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: 3079 Search : on
Clausius equation
  هموگش ِ کلاؤزیوس   
hamugeš-e Clausius

Fr.: équation de Clausius   

A first-order improvement on the → ideal gas law that corrects for the finite volume of molecules.

After Rudolf Clausius (1822-1888), a German physicist and mathematician, → equation.

Clausius-Clapeyron equation
  هموگش ِ کلاؤزیوس-کلاپرون   
hamugeš-e Clausius-Clapeyron

Fr.: équation de Clausius-Clapeyron   

An approximation of the → Clapeyron equation for liquid-vapor equilibrium that incorporates the → ideal gas law and states that the logarithm of vapor pressure is inversely proportional to temperature.

Clausius equation; → Clapeyron equation.

cloud fragmentation
  لتپارش ِ ابر   
latpâreš-e abr

Fr.: fragmentation de nuage   

Process by which a → collapsing → giant molecular cloud breaks into dense → clumps, eventually bringing about → pre-stellar cores.

cloud; → fragmentation.

cluster formation efficiency (CFE)
  کارایی ِ دیسش ِ خوشه   
kârâyiè-ye diseš-e xuše

Fr.: efficacité de formation d'amas   

The fraction of → star formation which happens in → bound clusters. It is defined as the ratio between the → cluster formation rate and → star formation rate (Bastian, 2008, MNRAS 390, 759, arxiv/0807.4687).

cluster; → formation; → efficiency.

cluster formation rate (CFR)
  نرخ ِ دیسش ِ خوشه   
nerx-e diseš-e xuše

Fr.: taux de formation d'amas   

A parameter used in star formation models representing the ratio of the total mass in → star clusters to the corresponding age range (Bastian, 2008, MNRAS 390, 759, arxiv/0807.4687).

cluster; → formation; → rate.

cluster mass function (CMF)
  کریای ِ جرم ِ خوشه   
karyâ-ye jerm-e xušé

Fr.: fonction de masse d'amas   

An empirical power-law relation representing the number of clusters as a function of their mass. It is defined as: N(M)dM ∝ MdM, where the exponent α has an estimated value of about 2 and dM is the mass interval. It is believed that this is a universal law applying to a variety of objects including globular clusters, massive young clusters, and H II regions.

cluster; → mass; → function.

CO formation
  دیسش ِ CO   
diseš-e CO

Fr.: formation de CO   

The chemical reaction that gives rise to → carbon monoxide in the → interstellar medium. According to models, several processes may lead to CO formation. For example, HCO+ + e → CO + H. The molecule HCO+ is itself produced through several paths, for example: H3+ + C → CH2+ + H, CH2+ + H2 → CH3+ + H, CH3+ + O → HCO+ + H. Alternatively: C+ + H2O → HCO+ + H. Another possibility: C+ + OH → CO+ + H, CO+ + H2→ HCO+ + H.

carbon monoxide; → formation.

co-orbital motion
  جنبش ِ هم‌مداری   
jonbeš-e ham-madâri

Fr.: mouvement co-orbital   

The motion of two or more bodies around the Sun on different orbits when it takes them the same amount of time to complete one revolution. There are three possible types of co-orbital motions of a small body associated with a planet: → tadpole orbits, → horseshoe orbits, and → quasi-satellite orbits.

co-orbital; → motion.

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.

coagulation
  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.

Cocoon Nebula (IC 5146)
  میغ ِ پیله   
miq-e pilé

Fr.: nébuleuse du cocon   

An emission nebula located about 3,000 light-years away toward the → constellation  → Cygnus. It is thought to be a region of active → star formation.

Cocoon, from Provençal Fr. coucoun, from O.Fr. coque "egg shell, nut shell," L. coccum "berry," from Gk. kokkos "berry, seed;" → star; → nebula.

Miq, → nebula; pilé "the silkworm's cocoon; a purse", cf. Skt. patta- "woven silk."

cocoon star
  ستاره‌ی ِ پیله‌ای   
setâre-ye pileyi

Fr.: étoile dans son cocon   

A star hidden in a dense envelope of gas and dust which is a strong source of infrared emission.

Cocoon nebula; → star.

codeclination
  هم‌واکیلش   
hamvâkileš

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.

coercion
  پزورش   
pazureš

Fr.: coercition   

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

Verbal noun of → coerce.

cognition
  شناختار   
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. (Dictionary.com).

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."

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.

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.

collaboration
  همکاری   
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.

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