An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -ph Pal par par par par pas Pav pen per per per per Per pet pha pho pho pho phy pie pla Pla pla pla pla plu poi pol pol pol pop pos pos pow Pra pre pre pre pri pri pro pro pro pro pro pro Pro pub pul Pyx > >>

Number of Results: 1001
parallel axis theorem
  فربین ِ آسه‌ها‌ی ِ پراسو   
farbin-e âsehâ-ye parâsu

Fr.: théorème des axes parallèles   

The → moment of inertia of a body about any given axis is the moment of inertia about a parallel axis through the center of mass, plus the moment of inertia about the given axis if the mass were located at the center of mass. same as → Steiner's theorem.

parallel; → axis; → theorem.

parallel of altitude
  پرهون ِ فرازا   
parhun-e farâzâ

Fr.: almucantar   

A small circle on the celestial sphere whose plane is parallel to the celestial horizon. Same as → almucantar.

parallel; → altitude.


  پراسورویه، لوزی‌وار   
parâsuruyé, lowzivâr

Fr.: parallélépipède   

A solid figure whose six bases are → parallelograms, opposite pairs being identical and parallel.

From Gk. parallelepipedon, from parallelos, → parallel + epipedon "plane surface," from neuter of epipedos "flat," from → epi- + pedon "ground," cognate with L. ped-, pes, → foot.

Parâsuruyé, from parâsu, → parallel, + ruyé, → surface. Lowzivâr, from lowzi, → rhombus + -vâr, → -oid.


Fr.: parallélogramme   

A four-sided → polygon whose opposite sides are parallel. A parallelogram all of whose angles are right angles is a → rectangle.

From Fr. parallélogramme, from L. parallelogrammum, from Gk. parallelogrammon "bounded by parallel lines," from parallelos, → parallel, + gramme "line," related to graphein "to write, draw" → -graph.

Parâsubar, from parâsu, → parallel, + bar, → side.


Fr.: para-aimant   

A paramagnetic substance, which possesses → paramagnetism.

para- + → magnet.


Fr.: paramagnétique   

Relative to or characterized by → paramagnetism.

para- + → magnetic


Fr.: paramagnétisme   

The property of a substance that possesses a → magnetic permeability greater than that of a vacuum but significantly less than that exhibited by → ferromagnetism. In the absence of an external magnetic field the atomic → magnetic moments of the substance are randomly oriented and thus cancel each other out with no net total magnetic moment. Moreover the coupling between neighboring moments is weak. However, when a magnetic field is applied magnetic moments align with the direction of the field and so the magnetic moments add together. Therefore paramagnetic substances affect external fields in a positive way, by attraction to the field resulting in a local increase in the magnetic field. The → magnetization vanishes when the field is removed.

para- + → magnetism


Fr.: paramètre   

General: Any of a set of physical properties whose values determine the characteristics or behavior of something. → impact parameter; → ionization parameter.
Math.: A constant or variable term in a function that determines the specific form of the function but not its general nature, as a in f(x) = kx, where k determines only the slope of the line described by f(x).

Mod.L. parametrum, from Gk. → para- + metron "measure," → meter.

Parâmun, from parâ-, → para-, + mun/mân "measure," as in Pers. terms pirâmun "perimeter," âzmun "test, trial," peymân "measuring, agreement," peymâné "a measure; a cup, bowl," from O.Pers./Av. mā(y)- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure."

parametric equation
  هموگش ِ پارامونی   
hamugeš-e pârâmuni

Fr.: équation paramétrique   

Any of a set of equations that defines the coordinates of the dependent variables of a curve or surface in terms of one or more independent variables or parameters.

parametric; → equation.

Paranal Observatory
  نپاهشگاه ِ پارانال   
nepâhešgâh-e Paranal

Fr.: Observatoire de Paranal   

An → ESO observatory, located on Cerro Paranal in the Atacama Desert, northern Chile, at 2,635 m altitude. It is about 120 km south of the town of Antofagasta and 12 km inland from the Pacific Coast. The Paranal Observatory hosts the → Very Large Telescope (VLT) with four 8.2 m telescopes. Each telescope provides one → Cassegrain and two → Nasmyth focus stations for facility instruments. One Nasmyth focus is available for visitor instruments. In addition each telescope is equipped with a → coudé focus station from which the light can be coherently combined in the interferometric focus. ESO also operates four 1.8 m Auxiliary Telescopes (ATs), that are used as an interferometric array (VISA) and a 4 m infrared survey telescope (VISTA). Currently, more than 10 instruments including two interferometric instruments (MIDI, AMBER) are operational and offered for science observations.

Paranal, the name of the mountain, in the Quechua language meaning "whirlwind;" → observatory.


Fr.: parapegme   

An astronomical and meteorological calendar written by ancient Greeks from 450 B.C. during at least three centuries. The parapegma was an inscribed stone for public use. It had holes beside the inscription, in which a peg could be inserted next to the appropriate day. The term was later applied to purely written forms of such calendars, or almanacs; plural form parapegmata.

From → para- "next to" + pegma "something that fastens something else together," from pegnyein "to stick."


Fr.: paraxial   

Characteristic of optical analyses that are limited to infinitesimally small apertures. Also called first-order or Gaussian optics.

para-; → axial.

From par(â)-, → para-, + âseyiaxial.

paraxial ray
  پرتو ِ پر‌آسه‌ای   
partow-e parâse-yi

Fr.: rayon paraxial   

A ray that lies close to and almost parallel to the optical axis and behaves according to paraxial equations.

paraxial, → ray.


Fr.: parent   

1) General: A father or a mother. A precursor, or → progenitor.
2) Physics: A → nuclide that upon → radioactive decay or → disintegration yields a specific nuclide (the → daughter). See also → parent cloud, → parent element, → parent galaxy, → parent molecule.

From O.Fr. parent, from L. parentem (nominative parens) "father or mother, ancestor," from parere "to bring forth, give birth to, produce," from PIE base *per- "to bring forth"

Permâr, literally "father-mother" (as in Sogd. māt-pitri "parent"), from Gilaki per, → father, + Gilaki mâr, → mother.

parent cloud
  ابر ِ پرمار   
abr-e permâr

Fr.: nuage parent   

Usually of a newborn star, the molecular cloud in which the star has formed.

parent; → cloud.

parent element
  بن‌پار ِ پرمار   
bonpâr-e permâr

Fr.: élément parent   

A radioactive element that spontaneously decays into a new substance. The product of this decay is known as a "daughter" element.

parent; → element.

parent galaxy
  کهکشان ِ پرمار   
kahkešân-e permâr

Fr.: galaxie parente   

Of a high redshift supernova, the galaxy in which the event has occurred.

parent; → galaxy.

parent molecule
  مولکول ِ پرمار   
molekul-e permâr

Fr.: molécule parente   

The molecule initially produced when a comet nucleus sublimates, soon changed to different daughter molecules because of solar radiation.

parent; → molecule.


Fr.: parhélie   

An optical phenomenon, seen as a halo in the form of a colored spot at the same angular elevation as the Sun. The most common parhelia are seen about 22° on either side of the Sun. Parhelia are caused by refraction of sunlight by ice crystals. Also called mock Sun or sundog.

From Gk. parhelion "a mock Sun," from → para- "beside" + helios "sun," → helio-.

Pârâhur, → para- + hur "sun," → helio-.

hamâli (#)

Fr.: parité   

1) General: Equality, as in amount, status, or character; equivalence; correspondence; similarity; analogy. Opposite of disparity.
2) Physics: The principle of space-inversion invariance.
An operation that reverses the algebraic sign of the coordinate axes used to describe a system, i.e. (x, y, z) → (-x, -y, -z). The parity principle is important in quantum mechanics because the wave functions which represent particles can behave in different ways upon transformation of the coordinate system. The parity is 1 (or even) if the wave function of the system is unchanged by an inversion of the coordinate system; it is -1 (or odd) if the wave function is changed only in sign. Parity is conserved in strong interactions, but not in weak ones.
3) Math.: The attribute, of an integer, of being even or odd. Thus, it can be said that 8 and 12 have the same parity, whereas 5 and 16 have opposite parity.
See also: → charge-parity symmetry, → even parity, → parity conservation, → parity symmetry, → parity violation.

From M.Fr. parité, from L.L. paritas "equality," from L. adj. par "equal."

Hamâli, quality noun of hamâl, → pair (equivalent 2).

<< < -ph Pal par par par par pas Pav pen per per per per Per pet pha pho pho pho phy pie pla Pla pla pla pla plu poi pol pol pol pop pos pos pow Pra pre pre pre pri pri pro pro pro pro pro pro Pro pub pul Pyx > >>