An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1358
clumped wind
  باد ِ گوده‌دار   
bâd-e gudedâr

Fr.: vent grumelé   

A → radiation-driven wind of → Wolf-Rayet and → O stars, which is not homogeneous, and contains compressions and rarefactions in the form of density clumps. Observationally, wind clumping appears as moving, small-scale structures in spectral line profiles. Indirect indicators of wind clumping include: electron scattering wings of emission lines, too-weak observed UV line profiles, and shapes of X-ray lines. The most likely physical explanation for the presence of these clumps is an instability in radiatively-driven winds. The inclusion of a clumping factor in the models of W-R winds reduces the → mass loss rates by a factor ~ 2-4 relative to homogeneous models. See also → clumping factor.

clumpy; → wind.


Fr.: grumelosité   

Of a → molecular cloud, the property of being made up of → clumps.
The extent with which a molecular cloud is → clumpy.

Clumpiness, from → clumpy + → -ness.

Gudegi from gudé, → clump, + -gi suffix forming noun from adjectives ending in .


Fr.: grumelage   

The massing together of material to form clumps. → wind clumping.

clump; → -ing.

clumping factor
  کروند ِ گوده‌داری   
karvand-e gudedâri

Fr.: facteur de grumelage   

The ratio fcl = <ρ2> / <ρ >2, where ρ represents the → stellar wind density and the brackets mean values. Unclumped wind has fcl = 1 and → clumping becomes significant for fcl≅ 4.

clumping; → factor.


Fr.: grumeleux   

Of a → molecular cloud, being composed of → clumps.

Clumpy, from → clump + -y suffix meaning "full of or characterized by," from O.E. -ig, from P.Gmc. *-iga, akin to Gk. -ikos, L. -icus, → -ics.

Gudedâr, from gudé, → clump, + dâr "having, possessor," from dâštan "to have, to possess," O.Pers./Av. root dar- "to hold, keep back, maitain, keep in mind," Skt. dhr-, dharma- "law," Gk. thronos "elevated seat, throne," L. firmus "firm, stable," Lith. daryti "to make," PIE *dher- "to hold, support."

clumpy galaxy
  کهکشان ِ گوده‌دار   
kahkešân-e gudedâr

Fr.: galaxie grumeleuse   

An irregularly shaped, clumpy → star-forming galaxy that does not fall anywhere on the → Hubble sequence and appears frequently at → redshifts z ~ 1-4. Galaxies at z ≤ 1 with similar morphologies and enhanced → star formation have been identified, but become less common with decreasing redshift. Clumpy galaxies are prominent in the → early Universe.

clumpy; → galaxy.

  ۱) خوشه؛ ۲) خوشه‌بستن   
1) xušé (#); 2) xušé bastan (#)

Fr.: 1) amas; 2) s'agglomérer, se grouper   

1) A group of the same astronomical objects gathered or occurring closely together, such as → cluster of galaxies, → globular cluster, → open cluster, and so on.
2) To gather or grow into clusters. → Arches cluster, → Beehive Cluster, → bound cluster, → Brocchi's Cluster, → Bullet cluster, → Central cluster, → cluster core, → cluster mass function, → cluster of galaxies, → clustering, → clustering law, → Coma cluste, → Galactic center cluster, → galactic cluster, → galaxy cluster, → globular cluster, → Hercules cluster, → hierarchical clustering, → intercluster medium, → Local Supercluster, → moving cluster, → open cluster, → Perseus Cluster, → pre-cluster core, → protocluster, → rich cluster, → S cluster, → Sgr A* cluster, → star cluster, → super star cluster, → supercluster, → superclustering, → tight star cluster, → Trapezium cluster, → unbound cluster, → Ursa Major cluster.

O.E. clyster "cluster," probably akin to O.E. clott "clot".

Xušé "cluster, a bunch of grapes, an ear of corn," (Laki huša), from Mid.Pers. hošag or xušak; cf. Skt. guccha- "bundle, bunch of flowers, cluster of blossom, clump;" xušé bastan, with bastan "to bind, shut; to clot; to form seed buds", from Mid.Pers. bastan/vastan "to bind, shut," Av./O.Pers. band- "to bind, fetter," banda- "band, tie," Skt. bandh- "to bind, tie, fasten," PIE *bhendh- "to bind," cf. Ger. binden, E. bind.

cluster core
  مغزه‌ی ِ خوشه   
maqze-ye xušé

Fr.: cœur d'amas   

The central part of a cluster (globular, galaxies, etc.) where the spatial density of the objects making up the cluster is much higher than the average value.

cluster; → core.

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.

cluster of galaxies
  خوشه‌ی ِ کهکشانی   
xuše-ye kahkašâni (#)

Fr.: amas de galaxies   

Same as → galaxy cluster.

cluster; → galaxy.

xušé bandi

Fr.: agglomération, groupement   

Grouping of a number of similar astronomical objects.

Noun from verb → cluster.

clustering law
  قانون ِ خوشه‌بندی   
qânun-e xušé bandi

Fr.: loi de groupement   

An empirical power-law representing the number of stellar clusters as a function of the number of stars per cluster within an interval. It is expressed as: N(N*) dN*∝ N* dN*, where N(N*) is the number of clusters containing N* stars and dN* is the interval in star number. It is believed that this relationship applies to a variety of systems, including stellar clusters, globular clusters, H II regions (Oey et al. 2004, AJ 127, 1632).

clustering; → law.



A disorderly heap or assemblage; a state or condition of confusion.

Variant of clotter (now obsolete), from to clot + -er.

Âluzé, from Kurd. âluz, Tabari âluz, âliz "messy, disorderly, untidy," Dehxodâ âlofté "astonished; mad; broken," âloftan "to rage, grow mad."


Fr.: CMB   

See → cosmic microwave background radiation (CMBR).

CMB, short for → Cosmic  → Microwave  → Background.

CMB angular power spectrum
  بیناب ِ توانی ِ زاویه‌ای ِ CMB   
binâb-e tavâni-ye zâviye-yi-e CMB

Fr.: spectre de puissance angulaire du CMB   

A plot displaying the amplitude of → cosmic microwave background anisotropy as a function of angular size or → multipole index. Same as → angular fluctuation spectrum. The plot, based the on WMAP and other data, shows a plateau at large angular or length scales (→ Sachs-Wolfe plateau), then a series of peaks at progressively smaller scales. These features arise from the gravity-driven acoustic oscillations of the coupled photon-baryon fluid in the early Universe (→ baryon acoustic oscillation). In particular, a strong peak is seen on an angular scale (at l ~220), corresponding to the physical length of the → sound horizon at the → recombination era. It depends on the curvature of space. If space is positively curved, then this sound horizon scale will appear larger on the sky than in a flat Universe (the first peak will move to the left). The second peak (l ~ 550), which is the first harmonic of the main peak, relates to the baryon/photon ratio. The third peak can be used to help constrain the total matter density.

angular; → fluctuation; → spectrum.

CMB lensing
  لنزش ِ CMB   
lenzeš-e CMB

Fr.: effet de lentille du rayonnement du fond cosmique, ~ ~ du CMB   

The gravitational effect of the intervening large-scale potentials on the → cosmic microwave background radiation (CMBR). This effect smoothes out the temperature peaks and alters the statistics of the CMB.

CMB; → lensing.

CN molecule
  مولکول ِ CN   
molekul-e CN

Fr.: molécule CN   

The simplest molecule formed by the → cyano radical. The CN molecule is of considerable astrophysical importance, since many of its transition lines/bands are observed in various astronomical objects: interstellar medium, comets, various stars such as late-type F and G-dwarfs, and late-type giants. CN was the second interstellar molecule, after → CH (methylidine), to be identified; toward the bright star → Zeta Ophiuchi at ultraviolet wavelengths (A. McKellar, 1940 ASP Conf. Ser. 52, 187). CN was also one of the earliest molecules to be detected in other galaxies (Henkel et al. 1988, A&A 201L, 23).

cyano-; → molecule.


Fr.: CNO   

Referring to → carbon, → nitrogen, and → oxygen, as in → CNO cycle and → CNO star.


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