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sayârak-e gune-ye C
Fr.: astéroïde de type C
An → asteroid that belongs to the family of → carbonaceous asteroids. They are → depleted in → hydrogen and → helium, have chemical ratios akin to solar composition, and show low → albedo (0.03-0.09). C-type asteroids are the most common variety, forming around 75% of known asteroids. They inhabit → main belt's outer regions.
The Sculptor's Chisel. A small inconspicuous → constellation in the southern sky, representing a sculptor's chisel. Its brightest star, Alpha Caeli, is magnitude 4.5. Approximate position: R.A. 4.5 h, Dec.: -40°; abbreviation: Cae, genitive form Caeli.
L. caelum sculptor's "chisel."
Qalam "chisel," from Ar., related to L. caelum?
M.E. from O.Fr. cage, from L. cavea "hollow place, enclosure for animals," cognate with Pers. kâv "hollow," → concave.
Qafas "cage," of unknown origin.
šaxâne-ye CAI, šahânsang-e ~
Fr.: météorite de type CAI
A member of a group of tiny (millimeter to centimeter) light-colored meteorites found often with → chondrules. They consist of high vaporization minerals, including → silicates and → oxides of Ca, Al, and Ti, but are quite poor in Fe. Compared to common → chondrules, which are uniformly spherical, their shapes are less regular. They appear to be 2-3 million years older than chondrules. CAI meteorites are probably the oldest solid materials to have formed in the → solar nebula.
Fr.: modèle CAK
The standard model of → radiation-driven winds in which the acceleration of → stellar wind is provided by the → absorption and → scattering of ultraviolet photons in ions of abundant elements (→ CNO, → iron peak) in the → Lyman continuum. The model was developed by Castor et al. (1975), who assumed that the forces due to the radiative lines and the pressure gradients are functions of local velocity gradient, and used a large number (~ 105) of lines which have a statistical distribution in line strengths. The model led to predictions of → mass loss rates (M_dot) and terminal velocities as a function of stellar properties and the line statistics parameters. With the modifications by Friend and Abbott (1986), Pauldrach et al. (1986), and Kudritzki et al. (1989), CAK multi-line theory gives good agreement with observationally derived values of mass loss rate and → terminal velocity (v∞). CAK wind solutions predict the terminal velocity to be proportional to the → escape velocity and the mass loss rate to depend strongly on the stellar → luminosity. Observations over the past decades have shown that these main wind parameters, M_dot and v∞, indeed behave as predicted by CAK. This basic agreement between observations and theory provides strong evidence that the winds from → massive stars are driven by → radiation pressure and this has favored the CAK formalism. See also → multiple scattering. See the review by J. Puls et al. 2008, Astron. Astrophys. Rev. 16, 209.
CAK, the initials of the researchers who developed the model: J.I. Castor, D.C. Abbott, and R.I. Klein(1975, Radiation-driven winds in Of stars, ApJ 195, 157); → model.
Fr.: nébuleuse de l'œuf pourri
A → bipolar nebula and → OH/IR source with technical designation OH 231.8+4.2. It is a → proto-planetary nebula (PPN) 1.4 → light-years long and located some 5,000 light-years from Earth in the constellation → Puppis. The obscured → central star, named QX Pup, is classified as M9-10 III and has a → Mira-like variability consistent with an evolved → asymptotic giant branch (AGB) star. The late evolution of this object may have been complex since it has a binary → companion star (of type A0 V) that has been indirectly identified from analysis of the spectrum of the hidden central source reflected by the nebular dust. The system has a total luminosity of ~ 104 Lsun and its systemic velocity relative to the → Local Standard of Rest is VLSR ~ 34 km s-1. OH 231.8+4.2 is very likely a member of the → open cluster M46 with a progenitor mass of ~ 3 Msun. The nebula is also known as the Rotten Egg Nebula because it contains a lot of sulphur, an element that, when combined with other elements, smells like a rotten egg (see, e.g., Prieto et al., 2015, A&A, 575, A84).
The name "Calabash Nebula" was first proposed by Icke & Preston, 1989, A&A, 211, 409. It refers to the apparent form of the object which resembles a calabash "a tree that has large, rounded gourdlike fruit; the fruit of any of these plants," from Sp. calabaza, possibly from Ar. qar'ah yâbisah "dry gourd," from Pers. kharabuz, used of various large melons; → nebula.
A metallic chemical element; symbol Ca. → Atomic number 20; → atomic weight 40.08; → melting point about 839°C; → boiling point 1,484°C; → specific gravity 1.55 at 20°C; → valence +2. It is fifth in abundance in the Earth's crust, of which it forms more than 3%. It is an essential constituent of leaves, bones, teeth, and shells. Never found in nature uncombined, it occurs abundantly as limestone, gypsum, and fluorite. Calcium has several radioactive isotopes. It was first isolated by the British chemist Humphry Davy in 1808.
Fr.: coupure de calcium
A discontinuity in the spectrum of galaxies near the Ca II → H and K lines at about 4000 Å. The Ca break is the most prominent feature in the spectra of elliptical galaxies. Its strength is given by the → calcium break index.
calcium break index
dišan-e gosast-e kalsiom
Fr.: indice de la coupure de calcium
The strength of the → calcium break, as measured from the fluxes in the intervals 3750-3950 Å and 4050-4250 Å. It is given by the expression Ca-break[%] = 100 · (fupper - flower)/fupper, where fupper and flower are the mean fluxes measured in the 3750-3950 Å and 4050-4250 Å bands, respectively, in the rest frame (Dressler & Shectman 1987, AJ 94, 899).
Calculate, from L.L. calculare, calculat-, from L. calculus "small stone, pebble" (used in reckoning), dim. of calx, calc- "limestone," from Gk. khalix "small pebble," kakhlex "round pebble,"cf. O.E. hægl, hagol "hale," from W.Gmc. *haglaz, O.H.G. hagal, O.N. hagl, Ger. Hagel "hail", PIE *kaghlo- "pebble, hail." The Pers. cognate is probably the Lori hogela "big stone."
Afmârdan, from prefix af- + stem mar- + infinitive suffix -idan. The Mod.Pers. prefix af- "to, up, upon," occurring in several words (e.g. afzudan, afruxtan, afsar, afsâr, afqân), derives from O.Pers./Av. abiy-/aiwi- "to, upon, against;" cf. Skt. abhi-, Gk. amphi-. The stem mar-, mâr- "count, reckon, measure," which occurs in several Mid./Mod.Pers. terms (e.g. ošmârdan, šomârdan, šomordan "to count, to calculate," âmâr "computation, arithmetic; statistics," âmârdan "to reckon, to calculate," bimar "countless," nahmâr "great, large, big"), is related to the Av. base mar- "to have in mind, remember, recall," hišmar-; cf. Skt. smr-, smarati "to remember, he remembers," L. memor, memoria, Gk. mermera "care," martyr "witness."
The act, process, or result of calculating.
Calculation, noun from → calculate.
Afmâreš, verbal noun from afmârdan→ calculate.
A small electronic device that performs calculations.
Afmârgar, from afmâr→ calculate + -gar agent suffix, from kar-, kardan "to do, to make" (Mid.Pers. kardan, O.Pers./Av. kar- "to do, make, build," Av. kərənaoiti "makes," cf. Skt. kr- "to do, to make," krnoti "makes," karma "act, deed;" PIE base kwer- "to do, to make").
Fr.: calcul différentiel et intégral
L. calculus "small stone," from calx, calcis "limestone," → calculate, + -ulus diminutive suffix, → -ule.
calculus of finite differences
afmârik-e degarsânihâ-ye karânmand
Fr.: calcul des différences finies
calculus of probabilities
Fr.: calcul des probabilités
A branch of mathematics that deals with the calculation of the probabilities of events.
calculus of residues
Fr.: calcul des résidus
The application of → Cauchy's theorem to compute residues and poles, evaluate contour integrals, sum infinite series, and carry out related calculations.
calculus of tensors
Fr.: calcul tensoriel
The branch of mathematics dealing with the differentiation of tensors.
calculus of variations
Fr.: calcul des variations
The study of maximum and minimum properties of → definite integrals.
calculus of vectors
Fr.: calcul vectoriel
The area of calculus dealing with differentiation and integration of vector-valued functions; a sub-area of tensor calculus.
A large, roughly circular, → crater with diameter at least three or four times depth on the summit or in the side of a → volcano. A caldera can form from a volcanic blast or the collapse of a volcanic cone into an emptied → magma chamber.
From Sp. caldera "cauldron, kettle," also name of a crater on Canary Islands, from L. caldarius "of warming," from calidus "warm, hot," → calorie.
Tiyân "large cauldron; cauldron used for warming water in a communal bathhouse," of unknown origin.