An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1234
coherence
  همدوسی   
hamdusi (#)

Fr.: cohérence   

The property of two or more electromagnetic waves when they are in fixed phase relationship over time. If the crests and troughs of the waves meet at the same time and place they are said to be in phase.

cohere + -ence, → -ance.

coherence area
  پهنه‌ی ِ همدوسی   
pahne-ye hamdusi

Fr.: zone de cohérence   

Of an electromagnetic wave, the area of a surface perpendicular to the direction of propagation, over which the electromagnetic wave maintains a specified degree of coherence.

coherence; → area.

coherence length
  درازا‌ی ِ همدوسی   
derâzâ-ye hamdusi

Fr.: longueur de cohérence   

The distance over which an electromagnetic wave train maintains a specified degree of coherence.

coherence; → length.

coherence time
  زمان ِ همدوسی   
zamân hamdusi

Fr.: temps de cohérence   

The time over which a propagating electromagnetic wave may be considered coherent. The coherence time of an interferometer is the interval during which the fringe phase remains stable.

coherence; → time.

coherent
  همدوس   
hamdus (#)

Fr.: cohérent   

Two or more wave sources are said to be coherent sources if the phase difference between a pair of points, one in each source, remains constant.

Coherent, adj., → coherence.

coherent light
  نور ِ همدوس   
nur-e hamdus (#)

Fr.: lumière cohérente   

Light waves that have the same wavelength and possess a fixed phase relationship, as in a laser.

coherent; → light.

coherent optics
  نوریک ِ همدوس   
nurik-e hamdus

Fr.: optique cohérente   

A branch of optics that uses coherent radiation to produce holographic three-dimensional images of objects.

coherent; → optics.

coherent scattering
  پراکنش ِ همدوس   
parâkaneš-e hamdus

Fr.: diffusion cohérente   

A scattering process in which the scattered radiation bears the same frequency and phase as the incident radiation.

coherent; → scattering.

coherent source
  خن ِ همدوس   
xan-e hamdus

Fr.: source cohérente   

One of two light beams derived from the same source in → interference experiments. It is impossible to obtain interference from two separate sources because their → wavefronts do not have a constant → phase difference. In → Young's experiment, → Fresnel's biprism, → Fresnel's mirrors, and → Lloyd's mirror the two sources always have a point-to-point correspondence of phase, since they are both derived from the same source.

coherent; → source.

cohesion
  همدوسش   
hamduseš (#)

Fr.: cohésion   

Holding together.
Physics: The attraction between the molecules of a solid or liquid that holds the parts of the substance together.

From L. cohæsus, p.p. of cohærere "to stick together," → coherence.

Hamduseš, verbal noun from hamdusidan "to cohere," → coherence.

cohesive
  همدوسنده، همدوسشی   
hamdusandé, hamduseši

Fr.: cohésif   

1) Of or pertaining to the molecular force → cohesion.
2) Characterized by or causing → cohesion.

Adjective from → cohere.

cohesive energy
  کاروژ ِ همدوسش   
kâruž-e hamduseš

Fr.: énergie de cohésion   

The energy associated with the chemical bonding of atoms in a solid.

cohesive; → energy.

cohesive force
  نیروی ِ همدوسش   
niru-ye hamduseš

Fr.: force cohésive, ~ de cohésion   

The force of → attraction between the molecules of the same substance.

cohesive; → force.

coil
  پیچه   
picé (#)

Fr.: bobine   

A device consisting of a length of electrical wire wound in a spiral to provide magnetic field by → electromagnetic induction.

Maybe from M.E. cull, from M.Fr. culier, coillir "to gather," from L. colligere "to bind together," → collect.

Picé "a curled, a twisted figure or object," from picidan "to twist, invove, enttwine, coil."

coincide
  برهم‌افتادن، هم‌افتادن   
barhamoftâdan, hamoftâdan

Fr.: coïncider   

1) (Of two more objects) to correspond in area and outline; to occupy the same place.
2) To happen at the same time.

Coincide, from Fr. coincider, from M.L. coincidere, from L. → co- "together" + incidere "to fall upon," from in- "upon" + cadere "to fall," PIE base *kad- "to fall".

Barhamoftâdan, from bar- "to, upon, together" + oftâdan "to fall," Mid.Pers. patet "falls," opastan "to fall," Av. pat- " to fly, fall, rush," cf. Skt. patati "he flies, falls," L. petere "to fall, rush out," Gk. piptein "to fall," petomai "I fly," PIE base *pet- "to fly, to rush."

coincidence
  برهم‌افت، هم‌افت، هم‌افتاد   
barhamoft, hamoft, hamoftâd

Fr.: coïncidence   

1) Fact, event, or condition of coinciding.
2) The occurrence of events simultaneously in a striking manner but without any causal connexion between them.

coincide.

coincident
  برهم‌افتان، هم‌افتان   
barhamoftân

Fr.: coïncident   

Occupying the same area in space or happening at the same time. Of two geometric figures, matching point for point.

From Fr. coincident, from M.L. coincident-, coincidens, pr.p. of coincidere, → coincide.

coincide.

colatitude
  هم‌وَرونا   
ham-varunâ

Fr.: colatitude   

The polar angle on a sphere measured from the north pole instead of the equator; equal to "90° - latitude".

co- + → latitude.

cold
  سرد   
sard (#)

Fr.: froid   

Having a relatively low temperature.

M.E., from O.E. cald, ceald "cold, cool" (cf. O.Fr. and O.Sax. kald, O.H.G. and Ger. kalt, Goth. kalds "cold"), from PIE root *gel-/*gol- "cold;" cf. L. gelare "to freeze," gelu "frost," glacies "ice;" Kurd. girsân, girsiân "to coagulate" (Cheung 2007).

Sard "cold, cool," afsordan, afsârdan "to congeal;" Mid.Pers. sard/sart "cold;" Av. sarəta- "cold;" cf. Skt. śiśira- "cold;" L. calidus "warm;" Lith. šaltas "cold;" Welsh clyd "warm;" PIE *keltos- "cool."

cold absorber
  درشمگر ِ سرد   
daršamgar-e sard

Fr.: absorbeur froid   

A broad → absorption feature observed in → X-ray spectra of → active galactic nuclei (AGN). It is caused by material associated with the → interstellar medium in our → Galaxy and/or the host galaxy of the AGN or cold material near the AGN. → Quasars commonly have their X-ray spectrum absorbed by cold gas between us and the quasar X-ray source (along our → line of sight). This is particularly common in less luminous quasars. See also → warm absorber.

cold; → absorber.

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