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: 13048 Search : far
Centaurus
  کنتاؤروس   
Kentâwros (#)

Fr.: Centaure   

The Centaur. A → constellation in the southern hemisphere covering an extensive area of about 1060 square degrees from R.A. 11 h to 15 h and Dec. -30° to -64°. Abbreviation: Cen, genitive form: Centauri. Centaurus is the ninth largest constellation in the sky, but it does not contain any → Messier objects. The brightest star in constellation is → Alpha Centauri which is also the third brightest star in the sky. Beta Centauri, the second brightest star in Centaurus, also called → Hadar, is the eleventh brightest star in night sky. Among other bright stars of the constellation are: Menkent (θ Cen), γ Cen, ε Cen, and η Cen. There are three → meteor showers associated with the constellation: the Alpha Centaurids, the Omicron Centaurids, and the Theta Centaurids. The constellation contains several extragalactic objects, among which: Centaurus A (NGC 5128), Omega Centauri, and NGC 5139.

L. centaurus, from Gk. kentauros, cf. Av. gandarəwa- "a mythical monster killed by Kərəsâspa," Skt. gandharva- "name of mythical beings related with Soma." In Gk. mythology, centaurs were half-man half-horse creatures living on Mount Pelion in Thessaly, northern Greece. They were followers of the wine god Dionysus and well known for drunkenness and carrying off helpless young maidens.

Kentâwros, from Gk. "Kentauros." Arabicized Qenturis (قنطورس).

Centaurus A
  کنتاؤروس A   
Kentâwros A

Fr.: Centaurus A   

The closest (3.8 ± 0.1 Mpc) → radio galaxy with a physical age of about 560 Myr, associated with the massive → elliptical galaxy NGC 5128. The nucleus harbours a → supermassive black hole, with a mass (5.5 ± 3.0) × 107 Msol derived from stellar → kinematics. A prominent → dust lane, with → starburst, crosses the central parts. Centaurus A shows a twin → jet in → radio and → X-ray bands, symmetrical on parsec scales but with evident asymmetry on kpc scales. The main (i.e. northern) jet which is markedly brighter than the counterjet, is seen at a viewing angle of approximately 50°. From photoionization models for such a viewing angle, the → Lorentz factor of the jet is derived to be ≤ 5. A large number of radio and X-ray → knots is discernible in the jet on kpc scales with the radio knots of larger proper motions showing comparatively little X-ray emission (see S. Wykes et al. 2015, MNRAS 447, 1005, and references therein).

Situated in the → Centaurus constellation.

Centaurus supercluster
  ابرخوشه‌ی ِ کنتاؤروس   
abarxuše-ye Kentawros

Fr.: superamas du Centaur   

The nearest large → supercluster. It is dominated by the → galaxy cluster A3526 (→ Abell catalog). The Centaurus supercluster is a long structure that stretches away from us. The most distant of the clusters, A3581, is about 300 million → light-years away.

Centaurus; → cluster.

center
  مرکز، کیان   
1) markaz (#), kayân (#); 2) markazidan

Fr.: 1) centre; 2) centrer   

1) The point that is equidistant from all the points on a circle or sphere.
2a) To place in or on a center.
2b) Telescope: To move a telescope in order to place the object of interest on the center of the field. → center of attraction, → center of gravity, → center of inertia, → center of mass, → center wavelength, → anticenter, → apocenter, → barycenter, → optical center, → pericenter.

M.E. centre, from O.Fr. centre, from L. centrum "center," originally fixed point of the two points of a compass, from Gk. kentron "sharp point, goad," from kentein "stitch," from PIE *kent- "to prick."

Markaz "center," from Ar.; kayân, Mod.Pers. "the point made by the compasses, that is the center of a circle" [Dehxodâ]; markazidan, infinitive from markaz, → center, + -idan infinitive suffix.

center of attraction
  مرکز ِ درکشش   
markaz-e darkašeš

Fr.: centre d'attraction   

A point toward which a force on a body is always directed.

center; → attraction.

center of gravity
  گرانیگاه   
gerânigâh (#)

Fr.: centre de gravité   

A fixed point in a body through which the resultant force of gravitational attraction acts. Same as → center of mass, → center of inertia, → centroid.

center; → gravity.

Gerânigâh, from gerânigravity + -gâh "place."

center of inertia
  گرانیگاه   
gerânigâh (#)

Fr.: centre d'inertie   

Same as → center of gravity, → center of mass, → centroid.

center; → inertia.

center of mass
  گرانیگاه   
gerânigâh (#)

Fr.: centre de masse   

Same as → center of gravity, → center of inertia, → centroid, and → barycenter.

center; → mass.

center wavelength
  موج-طول ِ مرکز   
mowjtul-e markaz

Fr.: longueur d'onde centrale   

Center of a filter passband measured at 50% of peak transmittance.

center; → wavelength.

centi-
  سانتی-   
sânti- (#)

Fr.: centi-   

Prefix denoting one-hundredth of, in metric units; e.g. centimeter, 0.01 of meter.

Fr., from L. centi,- "hundred," from centum "hundred," Gk. hekaton, Av. satem-, Mod.Pers. sad, Skt. satam-, P.Gmc. *hunda- "hundred," Goth. hund, O.H.G. hunt, O.Ir. cet, Bret. kant, PIE *kmtom "hundred."

Sânti-, from Fr., → above paragraph.

centimeter (cm)
  سانتی‌متر   
sântimetr (#)

Fr.: centimètre   

A unit of length in the → metric system, equal to one-hundredth of a meter, which is the current unit of length in the → International System of Units (SI).

centi-; → meter.

Central cluster
  خوشه‌ی ِ مرکزی   
xuše-ye markazi

Fr.: amas central   

One of the three obscured → Galactic center clusters, which contains the supermassive black hole → Sgr A*. The first stars observed in the Central cluster were evolved → massive stars showing strong He I emission lines (2.058 microns) in the near infrared K band. Subsequently more than 80 massive stars were detected including various types of → Wolf-Rayet stars, as well as → O-type and → B-type → supergiants and → dwarfs (see, e.g. Martins et al. 2007, A&A 468, 233).

central; → cluster.

central eclipse
  گرفت ِ مرکزی   
gereft-e markazi

Fr.: éclipse centrale   

An eclipse during which the axis of the lunar shadow cone intersects the Earth's surface (in the case of solar eclipses) or the axis of the terrestrial shadow cone intersects the Moon's surface (in the case of lunar eclipses). The total and annular solar eclipses are usually central. They can also be not central; then, they are visible only from places situated at high latitudes (M.S.: SDE).

central force
  نیروی ِ مرکزی   
niru-ye markazi

Fr.: force centrale   

A → force that is always directed toward a fixed point and whose → magnitude depends only on the distance from that point. Mathematically, F is a central force if and only if: F = f(r)r1 = f(r)r/r, where r1 = r/r is a unit → vector in the direction of r. If f(r) < 0 the force is said to be → attractive toward the source. If f(r) > 0 the force is said to be → repulsive from the source. In other words, a central force is one whose → potential, V(r), depends only on the → distance from the source. → Gravitational force and → electrostatic force are central, with V(r)∝ 1/r.

central; → force.

central limit theorem
  فربین ِ حد ِ مرکزی   
farbin-e hadd-e markazi

Fr.: théorème central limite   

A statement about the characteristics of the sampling distribution of means of → random samples from a given → statistical population. For any set of independent, identically distributed random variables, X1, X2,..., Xn, with a → mean μ and → variance σ2, the distribution of the means is equal to the mean of the population from which the samples were drawn. Moreover, if the original population has a → normal distribution, the sampling distribution of means will also be normal. If the original population is not normally distributed, the sampling distribution of means will increasingly approximate a normal distribution as sample size increases.

central; → limit; → theorem.

Central Molecular Zone (CMZ)
  زنار ِ مولکولی ِ مرکزی   
zonâr-e molekuli-ye markazi

Fr.: zone moléculaire centrale   

A vast, turbulent region encircling the → Milky Way's nucleus that contains a large fraction of the → Galaxy's dense → molecular clouds and → star formation regions. Spanning -1 to +1.5 degrees of → Sgr A*, the CMZ is about 400 pc × 100 pc in size and contains at least 107solar masses of → giant molecular clouds, approximately 10% of the Galaxy's molecular gas. The gas in the CMZ is at higher temperature than typical giant molecular clouds and has high velocity dispersion reflecting the → turbulent nature of the gas in the area. Despite these extensive molecular reserves, the → star formation rate within the CMZ is actually lower than expected based on the analysis of nearby → star-forming regions in the quiescent → Galactic disk. A common assumption is that this is a result of the extreme conditions within the CMZ, where the density, pressure, temperature, → velocity dispersion and → radiation field are all significantly greater than elsewhere in the Milky Way (Clark et al. 2018, The Messenger 173, 22 and references therein).

central; → molecular; → zone.

central peak
  ستیغ ِ مرکزی   
setiq-e markazi

Fr.: pic central   

The uplift of the central parts of the → crater floor due to the impacting force of a large → meteorite. The shock wave entering the Earth will first move in as a compressional wave (P-wave), but after passage of the compressional wave an expansion wave (rarefaction wave) will move back toward the surface. This will cause the floor of the crater to be uplifted and may also cause the rock around the rim of the crater to bent upward.

central; → peak.

central processing unit (CPU)
  یکای ِ آمایش ِ مرکزی   
yekâ-ye âmâyeš-e markazi

Fr.: unité centrale de traitement   

The primary component of a → computer that processes instructions. It runs the → operating system and → applications, constantly receiving input from the user or active → software programs. The CPU has two typical components: 1) Control Unit, which extracts instructions from memory and decodes and executes them. 2) Arithmetic Logic Unit (ALU), which handles arithmetic and logical operations.

central; → processing; → unit.

central uplift
  بالامد ِ مرکزی   
bâlâmad-e markazi

Fr.: pic central   

Same as → central peak.

central; → up; → lift.

central; → uplift.

central wavelength
  موج-طول ِ مرکزی   
mowjtul-e markazi

Fr.: longueur d'onde centrale   

1) In an interference filter, the wavelength of peak transmission.
2) In a spectrograph, the wavelength corresponding to the middle of the range covered by the grating or grism.

Central, adj. from → center; → wavelength.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara Arc ari Arr ash ass ast ast asy atm ato att aut ave axi Bab bal Bal bar bar bea Bek Bes bia Big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo cal cal can cap car Car cat cat CCD Cen cen CH cha cha che Che chr cir cir cit cla clo clo clu Coa coe coh col col col com com com com com com com com Com con con con con con con con con con con con con Cop Cor cor cor cos cos cou cou Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp opt opt orb ord ori ort osc out ove oxi pai pan par par par par pas pea pen per per per per Per per pha phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar ray rea rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>