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: 96 Search : wave
microwave radiation
  تابش ِ ریزموج   
tâbeš-e rizmowj (#)

Fr.: rayonnement micro-onde   

Electromagnetic radiation carried by → microwaves.

microwave; → radiation.

millimeter wave
  موج ِ میلی‌متری   
mowj-e milimetri (#)

Fr.: onde millimétrique   

Microwaves with wavelengths between 1 and 10 millimeter, corresponding to frequencies between 300 GHz to 30 GHz. → millimeter-wave astronomy.

milli-; → meter; → wave.

millimeter-wave astronomy
  اخترشناسی ِ موج‌های ِ میلی‌متری   
axtaršenâsi-ye mowjhâ-ye milimetri (#)

Fr.: astronomie millimétrique   

That part of radio astronomy which uses electromagnetic waves in the range 1-10 millimeter to study various components of the Universe, in particular the chemistry of interstellar matter.

millimeter wave; → astronomy.

modulated wave
  موج ِ دگر‌آهنگیده   
mowj-e degarâhangidé (#)

Fr.: onde modulée   

A combination of two or more waves resulting in the production of frequencies not present in the original waves, the new frequencies being usually the sums and differences of integral multiples of the frequencies in the original waves.
A wave which varies in some characteristic in accordance with the variations of a modulating signal. Compare continuous wave. See modulation

Modulated, p.p. of → modulate; → wave.

Moreton wave
  موج ِ مورتون   
mowj-e Moreton

Fr.: onde de Moreton   

A large-scale → shock wave observed in Hα on the Sun's → chromosphere that is generated by the impact of a → solar flare. Moreton waves expand outward at about 1,000 km/s, and may travel for several hundred thousand kilometers. They are accompanied by meter-wave radio bursts.

Named after the American astronomer Gail E. Moreton (1960, A.J. 65, 494); → wave.

neutral wave
  موج ِ نتار   
mowj-e natâr

Fr.: onde neutre   

Same as → neutral mode.

neutral; → wave.

P-wave
  موج ِ P   
mowj-e P

Fr.: onde P   

compressional wave.

P, referring to → pressure; → wave.

peak wavelength
  موج-طول ِ ستیغ   
mowj-tul-e setiq

Fr.: longueur d'onde pic   

The wavelength at which the radiant intensity of a source is maximum.

peak; → wavelength.

periodic wave
  موج ِ دوره‌ای   
mowj-e dowre-yi

Fr.: onde périodique   

An oscillatory motion in which each point is repeatedly displaced at equal time intervals.

periodic + → wave.

plane wave
  موج ِ تخت   
mowj-e taxt (#)

Fr.: onde plane   

A wave whose wavefronts of constant phase are infinite parallel planes normal to the direction of propagation.

plane; → wave.

quarter-wave plate
  تیغه‌ی ِ چارک-موج   
tiqe-ye cârak-mowj

Fr.: lame quart d'onde   

A plate of doubly refracting material cut parallel to the optic axis of the crystal and of such a thickness that a phase difference of 90° is introduced between the ordinary and extraordinary rays for light of a particular wavelength. → half-wave plate.

quarter; → wave; → plate.

radio wave
  موج ِ رادیویی   
mowj-e râdioyi (#)

Fr.: ondes radio   

The → electromagnetic radiation with the longest → wavelengths (and lowest energies), ranging from 0.3 mm to several km. Radio waves form a very broad category, which includes the → submillimeter waves (with a wavelength of 0.3-1 mm) and → microwave regions (1 mm to several cm).

radio; → wave.

radio wavelength
  موج-طول ِ رادیویی   
mowjtul-e râdioyi

Fr.: longueur d'onde radio   

The → electromagnetic radiation with a wavelength ranging from 1 mm to several 100 km. See so → radio wave.

radio; → wavelength.

rarefaction wave
  موج ِ آلرش   
mowj-e âlareš

Fr.: onde de raréfaction   

A pressure wave in a fluid generated by rarefaction. It travels in the opposite direction to that of a shock wave in the medium.

rarefaction; → wave.

retarded wave
  موج ِ دیررس   
mowj-e dirras

Fr.: onde retardée   

An ordinary electromagnetic wave that goes forward with time. → Maxwell's equations are indifferent to the distinction between past and future. It is therefore permissible for the electromagnetic waves to go backward in time. Forward-in-time waves are called retarded, as they arrive after they are sent by the transmitter. Backward-in-time waves are called → advanced wave.

Retarded, adj. of → retard; → wavel.

Rossby wave
  موج ِ روسبی   
mowj-e Rossby

Fr.: onde de Rossby   

A wave on a uniform current in a two-dimensional non-divergent fluid system, rotating with varying angular speed about the local vertical.

Rossby number; → wave.

S-wave
  موج ِ S   
mowj-e S

Fr.: onde S   

shear wave.

S, referring to → shear; → wave.

scalar wave
  موج ِ مرپلی   
mowj-e marpeli

Fr.: onde scalaire   

In theories of gravitation, a kind of → gravitational wave, transversal and/or longitudinal, characterized by → spin zero.

scalar; → wave.

seismic wave
  موج ِ لرزه‌ای   
mowj-e laez-yi (#)

Fr.: onde sismique   

An → elastic wave generated in the → Earth by an → impulse such as an → earthquake or an → explosion. Seismic waves may travel either along or near the Earth's surface or through the Earth's interior.

seismic; → wave.

Shack-Hartmann wavefront sensor
  حسگر ِ پیشان ِ موج ِ شک-هارتمان   
hessgar-e pišân-e mowj-e Shack-Hartmann

Fr.: analyseur de front d'onde   

An optical device, a modern version of the → Hartmann test, used for analyzing the wavefront of light. Theses sensors can be used to characterize the performance of optical systems. Moreover, they are increasingly used in real-time applications, such as → adaptive optics to remove the wavefront distortion before creating an image. It consists of a microlens array placed in front of a CCD array. A planar wavefront that is transmitted through a microlens array and imaged on the CCD array will form a regular pattern of bright spots. If, however, the wavefront is distorted, the light imaged on the CCD will consist of some regularly spaced spots mixed with displaced spots and missing spots. This information is used to calculate the shape of the wavefront that was incident on the microlens array.

Named after the German astronomer Johannes Hartmann (1865-1936), who first developed the method, and R. V. Shack, who in the late 1960s replaced the screen by a microlens array; → wavefront; → sensor.

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