An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1965 Search : ion
co-rotational limit (CoRol)
  حد ِ هم-چرخشی   
hadd-e ham-carxeši

Fr.: limite co-rotationnelle   

For any rotating planetary body, a thermal limit beyond which the → rotational velocity at the equator intersects the → Keplerian orbital velocity. Beyond this corotation limit, a hot planetary body forms a structure, called a → synestia, with a corotating inner region connected to a disk-like outer region. Beyond this limit a body cannot have a single → angular velocity. It can instead exhibit a range of morphologies with disk-like outer regions. The (CoRoL is a function that depends upon the composition, thermal state, → angular momentum and mass of a body (Simon J. Lock nd Sarah T. Stewart, 2017, arXiv:1705.07858v1).

co-; → rotational; → limit.

  ماسش، رچش، لخته بندی   
mâseš, roceš, laxté bandi

Fr.: coagulation   

Verbal noun from → coagulate.
Physical chemistry: A separation or precipitation of particles from a dispersed state in a colloid solution.
Astrophysics: The mechanism by which dust grains grow into larger entities in the interstellar medium and protoplanetary disks. → dust coagulation.

Verbal noun from → coagulate.


Fr.: codéclinaison   

The complement of → declination; the angular distance along a great circle from the celestial pole, i.e., 90° - declination.

Codeclination, from → co- + → declination.

Hamvâkil, from ham-, → co-, + vâkil, → declination.


Fr.: coercition   

The act, practice, or power of using physical or moral force to compel a person to do something.

Verbal noun of → coerce.

šenâxtâr (#)

Fr.: connaissance, cognition   

1) The mental process of knowing, including → awareness, → perception, → reasoning, and judgment.
2) The product of such a process; something thus known, perceived, etc. (

M.E. cognicioun; L. cognitionem (nominative cognitio, from cognitus p.p. of cognoscere, from → co- + gnoscere, noscere "to learn;" cognate with Pers. šenâs, šenâxt, as below.

Šenâxtâr, verbal noun of šenâxtan "to know, recognize," dânestan "to know;" O.Pers./Av. xšnā- "to know, learn, come to know, recognize;" cf. Skt. jñā- "to recognize, know," jānāti "he knows;" Gk. gignoskein "to know, think, judge;" L. gnoscere, noscere "to come to know" (Fr. connaître; Sp. conocer); O.E. cnawan; E. know; Rus. znat "to know;" PIE base *gno- "to know."

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.

cold accretion flow
  تچان ِ فربال ِ سرد   
tacân-e farbâl-e sard

Fr.: écoulement d'accrétion froid   

1) A type of → accretion flow by a → compact object such as a → black hole that consists of cool → optically thick gas and has a relatively high mass → accretion rate, in contrast to → hot accretion flows.
2) Gas accreting from the → intergalactic medium (IGM) onto → galactic haloes with sufficiently low velocities so that it will not be shocked to the → virial temperature of the halo, but will instead flow at a relatively low temperature (T ~ 104 K). Galaxies grow by accreting gas from → cosmic filaments. Feedback from star formation and → active galactic nuclei returns a significant fraction of the → interstellar medium (ISM) to the halo and may even blow it out of the halo into the IGM. This "cold accretion" will happen if the cooling time of → virialized gas is too short to maintain a hot, → hydrostatic halo. The existence of such a cold accretion mode has been confirmed by simulations, which have furthermore demonstrated that cold mode accretion can also be important for halos sufficiently massive to contain hot, hydrostatic gas. Because gas accretes preferentially along the filaments of the cosmic web, the streams of infalling gas have relatively high gas densities and correspondingly low cooling times. This allows the cold streams to penetrate the hot, hydrostatic halos surrounding massive galaxies, particularly at → high redshifts (F. van de Voort et al., 2012, MNRAS 421, 2809).

cold; → accretion; → flow.

cold disk accretion
  گرده‌ی ِ فربال ِ سرد   
gerde-ye farbâl-e sard

Fr.: disque d'accrétion froid   

An accretion process whereby material coming from an → accretion disk settles onto the → protostellar surface through a geometrically thin layer or thin accretion columns. Heat brought into the protostar in the accretion flow radiates freely into space until the temperature attains the photospheric value. Most of the stellar surface is unaffected by the accretion flow (see, e.g., Hosokawa et al. 2010, ApJ 721, 478).

cold; → disk; → accretion.

hamkâri (#)

Fr.: collaboration   

The act or process of working with another or others on a joint project.

From Fr. collaboration, noun of action from L. collaborare from → com- "with" + labore "to work."

Hamkâri, from ham-, → com-, + kâr, → work, + -i verbal noun suffix.

collapse of the wave function
  رمبش ِ کریای ِ موج   
rombeš-e karyâ-ye mowj

Fr.: effondrement de la fonction d'onde   

The idea, central to the → Copenhagen Interpretation of quantum theory, whereby at the moment of observation the → wave function changes irreversibly from a description of all of the possibilities that could be observed to a description of only the event that is observed. More specifically, quantum entities such as electrons exist as waves until they are observed, then "collapse" into point-like particles. According to the Copenhagen Interpretation, observation causes the wave function to collapse. However it is not known what causes the wave function to collapse. Same as → wave collapse.

collapse; → wave function.

  گرد‌آورش، گرد‌آورد، گرد‌آمد، گرد‌آیند   
gerdâvareš, gerdâvard, gerdâmad, gerdâyand (#)

Fr.: collection   

1) The act or process of collecting.
2) A group of objects or works to be seen, studied, or kept together.

Verbal noun from → collect.

collective star formation
  دیسش ِ گرد‌آمدی ِ ستارگان   
diseš-e gerdâmdi-ye setâregân

Fr.: formation collective d'étolies   

Formation of stars, especially → massive stars, in group as opposed to individual formation.

collective; → star; → formation.

  گرد‌آمدش، گرد‌آمدکرد   
gerâmadideš, gerâdmad-kard

Fr.: collectivisation   

The process of forming collectives or collective communities where property and resources are owned by the community and not individuals (

Verbal noun of → collectivize.


Fr.: collimation   

1) The process of restricting a beam of photons or particles to a given area.
2) The process of adjusting a telescope to place all optical elements in precise alignment. → align a telescope.

Verbal noun of → collimate.


Fr.: collision   

The act or process of colliding, → collide.

Verbal noun from → collide .


Fr.: collisionnel   

Of or relating to → collision.

collision; → -al.

collisional cross section
  سکنج ِ اسکرمند ِ همکوبشی   
sekanj-e oskarmand-e hamkubeši

Fr.: section efficace de collision   

Same as → cross section.

collisional; → cross; → section.

collisional decay
  تباهی ِ همکوبشی   
tabâhi-ye hamkuneši

Fr.: désexcitation collisionnelle   

The process when the energy difference between the excited and non excited states of an atom is taken away by an electron during a collision.

collisional; → decay.

collisional excitation
  بر‌انگیزش ِ همکوبشی   
barangizeš-e hamkubeši

Fr.: excitation collisionnelle   

A physical process which is caused by the free electrons that are energized either by → photoionization or → collisional ionization. Collisional excitation puts ions, atoms, and molecules into excited states from which they may decay radiatively. Collisional excitation is important in the → interstellar medium.

collisional; → excitation.

collisional heating
  گرمش ِ همکوبشی   
garmeš-e hamkubeši

Fr.: chauffage par collisions   

A physical process whereby heat is imparted to (e.g. → interstellar dust grains or → molecular hydrogen) through collisions (with hot electrons, ions, etc.).

collisional; → heating.

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