An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -me Edd ion phy Tis > >>

Number of Results: 90 Search : meter
physical parameter
  پارامون ِ فیزیکی   
pârâmun-e fiziki

Fr.: paramètre physique   

Any of a set of physical properties whose values determine the characteristics or behavior of a system; for example, → mass, → size, → temperature, → luminosity, etc.

physical; → parameter.


Fr.: potentiomètre   

An instrument for measuring electrical quantities by balancing an unknown potential difference against a known potential difference.

From potenti(al), → potential + -o + → -meter.


Fr.: pyrhéliomètre   

General term for the class of → actinometers that measure the intensity of solar radiation received on the surface of the Earth. It functions by converting the heat of the sunlight into a voltage using a device called a thermopile, and a recording voltmeter.

From pyr-, from → pyro- + → heliometer.

âzarsanj (#)

Fr.: pyromètre   

A device used for measuring high temperatures. By comparing a source whose temperature is to be measured to a standardized source of illumination, it determines the temperature of the former source.

pyro- + → -meter.

radio interferometer
  اندرزنش‌سنج ِ رادیویی   
andarzanešsanj-e râdioyi

Fr.: interféromètre radio   

An → interferometer designed for radio frequencies.

radio; → interferometer.

tâbeš-sanj (#)

Fr.: radiomètre   

An instrument that measures the intensity of radiant energy.

radio; → -meter.

reddening parameter
  پارامون ِ سرخش   
pârâmun-e sorxeš

Fr.: paramètre de rougissement   

A dimensionless quantity characterizing the → interstellar extinction, defined by the total-to-selective extinction ratio: RV = AV/E(B-V). The typical value found for the reddening parameter in the Milky Way is RV ~ 3.1, but it is known to vary from one line of sight to another, from values as 2 to as large as 6. Very large → dust grains would produce extinction with RV → ∞.

reddening; → parameter.

Rossby parameter
  پارامون ِ روسبی   
pârâmun-e Rossby

Fr.: paramètre de Rossby   

The northward variation of the Coriolis parameter, arising from the sphericity of the Earth.

Rossby number; → parameter.


Fr.: demi-diamètre   

The angle at the observer subtended by the equatorial radius of the Sun, Moon, or a planet.

semi-; → diameter.

size parameter
  پارامون ِ اندازه   
pârâmun-e andâzé

Fr.: paramètre de taille   

A quantity that defines the type of → scattering.

size; → parameter.

slope parameter
  پارامون ِ شیب   
pârâmun-e šib

Fr.: paramètre de pente   

In a → power-law distribution or → regression, the → exponent that represents the effect of the → independent variable, x, on the → dependent variable, y. X has no association with y if the slope parameter = 0 and x has strong association with y if the slope parameter is large.

slope; → parameter.


Fr.: spectromètre   

1) A spectrograph in which the spectrum is recorded by electronic means so that wavelength, intensity, etc. can be measured.
2) An instrument for determining the distribution of energies in a beam of particles.

spectro-; → -meter.


Fr.: spectrophotomètre   

An instrument designed to measure the intensity of a particular spectral line or a series of spectral lines.

spectro-; → photometer.

Square Kilometer Array (SKA)

Fr.: SKA   

An international project to construct a highly sensitive radio interferometer array operating between 0.15 and 20 GHz with an effective collecting area of one square kilometer. The number of individual telescopes will be 2000 to 3000. SKA will have a sensitivity 100 times higher than that of today's best radio telescopes and an angular resolution < 0.1 arcsec at 1.4 GHz. The site will be selected in 2012 and early science with Phase 1 is scheduled for from 2016 on. See also the SKA homepage.

square; → kilometer; → array.

Stokes parameters
  پارامون‌های ِ استوکس   
pârâmunhâ-ye Stokes

Fr.: paramètres de Stokes   

Four parameters which are needed to fully describe the → polarization state of → electromagnetic radiation. They involve the maximum and minimum intensity, the ellipticity, and the direction of polarization. The four Stokes parameters are traditionally defined as follows:
I ≡ total intensity.
Q ≡ I0 - I90 = difference in intensities between → horizontal and → vertical  → linearly polarized components.
U ≡ I+45 - I-45 = difference in intensities between linearly polarized components oriented at +45° and -45° (or 135°).
V ≡ Ircp - Ilcp = difference in intensities between right and left → circularly polarized polarized components.

Stokes; → parameter.


Fr.: sub-millimétrique   

Of or pertaining to scales smaller than millimeter.

sub-; → millimeter.

submillimeter astronomy
  اخترشناسی ِ زیر-میلیمتری   
axtaršenâsi-ye zir-milimetri

Fr.: astronomie sub-millimétrique   

The study of astronomical objects with → submillimeter waves. As with millimeter-wave astronomy, this part of the spectrum is rich in lines emitted by interstellar molecules and dust.

submillimeter; → astronomy.

submillimeter galaxy (SMG)
  کهکشان ِ زیر-میلیمتری   
kahkešân-e zir-milimetri

Fr.: galaxie sub-millimétrique   

A member of an extremely luminous population of → high-redshift galaxies which are detected in → submillimeter waves (→ flux density at 850 μm ≥ 3 - 5 mJy). SMGs are powered primarily by star formation rather than an → active galactic nucleus (AGN). Because of their high → dust content, these galaxies emit almost all of their luminosity in the infrared, with a → bolometric luminosity ranging from 1012-1013 → solar luminosities. As such, SMGs resemble → ultraluminous infrared galaxies (ULIRGs), which are almost exclusively → merging galaxies. Indeed, many observations support a → merger origin for SMGs (see, e.g. C.C. Hayward et al. 2011 and references therein, astro-ph/1101.0002).

submillimeter; → galaxy.

submillimeter radiation
  تابش ِ زیر-میلیمتری   
tâbeš-e zir-milimetri

Fr.: rayonnement sub-millimétrique   

That part of the → electromagnetic radiation with a → wavelength beyond 300 → microns.

submillimeter; → radiation.

submillimeter wave
  موج ِ زیر-میلیمتری   
mowj-e zir-milimetri

Fr.: onde sub-millimétrique   

An electromagnetic wave having wavelengths less than one millimeter (frequencies greater than 300 gigahertz).

millimeter; → wave.

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