, territory;" PIE base *lendh- "land, heath" (cf. O.N., O.Fris. Du., Ger., Goth. land; O.Ir. land; Welsh llan "enclosure, church," Breton lann "heath," source of Fr. lande; O.C.S. ledina "waste land, heath," Czech lada "fallow land").

Xoški, from xošk, → dry, + noun suffix -i; zamin "land, → earth."

land breeze
  نسیم ِ خشکی   
nasim-e xoški (#)

Fr.: brise de terre   

A coastal breeze blowing from land to sea after sunset, caused by the temperature difference when the sea surface is warmer than the adjacent land. The warmer air above the water continues to rise, and cooler air from over the land replaces it, creating a breeze.

Land, → lander; → breeze.

Xoški "land," from xošk "dry;" Mid.Pers. xušk "dry;" O.Pers. uška- "mainland;" Av. huška- "dry;" cf. Skt. śuska- "dry, dried out;" Gk. auos "dry, dried up;" O.E. sēar "dried up, withered;" Lith. sausas "dry, barren."

Landau damping
  میرایی ِ لانداؤ   
mirâyi-ye Landau

Fr.: amortissement de Landau   

The process wherein a → plasma gains energy at the expense of the → Langmuir wave. In the presence of the → Landau resonance, the particles in resonance moving slightly faster than the wave lose energy, while those moving slightly slower will gain energy. Since the Maxwellian distribution is decreasing with velocity, in a Maxwellian plasma, near the Landau resonance, there are more particles at lower velocities than at higher velocities. Also called collisionless damping.

Lev Landau (1908-1968), a prominent Soviet physicist, 1962 Nobel Prize in Physics for his development of a mathematical theory of → superfluidity; → damping.

Landau level
  تراز ِ لانداؤ   
tarâz-e Landau

Fr.: niveau de Landau   

The → energy level which can be occupied by a → free electron in a → magnetic field.

Landau damping; → level.

Landau resonance
  باز‌آوایی ِ لانداؤ   
bâzâvâyi-ye Landau

Fr.: résonance de Landau   

For parallel propagating → electrostatic waves in a → plasma, the → resonance which occurs when the particle velocity equals the parallel phase velocity of the wave.

Landau damping; → damping.

Landé factor
  کروند ِ لانده   
karvand-e Landé

Fr.: facteur de Landé   

The constant of proportionality relating the separations of lines of successive pairs of adjacent components of the levels of a spectral multiplet to the larger of the two J-values for the respective pairs. The interval between two successive components J and J + 1 is proportional to J + 1.

After Alfred Landé (1888-1976), a German-American physicist, known for his contributions to quantum theory; → facteur.


Fr.: atterrisseur   

A → space probe designed to land on a → planet or other solid → celestial body.

land; → -er.

left-hand rule
  رزن ِ دست ِ چپ   
razan-e dast-e cap

Fr.: règle de la main gauche   

See → Fleming's rules.

left; → hand; → rule.

  چپال، چپدست   
capâl (#) , capdast (#)

Fr.: gaucher   

Using the left hand with greater ease than the right.

left; → hand + -ed.

Capâl, from cap, → left, + -al, → -al. Capdast, with dast, → hand.

local standard of rest
  استانده‌ی ِ محلی ِ آرم   
estânde-ye mahali-ye âram

Fr.: standard local de repos   

A frame of reference that turns around the Galactic center at a velocity and a distance which are the mean values for the stars in the solar neighborhood. In this reference system the stars belonging to the solar neighborhood are statistically at rest. The orbital velocity of the Local Standard of Rest around the Galaxy is about 220 km/sec.

local; → standard; → rest.

lunar highland
  کوهسار ِ مانگی   
kuhsâr-e mângi

Fr.: hauts plateaux lunaires   

A light color area on the → Moon, as contrasted with → lunar maria. Also called terra.

lunar; → highland.

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