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: 12948 Search : far
spherical geometry
  هندسه‌ی ِ کُره‌ای   
hendese-ye kore-yi

Fr.: géométrie sphérique   

The branch of geometry that deals with figures on the surface of a sphere (such as the spherical triangle and spherical polygon). It is an example of a non-Euclidean geometry.

spherical; → geometry.

spherical harmonic
  هماهنگ ِ کره‌ای   
hamâhang-e kore-yi

Fr.: fonction harmonique sphérique   

A solution of some mathematical equations when → spherical polar coordinates are used in investigating physical problems in three dimensions. For example, solutions of → Laplace's equation treated in spherical polar coordinates. Spherical harmonics are ubiquitous in atomic and molecular physics and appear in quantum mechanics as → eigenfunctions of → orbital angular momentum. They are also important in the representation of the gravitational and magnetic fields of planetary bodies, the characterization of the → cosmic microwave background anisotropy, the description of electrical potentials due to charge distributions, and in certain types of fluid motion.

The term spherical harmonics was first used by William Thomson (Lord Kelvin) and Peter Guthrie Tait in their 1867 Treatise on Natural Philosophy; → spherical; → harmonic.

spherical latitude
  ورونای ِ کره‌ای، ~ سپهری   
varunâ-ye kore-yi, ~ sepehri

Fr.: latitude sphérique   

The angle between the → normal to a spherical reference surface and the → equatorial plane.

spherical; → latitude.

spherical lens
  عدسی ِ کره‌ای   
adasi-ye kore-yi

Fr.: lentille sphérique   

A lens with a refractng surface which is a portion of a sphere. Spherical lenses can be of various types: → biconvex, → biconcave, → plano-convex, → plano-concave, → concavo-convex, and → convexo-concave.

spherical; → lens.

spherical mirror
  آینه‌ی ِ کره‌ای   
âyene-ye kore-yi

Fr.: miroir sphérique   

A mirror whose reflecting surface is a portion of a sphere. Spherical mirrors can be of two types: → concave mirror and → convex mirror.

spherical; → mirror.

spherical polar coordinate
  هماراهای ِ کره‌ای ِ قطبی   
hamârâhâ-ye kore-yi-ye qotbi

Fr.: coordonnées sphériques polaires   

Same as → spherical coordinates.

spherical; → polar; → coordinate

spherical symmetry
  همامونی ِ کُره‌ای   
hamâmuni-ye kore-yi

Fr.: symétrie sphérique   

A configuration in which the constituting parts are arranged concentrically around the center of a sphere.

spherical; → symmetry.

spherical triangle
  سه‌بر ِ کُره‌ای   
sebar-e kore-yi

Fr.: triangle sphérique   

A triangle drawn on the → surface of a → sphere. A spherical triangle, like a plane triangle, may be right, obtuse, acute, equilateral, isosceles, or scalene. The sum of the angles of a spherical triangle is greater than 180° (π) and less than 540° (3π). See also → spherical excess.

spherical; → triangle.

spheroid
  کُره‌وار   
korevâr

Fr.: sphéroïde   

A body that is shaped like a sphere but is not perfectly round, especially an ellipsoid that is generated by revolving an ellipse around one of its axes.

sphere; → -oid.

spheroidal
  کره‌وار   
korevâr (#)

Fr.: sphéroïdal   

Shaped like a → spheroid.

spheroid; → -al.

spherule
  گویل   
guyel

Fr.: sphérule   

Any of many vitrified droplets of rock formed by the solidification of molten meteoritic material that flows off a meteorite during its passage through the Earth's atmosphere. Sizes range typically from 10 to 200 microns.

"Small sphere," from → sphere + diminutive suffix → -ule.

Guyel "small globe," from guy "ball, sphere" (variants golulé, gullé, goruk, gulu, gudé; cf. Skt. guda- "ball, mouthful, lump, tumour," Pali gula- "ball," Gk. gloutos "rump," L. glomus "ball," globus "globe," Ger. Kugel, E. clot; PIE *gel- "to make into a ball") + -el diminutive suffix, → -ule.

Spica (α Virginis)
  سنبله   
Sonbolé (#)

Fr.: Spica   

The brightest star in the constellation → Virgo, and the 15th brightest star in the night sky. Also known as HD 116658. It is 260 → light-years distant from Earth. A → blue giant, it is a variable → eclipsing binary, with a period of 4.014 days. Both components are → B-type stars, the → primary being a → Beta Cephei variable near to core hydrogen exhaustion (→ spectral type B1 III-IV) and the → secondary a → main sequence star (B2 V). See, e.g., R.S. Schnerr et al., 2010, arXiv:1008.4260.

From L. spica "ear of grain," related to spina "thorn," corresponding to Gk. stakhys "grapes."

Sonbolé, from sonbol "an ear of corn; a hyacinth," from Ar. sumbul.

spicule
  سیخک   
sixak

Fr.: spicule   

Any of numerous vertical → spikes of → gas visible in the → monochromatic light of certain strong → spectral lines beyond the → Sun's limb. Spicules are short-lived phenomena, corresponding to rising → jets of gas that move upward at about 30km/sec up to 10,000 km and last only about 10 minutes.

From L. spiculum "spearhead, arrowhead, bee stinger," from spica "ear of grain" + -ulum, → -ule.

Sixak, from six "spur, spit; thorn; any pointed thing."

spider vane
  پره‌ی ِ تارتن   
parre-ye târtan

Fr.: araignée   

One of, usually three or four, diagonal supports that hold the → secondary mirror in a → reflecting telescope. Also called support vane.

M.E. spithre, O.E. M.E. spithra, akin to spinnan "to spin;" cf. M.L.G., M.Du., M.H.G., Ger. spinne, Du. spin "spider;" → vane.

Parré, → vane; târtan "spider," literally "weaver," composite word of with two cognate elements, the first one târ "thread, warp, string," related to tur "net, fishing net, snare," tâl "thread" (Borujerdi dialect), tân "thread, warp of a web," from the second element tan-, tanidan "to spin, twist, weave;" Mid.Pers. tanitan; Av. tan- to stretch, extend;" cf. Skt. tan- to stretch, extend;" tanoti "stretches," tántra- "warp; essence, main point;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" Lith. tiñklas "net, fishing net, snare," Latv. tikls "net;" PIE base *ten- "to stretch."

spike
  سیخک   
sixak (#)

Fr.: pointe   

1) A long, pointed → metal  → bar.
2) Physics: A → transient variation in → voltage or → current in an → electric circuit.

M.E. spik(e) from O.N. spikr "nail;" akin to M.L.G. spiker "nail."

Sixak, from six "spur, spit; thorn; any pointed thing," + -ak a suffix of similarity and nuance.

spin
  اسپین   
espin

Fr.: spin   

1) Mechanics: The rotation of a body about an axis through the body. To cause to turn around rapidly, as on an axis. To revolve or rotate rapidly,
2) Quantum mechanics: See → spin quantum number; → spin angular momentum.

M.E. spinnen; O.E. spinnan "to draw out and twist fibers into thread" (cf. O.N., O.Fris. spinna, Dan. spinde, Du. spinnen, O.H.G. spinnan, Ger. spinnen); cognate with Pers. tan-, tanidan "to spin, twist, weave" (Mid.Pers. tanitan; Av. tan- to stretch, extend;" cf. Skt. tan- to stretch, extend;" tanoti "stretches," tántra- "warp; essence, main point;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" Lith. tiñklas "net, fishing net, snare," Latv. tikls "net;" PIE base *ten- "to stretch").

Espin, loan from E., as above.

spin angular momentum
  جنباک ِ زاویه‌ای ِ اسپین   
jonbâk-e zâviyeyi-ye espin

Fr.: moment angulaire de spin   

An intrinsic quantum mechanical characteristic of a particle that has no classical counterpart but may loosely be likened to the classical → angular momentum of a particle arising from rotation about its own axis. The magnitude of spin angular momentum is given by the expression S = ħ √ s(s + 1), where s is the → spin quantum number. As an example, the spin of an electron is s = 1/2; this means that its spin angular momentum is (ħ /2) √ 3 or 0.91 x 10-34 J.s. In addition, the projection of an angular momentum onto some defined axis is also quantized, with a z-component Sz = msħ. The only values of ms (magnetic quantum number) are ± 1/2. See also → Stern-Gerlach experiment.

spin; → angular; → momentum.

spin magnetic moment
  گشتاور ِ مغناتیسی ِ اسپین   
gaštâvar-e meqnâtisi-ye espin (#)

Fr.: moment magnétique de spin   

The magnetic moment associated with the → spin angular momentum of a charged particle. The direction of the magnetic moment is opposite to the direction of the angular momentum. The magnitude of the magnetic moment is given by: μ = -g(q / 2m)J, where q is the charge, m is the mass, and J the angular momentum. The parameter g is a characteristic of the state of the atom. It would be 1 for a pure orbital moment, or 2 for a spin moment, or some other number in between for a complicated system like an atom. The quantity in the parenthesis for the electron is the → Bohr magneton. The electron spin magnetic moment is important in the → spin-orbit interaction which splits atomic energy levels and gives rise to → fine structure in the spectra of atoms. It is also a factor in the interaction of atom with external fields, → Zeeman effect.

spin; → magnetic moment.

spin quantum number
  عدد ِ کو‌آنتومی ِ اسپین   
adad-e kuântomi-ye espin

Fr.: nombre quantique de spin   

An integer or half-integer on which the magnitude of a particle's → spin angular momentum depends. It is expressed in units of → Planck's constant divided by 2π. Called also spin, denoted s. The spin of a particle can only have a value that is zero or a multiple of 1/2. Particles with half-integer spins, 1/2, 3/2, 5/2, ..., are → fermions. Particles with integer spin (0, 1, 2, ...) are called → bosons.

spin; → quantum; → number.

spin temperature
  دمای ِ اسپین   
damâ-ye espin

Fr.: température de spin   

The → excitation temperature of the → hyperfine structure levels of the → neutral hydrogen21-centimeter line.

spin; → temperature.

<< < -es -iv -ti 21- A r abe abs abs acc acc acc act act ada adi adu aff age alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg ari art ass ast ast ast atm ato att aur aut axi B r bac Bal Bar Bar Bay bec Ber Bet Bie bij bin bio bis bla bla blu blu bol Bor bou Bra bre bro Bug C-s cal Cam can car Car Cas cat cav cel cen cer Cha cha cha che cho cir cir cir 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 coo cor cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl dar dat daw de- Deb dec dec dee def deg del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis div dog Dop dou dra dua dus dwa dyn e-m ear ecl eco eff ein Ein elb ele ele ele ele Els emi emp ene enr env epi equ equ Eri est Euc eva evo exc exc exh exo exp exp ext ext f-n Fah fam fau fee Fer fib fil fin fir fix fle flu foc for for for fra fre fre fri fun fuz gal gal gal Gan gau GCN gen geo geo geo geo Gl glo gra gra gra gra gra gre gro GW1 hab hal han HAR haz hea hel hel Hen Her heu Hig Hil hol hop hor hou Hub Hum Hyd hyd hyd hyp hys ide ign ima imp imp inc inc ind ine inf inf inf inh INP ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jos Jun K2 Kep key kin Kol lag lam Lan lar las lav lea leg len lev lig lim lin lin lin lis lob loc log lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mea mee Men mer met met met mic mid Mil min Mir mix mod mod mol mon Mor mou mul muo mys nan nat nav nec Nep neu New New NGC nob nom non non nor not nuc nuc num Nyq obj obs obs oce oen OH omn opa ope opt opt opt orb ord Ori ort osc out ove oxy pal pan par Par par par pas pea Pen per per per per per pet pha pho pho pho phy pie Pit Pla pla pla pla ple Poi pol pol pol pol pop pos pos pow pre pre pre Pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua Qui rad rad rad rad rad rad ram ran rat rea rec rec rec red ref ref reg reg rel rel rem rep res res res ret rev rho Rie rim riv rol Ros rot rul S a Sah san Sat sca Sch Sch scr sec sec sec sei sel sem sep set sha she sho sid sig sil sim sin sit sky slu sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spl spr sta sta sta sta sta ste ste sti sto str str sub sub sub sug sun sup sup sup sup sur syl syn sys tal Tay tel ten ter tex the the the thi tho thu tid tim tod top tot tra tra tra tra tri tri tro tru tur twi Typ UFO ult unc uni uni uni upg ura uti val var vec vel ver ver vig vir vis voc von wak Was wav wax wea wei whi Wie win WN6 wom X-r yel you zer zod > >>