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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1234
community
  ۱) همدارگان؛ ۲) همداری   
1) hamdârgân; 2) hamdâri

Fr.: communauté   

1a) A social group whose members share common characteristics or interests, such as values, identity, and often a common location (e.g. a village, town, or neighborhood).
1b) Ecology: A group of populations of different species (plants and animals) within a specified location in space and time. 2) Common ownership or participation; joint possession.

Ultimately from L. communitas "partnership, society, fellowship," from communis, → common "common, public, general," + -itas, → -ity

Hamdârgân, from hamdâr, → common, + -gân suffix forming plural entities, from Mid.Pers. -gânag, -gâna, on the model of hamegân, → public.

commutation
  هم‌موتش   
hammuteš

Fr.: commutation   

General: A substitution, exchange, or interchange.
Electronics: The transfer of current from one channel to another in a gas tube.
Electricity: The reversal of direct current into alternating current.
Math: A commutative operation, where a . b = b . a.

Noun from → commute.

commutation rules
  رزن‌های ِ هم‌موتش   
razanhâ-ye hammuteš

Fr.: règles de commutation   

The specification of commutators of operators that in quantum physics correspond to the coordinates and momenta of a system.

commutation; → rule.

commutative
  هم‌موتنده   
hammutandé

Fr.: commutatif   

(adj.) Of or pertaining to → commutation.

Adj. from → commute.

commutative law
  قانون ِ هم‌موتشی   
qânun-e hammuteši

Fr.: loi commutative   

A principle holding for the operations of addition and multiplication (in some number domains) that asserts that the consequence of the given operation is not affected by the order in which the terms are considered. Thus x + y = y + x; x . y = y . x.

commutative; → law. The first use of the word commutative in this sense is ascribed to the French mathematician François Joseph Servois (1768-1847).

commutativity
  هم‌موتندگی   
hammutandegi

Fr.: commutativité   

The state or quality of being commutative.

Noun from → commutative.

commutator
  هم‌موتگر   
hammutgar

Fr.: commutateur   

Math.: The commutator of a and b is the element c of a group such that bac = ab.

Agent noun from → commute.

commute
  هم‌موتیدن   
hammutidan

Fr.: échanger   

To substitute (one thing for another); exchange. → mutation.
Math., logic: To satisfy or engage in a commutative operation.

From L. commutare "to change altogether," from → com- + mutare "to change," from PIE base *mei- "to change, go, move;" cf. Av. miθô "inverted, false," miθaoxta- "wrong spoken;" Skt. methati "changes, alternates, joins, meets," mithah "mutual, reciprocal;" L. meare "to go, pass," mutuus "done in exchange;" Goth. maidjan "to change;" E. prefix mis- (in mistake).

Hammutidan, from ham-com- + mut, from L. mutare cognate with Av. miθô, as above, + -idan infinitive suffix.

comoving
  هم‌جنب، هم‌میاو   
hamjonb, ham-miyâv

Fr.: comobile   

Moving together or in a correlated way.

From → com- "together," + pr.p. of → move.

Hamjonb, ham-miyâv "comoving," from ham- "together," → com-, + jonb or miyav "moving, mover," present stems of jondidan and miyâvidan "→ move."

comoving coordinates
  هماراهای ِ هم‌جنب   
hamârâhâ-ye hamjonb

Fr.: coordonnées comobiles   

A system of coordinates used in cosmology which is fixed with respect to the overall → Hubble flow of the universe. A given galaxy's location in comoving coordinates does not change as the Universe expands.

comoving; → frame.

comoving distance
  دورای ِ هم‌جنب   
durâ-ye hamjonb

Fr.: distance comobile   

1) A distance in → comoving coordinates between two points in space at a given cosmological time. In other words, the distance between two nearby objects in the Universe which remains constant with epoch if the two objects are moving with the → Hubble flow. Comoving time is deduced from the → Robertson Walker metric. The comoving distance corresponds to the current size of the → cosmic horizon, i.e. about 48 × 109light-years. See also → look-back time.
2) Line-of-sight comoving distance: The total line-of-sight comoving distance from us to a distant object is computed by integrating the infinitesimal comoving distance contributions between nearby events along the radial ray from redshift 0 to the object.
3) Transverse comoving distance: The comoving distance between two events at the same → redshift but separated on the sky by some angle.

comoving; → distance.

comoving frame
  چارچوب ِ هم‌جنب   
cârcub-e hamjonb

Fr.: rérérentiel comobile   

A → reference frame that is attached to a moving object. The object in this frame is therefore at rest.

comoving; → frame.

comoving volume
  گنج ِ هم‌جنب   
gonj-e hamjonb

Fr.: volume comobile   

The volume that a structure at → redshift  z would have if it was seen at the current cosmological epoch (defined by z = 0).

comoving; → volume.

compact
  ۱) همپک؛ ۲) همپکیدن، همپک کردن   
1) hampak; 2) hampakidan, hampak kardan

Fr.: 1) compacte; 2) condenser, resserer   

1) Closely and firmly joined or packed together; Occupying little space compared with others of its type.
2) To reduce in size or volume.

M.E., from L. compactus "concentrated," p.p. of compingere "to fasten together," from → com- "with, together" + pangere "to fix, fasten," cf. Gk. pegnunai "to fasten, coagulate;" PIE *pag-/*pak- "to fasten."

1) Hampak, from ham-, → com-, + pak, from pakidé [Mo'in, Dehxodâ] "thick, dense, compact," in Hamadâni pukida "much, full, abundant," Kordi pêk "together, joint," pêk hatin "to be made up of," pêk hênan "to collect, constitute," from PIE *pag-/*pak- as above?
2) Hampakidan, from hampak + -idan infinitive suffix; hampak kardan, from hampak + kardan "to do, make, perform," → -ize.

compact binary star system
  راژمان ِ درین ِ همپک   
râžmân-e dorin-e hampak

Fr.: système binaire compact   

A binary star system which is composed of a collapsed object (→ degenerate dwarf, → neutron star, or → black hole) in orbit with a low-mass (≤ 0.5 Msol) secondary star, wherein the collapsed star → accretes matter from its → companion. These two objects form a binary system of overall dimensions 106 km with an orbital period of only hours or less. See also: → X-ray binary.

compact; → binary; → star; → system.

compact central object (CCO)
  بر‌آخت ِ همپک ِ مرکزی   
barâxt-e hampak-e markazi

Fr.: objet compact central   

An → X-ray source detected close to the center of young → supernova remnant (SNR)s that has no apparent emission in other wave-bands and no binary companions. Although these sources have been known and studied for several decades without much understanding of their nature, exciting results over the past few years have brought them into the forefront of → neutron star studies. They have soft, exclusively thermal spectra in the few hundred eV range and X-ray luminosities around 1033 - 1034 erg s-1. About ten CCOs are presently known, including the central sources of CasA, Puppis A and Kes 79 supernova remnants. Several, J1852+0040 in Kes79, J0822.0-4300 in Puppis A and 1E 1207.4-5209 in PKS 1209-51/52, have detected pulsations in the hundreds of milliseconds range. J1852+0040 has a detected → period derivative, indicating that it is spinning down like a → rotation-powered pulsar (RPP). The measured period and either measurements or constraints on period derivative indicate that these sources have very low → magnetic fields in the range 1010 - 1011 G assuming magnetic dipole braking. Since their SNRs are all young, ~ 103 - 104 yr, they were probably born with unusually low magnetic fields, which makes them "anti-magnetars" (A. K. Harding, 2013, Front. Phys. 8, 679 and references therein).

compact; → central; → object.

compact galaxy
  کهکشان ِ همپک   
kahkašân-e hampak

Fr.: galaxie compacte   

A galaxy with no disk or nebulous background and a high surface brightness that appears only barely larger than a star-like point on a sky survey photograph.

compact; → galaxy.

compact H II region
  ناحیه‌ی ِ H IIی ِ همپک   
nâhiye-ye H II-ye hampak

Fr.: région H II compacte   

A Galactic H II region with an electron density ≥ 103 cm-3 and of a linear dimension ≤ 1 pc.

compact; → H II region.

compact high-velocity clouds (CHVCs)
  ابرهای ِ همپک ِ تندرو   
abrhâ-ye hampak-e tondrow

Fr.: nuages compacts à grande vitesse   

A population of relatively small (typically < 2°) → high-velocity clouds, which are spatially and kinematically isolated from the gas distribution in their environment. They are thought to be located in the → intergalactic medium of the → Local Group.

compact; → high-velocity cloud.

compact massive galaxy (CMG)
  کهکشان ِ پرجرم ِ همپک   
kahkešân-e porjerm-e hampak

Fr.: galaxie massive compacte   

A galaxy with a stellar mass of M ≥ 1011Msun and an → effective radius of Re ≤ 1.5 kpc. Many studies have shown that massive galaxies with low → star formation rates were remarkably compact at a → redshift of z≥ 2. At fixed stellar mass of Mstars ≅ 1011Msun, quiescent galaxies are a factor of ~ 4 smaller at z = 2 than at z = 0. As the stellar mass of the galaxies also evolves, the inferred size growth of individual galaxies is even larger. It is unlikely that all massive galaxies in the present-day Universe had a compact progenitor. However, the vast majority of CMGs that are observed at z = 2 ended up in the center of a much larger galaxy today. Their size growth after z = 2 is probably dominated by minor → mergers. Such mergers are expected because other mechanisms cannot easily produce the observed scaling between size growth and mass growth (P. G. van Dokkum1 et al., 2015, ApJ 813, 23).

compact; → massive; → galaxy.

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