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

In data processing, a quantity used to alter an instruction in a prescribed way to produce the instruction actually obeyed.

Agent noun of → modify.

To change somewhat the form or qualities of; alter partially; amend.
To reduce or lessen in degree or extent; moderate; soften:

From O.Fr. modifier, from L. modificare "to impose a rule or pattern, regulate, restrain," from modus "measure, rhythm, song, manner" PIE base *med-/*met- "to measure, limit, consider, advise, take appropriate measures" + root of facere "to make"

Vâtarzidan, from vâ- prefix denoting "reversal, opposition; separation; repetition; open; off; away" (variant of bâz-, from Mid.Pers. abâz-, apâc-; O.Pers. apa- [pref.] "away, from;" Av. apa- [pref.] "away, from," apaš [adv.] "toward the back;" cf. Skt. ápāñc "situated behind") + tarz "mode, manner" + -idan infinitive suffix.

General: To regulate by or adjust to a certain measure or proportion; tone down. Physics: To alter the value of some parameter characterizing a periodic oscillation. → modulation.

From L. modulatus pr.p. of modulari "to regulate, measure off properly," from modulus "small measure," diminutive of modus "measure, manner," → mode.

Degarâhangidan, from degar "other, another," denoting change, variant digar (Mid.Pers. dit, ditikar "the other, the second;" O.Pers. duvitiya- "second," Av. daibitya-, bitya- "second;" Skt. dvitiya- "second," PIE *duitiio- "second") + âhang "melody, pitch, tune, modulation" (ultimately from Proto-Iranian *āhang-, from prefix ā- + *hang-, from PIE base *seng^wh- "to sing, make an incantation;" cf. O.H.G. singan; Ger. singen; Goth. siggwan; Swed. sjunga; O.E. singan "to chant, sing, tell in song;" maybe cognate with Gk. omphe "voice; oracle") + -idan infinitive suffix.

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.

General: The modification of some property of a phenomenon by another distinct phenomenon.
Physics: Variation of some characteristic (amplitude, phase, or frequency) of a radio wave, called the carrier wave, in accordance with instantaneous values of another wave, called the modulating wave. → amplitude modulation; → frequency modulation.
Optics: A synonym for contrast, particularly when applied to a series of parallel lines and spaces imaged by a lens.

Verbal noun of → modulate.

A measure of the ability of an optical system to reproduce (transfer) various levels of detail from the object to the image, as shown by the degree of contrast (modulation) in the image. → optical transfer function.

→ modulation; → transfer; → function.

Any device for effecting the process of modulation.

from L. modulator, from → modulate + -tor a suffix forming personal agent nouns from verbs.

Vâhangâr, from vâhang, → modulation, + -âr, contraction of âvar agent noun of âvardan "to bring; to cause, produce" (Mid.Pers. âwurtan, âvaritan; Av. ābar- "to bring; to possess," from prefix ā- + Av./O.Pers. bar- "to bear, carry," bareθre "to bear (infinitive)," bareθri "a female that bears (children), a mother;" Mod.Pers. bordan "to carry;" Skt. bharati "he carries;" Gk. pherein; L. fero "to carry").

A distinct and separable element of a spacecraft or space station.

From M.Fr. module, from L. modulus "small measure," diminutive of modus "measure, manner," → mode.

Modul, loan as above. Tarzul, from tarz→ mode + -ul, → -ula.

An open-source, one-dimensional astrophysical code which is capable of calculating the evolution of stars in a wide range of environments. It works according to the → Henyey method and uses many modules that deal with various aspects of the theoretical models, such as the → equation of state (EOS), → nuclear reaction networks, → chemical composition, micro-physics, or macro-physics. The EOS and corresponding opacities or nuclear networks are provided in tabulated formats and can be selected by the user, while the micro-physics and macro-physics can be controlled by inlists of relevant parameters and settings (Paxton et al. 2015, ApJS 220, 15 and references therein).

→ module; → experiment; → stellar; → astrophysics.

A real, positive quantity that measures the magnitude of some number. For instance, the modulus of a complex number is the square root of the sum of the squares of its components. Often it means, simply, the numerical ("absolute") value of an algebraic quantity.

From L. modulus, → module.

Peymun, variant of peymâné "a measure either for dry or wet goods; a bushel, cup, bowl," from peymudan, peymâyidan "to measure," from Mid.Pers. patmudan, paymudan "to measure (against)," from *pati-māya-. The first element *pati- "against, back" (cf. Mod.Pers. pâd- "agaist, contrary to;" Mid.Pers. pât-; O.Pers. paity "agaist, back, opposite to, toward, face to face, in front of;" Av. paiti; Skt. práti "toward, against, again, back, in return, opposite;" Pali pati-; Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti). The second element from *mā- "to measure;" O.Pers./Av. mā(y)- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure." Apart from peymâné, several other terms in Mod.Pers. are related to this second element, which occurs also as mun, mân, man, mâ, mu, and mây: pirâmun "perimeter," âzmun, âzmây- "test, trial," peymân "measuring, agreement," man "a measure weighing forty seers"), nemudan, nemâ- "to show, display," âmâdan, âmây- "to prepare."

Same as → shear modulus.

→ modulus; → rigidity.

Describing a quantity of substance that is proportional to its molecular weight. Relating to a → mole.

→ mole + → -ar.

Of a gas included in the composition of a → gas mixture, the ratio of the number of moles of this gas to the total number of moles of all the gases in the mixture. Same as mole fraction and mole-fraction concentration.

→ molar; → concentration.

The → heat capacity of one → mole of substance: C_μ = μ C, where μ is the → molecular weight and C the → specific heat capacity. The molar heat capacity of water is practically 18 cal/mole.C°.

Molar, adj. of → mole; → heat; → capacity.

The amount of heat energy required to vaporize 1 mole of a liquid at its → boiling point, usually expressed in kJ/mol.

→ molar; → heat; → vaporization.

The → SI unit of amount of → substance; symbol mol. One mole contains exactly 6.022 140 76 × 10²³ elementary entities. This number is the fixed numerical value of the → Avogadro constant, N_A, when expressed in the unit mol^-1.

From Ger. Mole, short for Molekül, from Fr. → molecule.

Of or pertaining to or caused by molecules.

From → molecule + -ar variant of the adjective-forming suffix → -al, joined to words in which an l precedes the suffix.

Molekuli, from molekul→ molecule + -i adj. suffix.

A band of molecular origin present in a spectrum. See for example → cyanogen band, → S star.

→ molecular; → band.

A relatively dense, cold region of interstellar matter where the atoms are primarily bound together as molecules rather than free atoms or ionized particles. Molecular clouds represent the coldest and densest phase of the → interstellar medium. They consist primarily of → molecular hydrogen (H₂), with temperatures in the range 10-100 K. Molecular hydrogen is not directly observable under most conditions in molecular clouds. Therefore, almost all current knowledge about the properties of molecular clouds has been deduced from observations of molecules such as → carbon monoxide (CO), which have strong emission lines mainly in the → millimeter portion of the → electromagnetic spectrum. So far 129 molecular species have been detected in molecular clouds, among which complex organic molecules. → Dust grains in molecular clouds play a crucial role in the formation of molecules. Molecular clouds are the principal sites where stars form. → giant molecular cloud; → Orion molecular cloud.

→ molecular; → cloud.

One of many compact and dense sub-structures in a → molecular cloud. Their typical sizes are about 0.5-10 → parsecs and their masses range from about 50 to 10³ → solar masses. The gas temperatures are about 10-20 K, and the number densities from about 10³ to 10⁴ cm^-3.

→ molecular; → clump.