An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 83 Search : non
non-thermal filament (NTF)
  رشته‌ی ِ ناگرمایی   
rešte-ye nâgarmâyi

Fr.: filament non thermique   

Any of many long and slender structures visible in → radio continuum images of the inner hundred parsecs of the → Galactic Center. NTFs are typically tens of parsecs long and only a fraction of parsec wide. They may occur in isolation or in bundles, such as those comprising the linear portion of the prominent → radio Arc. Their → non-thermal spectrum and strong → linear polarization indicate → synchrotron radiation. The magnetic fields in the NTFs have been estimated from various means. Early estimates centered on the radio Arc, and focused on a comparison between the → magnetic pressure and the estimated → ram pressure from nearby → molecular cloud interactions, indicated magnetic field strengths as high as 1 mG (Morris and Yusef-Zadeh 1985). More recent observations, however, have pointed to significantly weaker magnetic fields among the population of NTFs. Synchrotron models of the radio spectrum imply equipartition magnetic fields between 50-200 μG. Theoretically, it has been challenging to understand the nature of these filaments that resemble extragalactic → radio jets but are not accompanied with any obvious source of acceleration of charged particles to high energy → relativistic energies. Although a number of detailed models have been considered, there is no consensus as to the origin of the NTFs. These models suggest that molecular and ionized gas clouds, mass-losing stars, → Galactic winds, magnetic activity of the → supermassive black hole at the Galactic center, and → lepton production due to → dark matter annihilation play a role in the processes that lead to the production of the NTFs (Linden et al. 2011, ApJ 741,95, and references therein). In most models, the magnetic field is strong and its global geometry in the central region of the Galaxy is considered to be → poloidal and static. However, some recent models have argued that the magnetic field is local and dynamic.

non-thermal; → filament.

non-thermal radiation
  تابش ِ ناگرمایی   
tâbeš-e nâgarmâyi (#)

Fr.: rayonnement non thermique   

The electromagnetic radiation whose characteristics do not depend on the temperature of the emitting source. In contrast to → thermal radiation, it has a different spectrum from that of → blackbody radiation. The three common types of non-thermal radiation in astronomy are: → synchrotron radiation, → bremsstrahlung radiation, and → maser  → stimulated emission.

non-thermal; → radiation.

non-thermal spectrum
  بیناب ِ ناگرمایی   
binâb-e nâgarmâyi

Fr.: spectre non thermique   

A radio emission with a negative → spectral index. In this type of emission the intensity of the emitted radiation increases with wavelength.

non-thermal; → spectrum.


Fr.: non zéro, non nul   

Not equal to zero.

non-; → zero.

non-zero polynomial
  بلنامین ِ نا-صفر   
bolnâmin-e nâ-sefr

Fr.: polynôme non nul   

A → polynomial that at least has one non-zero → coefficient. See also → zero polynomial.

non-zero; → polynomial.

noncoherent scattering
  پراکنش ِ ناهمدوس   
parâkaneš-e nâhamdus

Fr.: diffusion incohérente   

The absorption of a photon and its re-emission at a different frequency (in the observer's frame of reference) by scattering atoms.

non-; → coherent scattering.

noncollisional plasma
  پلاسمای ِ نا-همکوبشی   
pelâsmâ-ye nâ-hamkubeši

Fr.: plasma non-collisionnel:   

A plasma in which the → mean free path of the charged particles between two collisions is much larger than the size of the system containing the plasma.

non-; → collisional; → plasma.

nondimensional equation
  هموگش ِ ناوامونی   
hamugeš-e nâvâmuni

Fr.: équation non-dimensionnelle   

An equation that is independent of the units of measurement as it only involves nondimensional numbers, parameters, and variables.

non-; → dimensional; → equation.

nâtohi (#)

Fr.: non vide   

Describing something that is partially or totally occupied.

non; → empty.

nonempty set
  هنگرد ِ ناتهی   
hangard-e nâtohi

Fr.: ensemble non vide   

A set containing at least → one → element.

nonempty; → set.

  ناهستومندی، ناهستی   
nâhastumandi, nâhasti

Fr.: non existence   

Math.: The fact that no → solution exists for a given → problem. In mathematics, nonexistence usually is a matter of impossibility.

non-; → existence.


Fr.: non flou   

Not → fuzzy. → nonfuzzy set.

non-; → fuzzy.

nonfuzzy set
  هنگرد ِ ناپرزوار   
hangard-e nâporzvâr

Fr.: ensemble non flou   

A set that obeys the rules of → classical logic, a → crisp set, as contrasted with a → fuzzy set.

nonfuzzy; → set.

nonholonomic system
  راژمان ِ ناهروداتیک   
râžemân-e nâharudâtik

Fr.: système non holonomique   

A mechanical system with constraints on their velocity that are not derivable from position constraints. Nonholonomic systems arise, for instance, in mechanical systems that have rolling contact (for example, the rolling of wheels without slipping) or certain kinds of sliding contact (such as the sliding of skates). They are a remarkable generalization of classical Lagrangian and Hamiltonian systems in which one allows position constraints only.

non-; → holonomic; → system.

nâhamgen (#)

Fr.: non homogène   

Not homogeneous. → nonhomogeneous linear differential equation.

non-; → homogeneous.

nonhomogeneous linear differential equation
  هموگش ِ دگرسانه‌ای ِ خطی ناهمگن   
hamugeš-e degarsâne-yi-ye xatti nâhamgen

Fr.: équation différentielle linéaire non homogène   

A → linear differential equation if Q(x)≠ 0 on interval I.

nonhomogeneous; → linear; → differential; → equation.

nâyonidé (#)

Fr.: non-ionisé   

The quality of an atom that has neither lost nor gained any electrons.

non-; → ionized.

nâxatti (#)

Fr.: non-linéaire   

Not a linear function of the relevant variables.
Containing a variable with an exponent other than one; opposite of → linear.

non-; → linear.

nonlinear device
  دستگاه ِ ناخطی   
dastgâh-e nâxatti

Fr.: dispositif non-linéaire   

An electronic device whose output is not directly proportional to its input. For example, in a → diode the current is a nonlinear function of the voltage; its voltage-current characteristics do not obey → Ohm's law.

nonlinear; → device.

nonlinear dynamics
  توانیک ِ ناخطی   
tavânik-e nâxatti

Fr.: dynamique non-linéaire   

Same as → chaos.

nonlinear; → dynamics.

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