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

An astronomical object with usually weak emission in the → visible found to be the optical representation of the object radiating chiefly in other → wavelengths of the → electromagnetic spectrum.

→ optical; → counterpart.

1) A portion or division of a whole that is separate or distinct; piece, fragment, fraction, or section; constituent.
2) A section or division of a literary work (Dictionary.com).

M.E., from O.Fr. part "share, portion; character; dominion; side, path," from L. partem (nominative pars) "a part, piece, a share, a division; a party or faction," related to portio "share, portion," from PIE root *per- "to assign, allot;" cf. Pers. pâr, pâré "piece, part, portion, fragment;" as below.

Pâr, variant pâré "piece, part, portion," parré "portion, segment (of an orange)," pargâlé, "piece, portion; patch;" (dialects Kermâni pariké "portion, half;" Tabari perik "minute quantity, particle;" Lârestâni pakva "patch;" Borujerdi parru "patch"); Mid.Pers. pârag "piece, part, portion; gift, offering, bribe;" Av. pāra- "debt," from par- "to remunerate, equalize; to condemn;" PIE *per- "to sell, hand over, distribute; to assign;" Gk. peprotai "it has been granted;" L. pars, as above; Skt. purti- "reward;" Hitt. pars-, parsiya- "to break, crumble."

Being such in part only; not total or general; incomplete.
See also: → partial derivative, → partial differential equation, → partial eclipse, → partial ionization zone, → partial lunar eclipse, → partial solar eclipse, → partial truth.

M.E. parcial, from O.Fr. parcial, from M.L. partialis "pertaining to a part," from L. pars, → part; → -al.

→ part; → -al.

The derivative of a function of two or more variables, e.g., z = f(x,y), with respect to one of the variables, the others being considered constants (denoted ∂z / ∂x).

→ partial; → derivative.

A type of differential equation involving an unknown function (or functions) of several independent variables and its (or their) partial derivatives with respect to those variables.

→ partial; → differential; → equation.

An eclipse that is not total. → partial lunar eclipse, → partial solar eclipse.

→ partial; → eclipse.

One of several zones of the stellar interior where increased → opacity can provide the → kappa mechanism to drive → pulsations. See also → Kramers' law. In these zones where the gases are partially ionized, part of the energy released during a layer's compression can be used for further ionization, rather than raising the temperature of the gas. Partial ionization zones modulate the flow of energy through the layers of the star and are the direct cause of → stellar pulsation. The partial ionization zones were first identified by the Russian astronomer Sergei A. Zhevakin (1916-2001) in the 1950s. In most stars there are two main ionization zones. The hydrogen partial ionization zone where both the ionization of neutral hydrogen (H ↔ H⁺ + e^-) and the first ionization of helium (He ↔ He⁺ + e^-) occurs in layers with a characteristic temperature of 1.5 x 10⁴ K. The second, deeper zone is called the He⁺ partial ionization zone, and involves the second ionization of helium (He⁺↔ He⁺⁺ + e^-), which occurs deeper at a characteristic temperature of 4 x 10⁴ K. The location of these ionization zones within the star determines its pulsational properties. In fact if the → effective temperature of the star is ≥ 7500 K, the pulsation is not active, because the ionization zones will be located very near to the surface. In this region the density is quite low and there is not enough mass available to drive the oscillations. This explains the blue (hot) edge of the instability strip on the → H-R diagram. Otherwise if a star's surface temperature is too low, ≤ 5500 K, the onset of efficient convection in its outer layers may dampen the oscillations. The red (cool) edge of the instability strip is believed to be the result of the damping effect of convection. He⁺ ionization is the driving agent in → Cepheids. See also → gamma mechanism.

→ partial; → ionization; → zone.

A → lunar eclipse when the Earth's → umbra passes over only part of the Moon, causing only moderate darkening of the full Moon. See also → penumbral lunar eclipse.

→ partial; → lunar; → eclipse.

A → solar eclipse when only the → penumbra of the Moon touches the Earth. The → umbra passes either just above the North Pole or just below the South Pole, missing the Earth.

→ partial; → solar; → eclipse.

A → truth value in → fuzzy logic where it can range between "completely true" and "completely false."

→ partial; → truth.

To take part, be or become actively involved.

From L. paticipatus p.p. of partcipare "to share," from particeps "partaking, sharing," from part-, pars "part," → partial, + capere "to take," → concept.

Pârgertidan, from pâr "part," → partial, + gertidan "to take," → concept.

An act or instance of participating. The fact of taking part.

Verbal noun of → participate.

A lexical form derived from a verb, that has some of the characteristics and functions of both verbs and adjectives. In most Indo-European languages participles are used to express participation in an action (present participle) or relate to a completed action (past participle). They can also appear in attributive form as adjectives.

M.E., from O.Fr. participle, variant of participe, from L. participium, literally "a sharing, partaking," from particeps "sharing, partaking," → participate.

Pârgerté, from pârgert present stem of pârgertidan, → participate, + nuance suffix -é.

1) A unit of → matter smaller than the → atom or its main components. The term particle also includes any (currently hypothetical) new particles that might be discovered, such as the supersymmetric partners of the → quarks and → leptons and → bosons.
2) Mechanics: A material body (a body possessing mass) the size of which can be neglected in investigating its motion.
3) Grammar: In some languages, a word that has a grammatical function but does not fit into the main parts of speech (i.e. → noun, → verb, → adverb, → preposition). For example, in English, off, on, out, and up in call off, pass on, rule out, and grow up, respectively.
See also:
→ alpha particle, → antiparticle, → astroparticle physics, → beta particle, → charged particle, → elementary particle, → energetic solar particle, → exchange particle, → Lagrangian particle, → nanoparticle, → particle horizon, → particle nature, → particle physics, → relativistic particle, → resonance particle, → sink particle, → Smoothed Particle Hydrodynamics, → strange particle, → subatomic particle, → test particle, → virtual particle, → wave-particle duality.

From L. particula "little bit or part," diminutive of pars (genitive partis), from PIE base *per- "to assign, allot;" cf. Mid.Pers. pârag "gift, offering, bribe;" Mod.Pers. pâreh "gift" (→ partial); Gk. porein "to provide, give, grant," peprotai "it has been granted;" Skt. purtá- "gift, pay, reward."

Zarré, from Ar. dharrat "particle." Pârul, from pâr, → part, + -ul, → -ule.

For an observer at a given epoch t₀, the boundary between the observable and the unobservable regions of the → Universe. Therefore, the distance to the particle horizon at t₀ defines the size of the → observable Universe. Same as → cosmic horizon.

→ particle; → horizon.

A general term to describe → light involving the following phenomena: → reflection, → refraction, and → photoelectric effect. Compare → wave nature.

→ particle; → nature.

The branch of physics that deals with the smallest known structures of matter and energy in order to understand the fundamental particles and forces of nature.

→ particle; → physics.

1) (adj.) Of or pertaining to a single or specific person, thing, group, class, occasion, etc., rather than to others or all; special rather than → general.
2a) (n.) An individual or distinct part, as an item of a list or enumeration.
2b) (n.) Logic: An individual or a specific group within a general class (Dictionary.com).

M.E., from O.Fr. particuler and directly from L.L. particularis "of a part, concerning a small part," from L. particula, → particle, + -ar, → -al.

Pâruli, adj. from pârul, → particle; pârulé, from pârul + nuance adj. -é.

An → astrolabe that serves only a limited number of → latitudes.

→ particular; → astrolabe.

Of partial differential equations, the solution which can be obtained from the general solution by particular choice of the arbitrary functions. → general solution; → singular solution.

→ particular; → solution.