An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1234
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 dark matter (CDM)
  ماده‌ی ِ سرد ِ تاریک   
mâdde-ye sard-e târik (#)

Fr.: matière noire froide   

Any → hypothetical → non-baryonic  → dark matter that is → non-relativistic at the point of → decoupling in the → early Universe. CDM plays a key role in → cosmic structure formation. See also → CDM model, → lambda cold dark matter, → Meszaros effect, → missing satellites problem.

cold; → dark; → matter.

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.


Fr.: collapsar   

The collapse of the core of a very massive star which results in a black hole accompanied by a very energetic → gamma-ray burst.

From collaps(e) + (st)ar.

  ۱) رمبیدن؛ ۲) رمبش   
1) rombidan (#); 2) rombeš (#)

Fr.: 1) s'effondrer; 2) effondrement   

1) (v.) To fall inward abruptly under its own → gravity.
2) (n.) The act of falling inward abruptly under its own gravity. → gravitational collapse; → core collapse.

From L. collapsus, p.p. of collabi "fall together," from → com- "together" + labi "to fall, slip."

1) Mod.Pers. rombidan "to fall apart, to crumble," Hamadâni, Malâyeri: rommidan, Lori remese "get destroyed," remane "to destroy a building," possibly cognate with E. crumble "to break into small fragments," from O.E. cruma, akin to D. kruim, Ger. Krume "crumb," L. grumus "heap of earth," root of Fr. grumeau "lump."
2) Rombeš from present stem romb "collapse" + noun suffix -eš.

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.

collapsed star
  ستاره‌ی ِ رمبیده   
setâre-ye rombidé

Fr.: étoile effondrée   

A star that has undergone → collapse.

Collapsed p.p. of → collapse; → star.

Setâré, → star; rombidé p.p. of rombidan, → collapse.

  ۱) گرد‌آوردن، انباشتن؛ ۲) گرد‌آمدن   
1) gerdâvardan (#), anbâštan (#); 2) gerdâmadan

Fr.: 1) collecter, réunir, accumuler, ramasser; 2) s'accumuler, se réunir   

1a) To bring together into a one body or place.
1b) To gather and gradually accumulate in a place.
2) to gather together; assemble.

From O.Fr. collecter, from L. collectus, p.p. of colligere "gather together," from → com- "together" + legere "to gather," cf. L. lignum "wood, firewood," lit. "that which is gathered"; cognate with Gk. legein "to say, tell, declare," from PIE *leg- "to pick together, gather, collect"

1) Gerdâvardan "to collect," from gerd "round; around," → disk; alternatively, ultimately from PIE base *ger- "to gather," cf. Iranian ger-, gor-, etc. "to gather," → category, + âvardan "to bring," → production.
Anbâštan, anbârdan "to fill, to replete;" Mid.Pers. hambāridan "to fill;" from Proto-Iranian *ham-par-, from prefix ham-, → com-, + par- "to fill;" cf. Av. par- "to fill," parav-, pauru-, pouru- "full, much, many;" O.Pers. paru- "much, many;" Mid.Pers. purr "full;" Mod.Pers. por "full, much, very;" PIE base *pelu- "full," from *pel- "to be full;" cf. Skt. puru- "much, abundant;" Gk. polus "many," plethos "great number, multitude;" O.E. full.
2) Gerdâmadan "to come together," with âmadan "to come," → efficiency.

collect and collapse model
  مدل ِ انباشت و رمبش   
model-e anbâšt va rombeš

Fr.: modèle d'accumulation et d'effondrement   

A → sequential star formation model involving → massive stars and → H II regions. The energetic ultraviolet photons from a massive star born in a → molecular cloud drive a spherical → ionization front radially outward from the star at a velocity much higher than the → sound speed in the cold neutral gas. The supersonic expansion of the H II region through the surrounding neutral gas creates a → shock front, sweeping up an increasingly massive and dense shell of cool neutral gas. This is the collect phase of the process in which the H II region simply acts like a snowplough. If the expansion of the H II region continues for long enough, the surface density of the shell increases to the point where the shell becomes self-gravitating. The shell is then expected to collapse and fragment. Individual fragments may then enter a non-linear collapse phase, possibly forming massive stars. This model was first proposed by Elmegreen & Lada (1977, ApJ 214, 725), who used a one-dimensional analysis. Whitworth et al. (1994, MNRAS, 268, 291) developed an analytical model for the collect and collapse process which predicts the fragmentation time, the size, number, and mass of the fragments (see also Elmegreen 1998, in ASP Conf. Ser. 148, Origins, eds. Woodward et al., p. 150 and references therein). → stimulated star formation, → triggered star formation.

collect; → collapse; → model.

collecting area
  پهنه‌ی ِ گرد‌آور   
pahne-ye gerdâvar

Fr.: surface collectrice   

Of an interferometric telescope made up of several mirrors, the hypothetical mirror created by the combination of the individual mirrors.

collect; → area.

  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.


Fr.: collectif   

Forming a whole; of or characteristic of a group taken together.

collect + → -ive.

collective behavior
  رفتار ِ گرد‌آمدی   
raftâr-e gerdâmadi

Fr.: comportement collectif   

1) The whole behavior of a system of many interacting components, which differs from that of the individual components. Some classical examples are the → many-body problem, → phase transition, most of thermodynamic phenomena, collective oscillations occurring in solids, etc. Physics dealt with collective behavior much earlier than the term collective behavior was even coined.
2) Sociology: The more or less unpredictable act of people when being in group, which is totally different from the behavior they would have if acted individually.
3) Biology: A large number of group phenomena such as pattern formation, self organization, trail formation, and synchronization seen among many living creatures.

collective; → behavior.

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.


Fr.: collectivisme   

1) The principle of ownership of the means of production, by the state or the people.
2) A social system based on this principle (

collective; → -ism.


Fr.: collectivité   

1) Collective character.
2) A collective whole.

collective; → -ity.

  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.

  گرد‌آمدیدن، گرد‌آمدکردن   
gerâmadidan, gerâdmad kardan

Fr.: collectiviser   

To organize (a people, industry, economy, etc.) according to the principles of → collectivism (

collective; → -ize.

gerdâvar (#)

Fr.: collecteur   

A device that collects: a solar energy collector; a dust collector.
The semiconductor region in a bipolar junction transistor in which most of the current flows.

From → collect + -or.

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