An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < D l dar dat DB dea dec dec dec def def deh Del den dep des det dev dia dif dif dig Dio Dir dis dis dis dis dis diu doc dop dou Dra dua dus dwa dyn > >>

Number of Results: 737
dynamical system
  راژمان ِ توانیک   
râžmân-e tavânik

Fr.: système dynamique   

A system composed of one or more entities in which one state develops into another state over the course of time.

dynamical; → system.

dynamical time
  زمان ِ توانیک   
zamân-e tavânik

Fr.: temps dynamique   

The independent variable in the theories which describe the motions of bodies in the solar system. The most widely used form of it, known as Terrestrial Time (TT) or Terrestrial Dynamical Time (TDT) uses a fundamental 86,400 Systeme Internationale seconds (one day) as its fundamental unit. → Terrestrial Time; → Terrestrial Dynamical Time; → Barycentric Dynamical Time.

dynamical; → time.

dynamical time scale
  مرپل ِ زمانی ِ توانیک   
marpel-e zamâni-ye tavânik

Fr.: échelle de temps dynamique   

1) The characteristic time it takes a protostellar cloud to collapse if the pressure supporting it against gravity were suddenly removed; also known as the → free-fall time.
2) → crossing time for a stellar system like a galaxy.

dynamical; → time-scale.

dynamical variable
  ورتنده‌ی ِ توانیک   
vartande-ye tavânik

Fr.: variable dynamique   

Mechanics: One of the variables used to describe a system in classical mechanics, such as coordinates (of a particle), components of velocity, momentum, angular momentum, and functions of these quantities.

dynamical; → variable.


Fr.: dynamique   

The branch of → mechanics that explains how particles and systems move under the influence of forces.

dynamic; → -ics.

tavânzâ (#)

Fr.: dynamo   

An electric generator, i.e. a machine that converts mechanical energy into electrical energy by virtue of the → electromagnetic induction.

From Ger. dynamoelektrischemaschine, coined (1867) by the German inventor Werner von Siemens (1816-1892), from Gk. dynamis "power," → dynamics.

Tavânzâ, from tavân "power," → dynamics + -zâ "generator," from zâdan "to give birth," Mid.Pers. zâtan, Av. zan- "to bear, give birth to a child, be born," infinitive zazâite, zâta- "born," cf. Skt. janati "begets, bears," L. gignere "to beget," PIE base *gen- "to give birth, beget."

dynamo effect
  اسکر ِ دینامو   
oskar-e dinâmo

Fr.: effet dynamo   

The generation of magnetic fields by movements within a → plasma, such as the → convective cores and → convective envelopes of stars. The magnetic field is intensified by the motion of the plasma in much the same way as in a dynamo. The generated magnetic field is not static, but evolves over time.

dynamo; → effect.

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.

  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.

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.

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.

  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)
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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