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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Keplerian
  کپلری   
Kepleri

Fr.: keplerien   

Of or pertaining to Johannes Kepler or to his works or discoveries.

From → Kepler + -ian a suffix forming adjectives.

Keplerian angular velocity
  تندای ِ زاویه‌ای ِ کپلری   
tondâ-ye zâviye-yi-ye Kepleri

Fr.: vitesse angulaire keplérienne   

The angular velocity of a point in a circular orbit around a central mass. It is given by: ΩK = (GM/r3)1/2, where G is the → gravitational constant, M is the mass of the gravitating object, and r is the radius of the orbit of the point around the object.

Keplerian; → angular; → velocity.

Keplerian disk
  گرده‌ی ِ کپلری، دیسک ِ ~   
gerde-ye Kepleri, disk-e ~

Fr.: disque keplérien   

A circumstellar disk (such as an → accretion disk or a → protoplanetary disk) in which the → angular velocity at each radius is equal to the angular velocity of a circular → Keplerian orbit at the same radius. The main characteristic of the Keplerian disk is that → orbital velocity varies as r-1/2. This means that an object on an orbit closer to the central mass turns more rapidly than that on a farther orbit. This velocity difference is at the origin of internal friction or kinematic viscous forces between disk particles, which heats up the material.

Keplerian; → disk.

Keplerian orbit
  مدار ِ کپلری   
madâr-e Kepleri (#)

Fr.: orbit keplérienne   

The orbit of a spherical object of a finite mass around another spherical object, also of finite mass, governed by their mutual → gravitational forces only.

Keplerian; → orbit.

Keplerian orbital velocity
  تندای ِ مدار ِ کپلری   
tondâ-ye madâr-e Kepleri

Fr.: vitesse d'orbite képlérienne   

The velocity of an object orbiting another object according to → Kepler's laws.

Keplerian; → orbital; → velocity.

Keplerian rotation curve
  خم ِ چرخش ِ کپلری   
xam-e carxeš-e Kepleri (#)

Fr.: courbe de rotation keplérienne   

A → rotation curve in which the speed of the orbiting body is inversely proportional to the → square root of its distance from the mass concentrated at the center of the system.

Keplerian; → rotation; → curve.

Keplerian shear
  کرن ِ کپلری   
karn-e Kepleri

Fr.: cisaillement keplerien   

Shearing motion of an ensemble of particles, each on a nearly circular, → Keplerian orbit. → Orbital velocity decreases as orbital radius increases, yielding shear. Viscous drag on such shear, due to ring-particle collisions, plays a key role in ring processes (Ellis et al., 2007, Planetary Ring Systems, Springer).

Keplerian; → shear.

Keplerian telescope
  دوربین ِ کپلر، تلسکوپ ِ ~   
durbin-e Kepler, teleskop-e ~ (#)

Fr.: télescope de Kepler   

A → refracting telescope which has simple → convex lenses for both → objective and → eyepiece. It suffers from → chromatic aberration, which can be reduced by increasing the → focal ratio. It was first devised by Kepler in 1615.

Keplerian; → telescope.

Kerberos
  کربروس   
Kerberos

Fr.: Kerberos   

The fourth → natural satellite of → Pluto discovered in 2011 using the → Hubble Space Telescope. Also called Pluto IV (P4). It has an estimated diameter of 14-44 km, which makes it the second smallest known moon of Pluto after → Styx. Kerberos revolves around Pluto in the region between → Nix and → Hydra at a distance of about 58,000 km and makes a complete orbit roughly every 32.1 days.

Named after the three-headed dog of Greek mythology.

kernel
  ا َستل   
astel

Fr.: noyau   

1) Chemistry: The remainder of an atom after the valence electrons have been removed.
2a) Math.: 1) The set of elements that a given function from one set to a second set maps into the identity of the second set.
2b) Let A be a linear transformation of the vector space U into the vector space V . The collection of all those vectors x in U such that Ax = 0 is called the kernel of A and is denoted by ker(A).
3) Computers: The set of functions that make up the operating system, the core that provides basic services for all other parts of the operating system. → core = maqzé (مغزه); → nucleus = hasté (هسته).

Kernel, from M.E. kirnel, from O.E. cyrnel, from P.Gmc. *kurnilo- (cf. M.H.G. kornel, M.Du. cornel), from *kernan- (root of corn "seed, grain"), akin to L. granium, + -el, diminutive suffix, variant of → -al.

Astel, from asté "kernel, fruit stone," variants hasté, ostoxân "bone," from Mid.Pers. astak "fruit stone, bone," ast "bone;" Av. ast- "bone;" cf. Skt. asthi- "bone;" Gk. osteon; L. os; Hittite hashtai-; PIE base *os- + Pers. diminutive suffix -el-al.

Kerr black hole
  سیه‌چال ِ کر   
siyah câl-e Kerr (#)

Fr.: trou noir de Kerr   

A → black hole that possesses only mass (not electric charge) and rotates about a central axis. It has an → ergosphere and a → stationary limit.

Named after the New Zealand mathematician Roy P. Kerr (1934-) who, in 1963, was the first to solve the → field equationss of Einstein's theory of → general relativity for a situation of this kind; → black hole.

Kerr-Newman black hole
  سیه‌چال ِ کر-نیومن   
siyah câl-e Kerr-Newman

Fr.: trou noir de Kerr-Newman   

A rotating charged black hole. Compare with the → Kerr black hole and the → Reissner-Nordstrom black hole.

Named after Roy P. Kerr and Ezra T. Newman (1929-) who in 1963 independently found this solution to Einstein's → field equations; → black; → hole.

Kerwan
  کروان   
Kerwan

Fr.: Kerwan   

The largest → impact cratrer on → Ceres, which has a diameter of about 280 km. It is distinctly shallow for its size.

Named for The crater is named after the Hopi spirit of sprouting maize, Kerwan. The name was approved by the IAU on July 3, 2015.[1]

ket
  کت   
ket

Fr.: ket   

In Dirac's notation, a vector which describes the state of a quantum system, whether it is in a space of finite or infinite dimensions. A ket vector, written as | A >, is the dual of the → bra. Like the bra, it appears as an incomplete → bracket expression.

From -ket the second syllable in → bracket.

keV
   keV   
keV

Fr.: keV   

Kilo (thousand) → electron volt. A unit of → energy used to describe the total energy carried by a → particle or → photon.

kilo- + → electron volt.

key
  کلید   
kelid (#)

Fr.: clé   

A usually metal instrument used to operate a lock's mechanism.

M.E. key(e), kay(e), O.E. cæg "key," of unknown origin,

Kelid, variants (Tabari) kali, (Lori) kelil, (Laki) kalil "key; lock," (Kurd) kilil, kolun "latch, bolt;" Mid.Pers. kilêl "key." See also → include.

keyhole
  سوراخ ِ کلید   
surâx-e kelid (#)

Fr.: trou de serrure   

1) The hole in which a key of a lock is inserted.
2) → Keyhole Nebula.
3) A small, about 600 m wide, region of space close to the Earth where the Earth's gravity would perturb the trajectory of a passing → Near-Earth Object. The object will receive a gravitational push that will bring it back for a collision in the future. Also called resonance keyhole.

key; → hole.

Keyhole Nebula
  میغ ِ سوراخ ِ کلید   
miq-e surâx-e kelid

Fr.: Nébuleuse du Trou de Serrure   

A relatively small and dark cloud of molecules and dust seen silhouetted against the much brighter → Carina Nebula. It contains bright filaments of emitting hot gas and is roughly 7 → light-years in size.

keyhole; → nebula. The name was given by the English astronomer Sir John Herschel in the 19th century, because of the appearance of the nebula in low-resolution telescopes of that epoch.

Kiel diagram
  نمودار ِ کیل   
nemudâr-e Kiel

Fr.: diagramme de Kiel   

A version of the → H-R diagram displaying stellar gravities (→ gravity, log g) against the corresponding → effective temperatures (Teff).

Named after the group of astrophysicists (W.-R. Hamann, W. Schmutz, U. Wessolowski) working at Kiel University (Germany), who introduced the diagram in 1980s; → diagram.

Killing vector
  بردار ِ کیلینگ   
bordâr-e Killing

Fr.: vecteur de Killing   

A → vector field on a → Riemannian manifold (or → pseudo-Riemannian manifold) that preserves the → metric. In other words, the → derivative of the metric with respect to this vector field is null.

Named after the German mathematician Wilhelm Killing (1847-1923); → vector.

<< < -es -it -sc 201 951 abe abs abs aca acc acc aco act ada adh ado aer aft air Alf alg alk alp Alt alt amb ana And ang ani ann ant ant ant apo app app Apu arc arg Arn art ass ast ast ast atm ato att aur aut avo azi bac bal bar bar bat Bea Bel bet bia big bin bio Bir bla bla blo Blu bol Boo bou box bre Bri bro bur cal cal Can cap car Car cat cau cel cen cen cha Cha cha che Chi chr cir cir civ cla clo clo CMB 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 coo cor cor cor Cos cos cos cou cou cra cri cro cry cul cur cyc D l dar dat day dea dec dec dec def def deg Del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis diu dog Dop dou Dra Dsc dus dwa dyn Dys Ear ecc eco edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ eru eth Eur eve exa exc exe exi exo exp ext ext ext fab fai Fan fea fem fer fie fil fir fir fla fli flu foc for for for fra fre fre fri fun fuz gal gal gal Gam gau Gau gen geo geo geo geo Gib glo gov gra gra gra gra gre gro Gui H-a hal Ham har Hay hea hei hel Hel her het hie hig hoa hom hor hot Hub Hug hur hyd hyd hyl 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 inv ion iro Isl iso iso Jab jet Jov Jup Kar Kep kil Kip Kra Lag Lam Lan Lar las law lea Leg Leo lev lig lim lin lin lin lit loc loc log Lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal map mas mas mat Mau mea mea med Men mer Mes Met met mic mic Mie mil min Mir mix mod mol mom Moo mor mov mul mur n-b nan nat nea neg Ner neu new New NGC noc nom non non nor nor nuc nuc nul nut obj obl obs occ oct off old one ope opp opt opt orb ord org Ori osc oth ove Owl P-s Pal par par par par Pas pat pec pen per per per per per Pha pha pho pho pho phy pie pix Pla pla pla pla Pli Poi pol pol pol pol por pos pos pow pre pre pre pre pri pri pri pro pro pro pro pro pro pro pub pul pyc qua qua qua qua qui rad rad rad rad rad rad rai 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 rur S5- Sal sat sca sca Sch sci Scu sec sec sed sel sel sem seq set sha she sho sid sie sil sim sin sit sky slo sno sod sol sol sol sol son sou spa spa spe spe spe spe sph spi spo squ sta sta sta sta ste ste ste Sti sto str str sub sub sub sul sup sup sup sup sur sur syl syn sys tal Tay tel ten ter tex the the the the Tho thr tid tim Tit too Tor tra tra Tra tra Tra tri Tri tru tub tur two Typ ult ult unc uni uni uni upl ura uti val var vec vel ver Ver vie vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>