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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 690
dynamo model
  مدل ِ توانزا   
model-e tavânzâ

Fr.: modèle dynamo   

A theory for the generation of a star's or planet's magnetic field by the circulation of conducting fluids inside it. → solar dynamo.

dynamo; → model.

dynamo theory
  نگره‌ی ِ توانزا   
negare-ye tavânzâ

Fr.: théorie de la dynamo   

Branch of magnetohydrodynamics concerned with self-excitation of magnetic fields in any large rotating mass of conducting fluid in motion (usually turbulent). Self-exciting dynamo action is believed to account for magnetic fields at the planetary, stellar, and galactic scales.

dynamo; → theory.

dynamometer
  توان سنج   
tavânsanj (#)

Fr.: dynamomètre   

A device for measuring mechanical force; specifically, one that measures the output or driving torque of a rotating machine.

Dynamometer, from → dynamo + → -meter.

Tavânsanj, from tavân "power," → dynamics + -sanj, → -meter.

dyne
  دین   
din (#)

Fr.: dyne   

The centimeter-gram-second (cgs) unit of force (symbol dyn) that imparts an acceleration of 1 cm s-2 to a mass of 1 gram. 1 dyn = 10-5 → newton.

From Fr., from dynamis "power," → dynamics.

dynode
  دینود   
dinod (#)

Fr.: dynode   

An electrode that performs electron multiplication by means of secondary emission.

From dyn(a)- a combining form meaning "power," → dynamics + -ode a combining form meaning "way, road," used in the formation of compound words (anode; electrode), from Gk. hodos "way."

As above.

dys-
  دش-، دژ-   
doš- (#), dož- (#)

Fr.: dys-   

prefix meaning "bad, ill, abnormal."

From Gk. dys- "bad, hard, unlucky," cognate with O.Pers. duš-, Av. duž- (see below), Skt. dus- "bad, wrong, difficult, un-, -less," PIE *dus- "bad, ill."

Doš-, dož- "bad, ill, abnormal," from Mid.Pers. duž-, duš-, O.Pers. duš- (dušiyâr- "bad year, famine"), Av. duž-, duš- "bad" (duž-mainnyav- "evil-minded, enemy," Mod.Pers. došman "enemy"); PIE *dus-, as above.

Dysnomia (136199 Eris I)
  دوسنمیا   
Dusnomiya (#)

Fr.: Dysnomia   

A → satellite of the → dwarf planet → Eris.

Dysnomia in Gk. mythology is the daughter of Eris and the goddess of lawlessness.

Dyson shell
  پوسته‌ی ِ دایسون   
puste-ye Dyson

Fr.: couche de Dyson   

Dyson sphere.

Dyson; → shell.

Dyson sphere
  سپهر ِ دایسون   
sepehr-e Dyson

Fr.: sphère de Dyson   

A hypothetical structure built around a → star by an advanced → civilization to utilize most or all of the → energy radiated by their star. The idea of such a sphere was first formalized and popularized by theoretical physicist Freeman Dyson in 1960, though it was originally put forward by a 1945 science fiction novel. Dyson assumed that the power needs of → intelligent civilizations never stops increasing. He also proposed that searching for the existence of such structures might lead to the discovery of advanced civilizations elsewhere in the Galaxy. Sometimes referred to as a → Dyson shell or → megastructure.

Freeman John Dyson (1923-). His article, entitled "Search for Artificial Stellar Sources of Infrared Radiation," appeared in the 1960 issue of Science, 131 (3414), 1667-1668; → sphere.

DZ white dwarf
  سفید‌کوتوله‌ی ِ DZ   
sefid kutule-ye DZ

Fr.: naine blanche DZ   

A → white dwarf whose spectrum shows metal lines only; no H or He.

D short for → dwarf; Z a convention; → white.

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