kinematically decoupled core (KDC)
maqze-ye jonbešikâné vâjafsaridé
Fr.: cœur cinématiquement découplé
A central, tightly bound stellar subsystem observed in some elliptical galaxies which rotates in the opposite direction with respect to the main body of the → elliptical galaxy. Elliptical galaxies are thought to be the result of the → merger of two or more sizable galaxies. A plausible scenario for how counter-rotating cores could form in such a merger is as follows. If at least one of the galaxies has a core region that is fairly tightly bound by the galaxy's gravity, and the direction in which the two galaxies orbit each other before merging is opposite to the direction of rotation of stars in that tightly bound core, it is likely that, after the merger, the tightly bound core will end up as the core of the new, larger galaxy, while retaining its original sense of rotation. The surrounding stars, on the other hand, will rotate in a different way dictated by the orbital motion of the galaxies around each other, before the merger. While this is a plausible scenario, it can only explain some of the counter-rotating cores. Recently A. Tsatsi et al. (2015, ApJ 802, L3) have shown that although the two → progenitor galaxies are initially following a → prograde orbit, strong reactive forces during the merger can cause a short-lived change of their orbital spin; the two progenitors follow a → retrograde orbit right before their final coalescence. This results in a central kinematic decoupling and the formation of a large-scale (~2 kpc radius) counter-rotating core at the center of the final elliptical-like merger remnant, while its outer parts keep the rotation direction of the initial orbital spin.
The branch of mechanics dealing with the description of the motion of bodies or fluids without reference to the forces producing the motion.
From Gk. kinetikos "moving, putting in motion," from kinetos "moved," verbal adj. of kinein "to move;" PIE base *kei- "to move to and fro" (cf. Mod.Pers. šodan, šow- "to go; to become;" Av. šiyav-, š(ii)auu- "to move, go," šiyavati "goes," šyaoθna- "activity; action; doing, working;" O.Pers. šiyav- "to go forth, set," ašiyavam "I set forth;" Skt. cyu- "to move to and fro, shake about; to stir," cyávate "stirs himself, goes;" Goth. haitan "call, be called;" O.E. hatan "command, call").
Jonbešik, from jonbeš "motion" + -ik→ -ics. The first element from Mid.Pers. jumbidan, jumb- "to move," Lori, Laki jem "motion," related to gâm "step, pace;" O.Pers. gam- "to come; to go," Av. gam- "to come; to go," jamaiti "goes," gāman- "step, pace" (Mod.Pers. âmadan "to come"); Skt. gamati "goes;" Gk. bainein "to go, walk, step," L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come; PIE root *gwem- "to go, come."
Of or relating to motion; caused by motion; characterized by movement.
From Gk. kinetikos "moving, putting in motion," from kinein "to move," → kinematics.
Jonbeši, adj. of jonbeš, verbal noun of jonbidan, → move.
Fr.: énergie cinétique
The energy which a body possesses as a consequence of its motion, defined as one-half the product of its mass m and the square of its speed v, i.e. 1/2 mv2.
Fr.: hélicité cinétique
In fluid mechanics, a quantity that describes helical flow. It is defined by the integrated scalar product of the velocity field and the → vorticity: KK = ∫ dVu . (∇ x u). In the absence of magnetic field, this quantity is conserved by the → Euler equation. See also → magnetic helicity.
Fr.: potentiel cinétique
Same as → Lagrangian function.
damâ-ye jonbeši (#)
Fr.: température cinétique
The temperature of a gas defined in terms of the average kinetic energy of its atoms or molecules.
kinetic theory of gases
negare-ye jonbeši-ye gâzhâ (#)
Fr.: théorie cinétique des gaz
A theory that explains macroscopic properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion.
Fr.: diagrame de Kippenhahn
A plot representing the evolution of the internal structure of a star as a function of time. The x-axis indicates the time, the y-axis the mass, and a color or shading specifies convective regions. A vertical line through the graph corresponds to a model at a particular time.
Named after Rudolf Kippenhahn (1926-), a German astrophysicist; → diagram
qânun-e Kirchhoff (#)
Fr.: loi de Kirchhoff
The radiation law which states that at thermal equilibrium the ratio of the energy emitted by a body to the energy absorbed by it depends only on the temperature of the body.
Gustav Robert Kirchhoff (1824-1887), a German physicist who made major contributions to the understanding of electric circuits, spectroscopy, and the emission of black-body radiation from heated objects; → law.
gâfhâ-ye Kirkwood (#)
Fr.: lacunes de Kirkwood
Regions in the asteroid belt within which few asteroids are found. The Kirkwood gaps are due to the perturbing effects of Jupiter through resonances with Jupiter's orbital period.
Named for the American astronomer Daniel Kirkwood (1814-1895), who Discovered them in 1866; → gap.
Fr.: Kiso 5639
A → dwarf galaxy with a → kiloparsec size → starburst at one end, giving the system a → tadpole or → cometary shape. Also called LEDA-36252, KUG 1138+327. Its distance is 24.5 → megaparsecs (Mpc). The rotation speed of ~ 35 km s-1 combined with a radius of 1.2 kpc in the bright part of the disk implies that the corresponding → dynamical mass is 3 × 108/ sin2i Msun. This estimate is a factor of ~ 6 larger than the → stellar mass of 5 × 107 Msun from the → Sloan Digital Sky Survey photometry, but is comparable to the total → neutral hydrogen (H I) mass of ~ 3 × 108 Msun. The metallicity in the → starburst "head" appears to be less than in the rest of the galaxy (the "tail"). This peculiar pattern of metallicity, seen also in several other comparable galaxies, suggests that the starbursts in these systems were triggered by accreting a gas with lower metallicity than in the rest of the galaxy. The → Hubble Space Telescope observations of Kiso 5639 in six UV-optical and Hα filters were used to resolve the head and derive the star formation properties. The head contains 14 young → star clusters more massive than 104Msun and an overall clustering fraction for star formation of 25-40%. The Hα luminosity of the core region of the head is 8.8 ± 0.16 × 1039 erg s-1 inside an area of 3.6 × 3.6 square arcsec. The corresponding → star formation rate is ~ 0.04 Msun yr-1 (Elmegreen et al., 2018, arxiv/1805.08253, and references).
Kiso Survey of UV Bright Galaxies (Miyauchi-Isobe et al., 2010, Pub.Nat.Astro.Ob.Japan, 13, 9).
Any of several small birds of the hawk family Accipitridae that have long, pointed wings, feed on insects, carrion, reptiles, rodents, and birds, and are noted for their graceful, gliding flight (Dictionary.com).
M.E. kyte, O.E. cyta, cognate with Ger. Kauz "owl."
Zaqan "kite," of uknown origin.
Fr.: nébuleuse de Kleinmann-Law
An strong, extended infrared source in the Orion Nebula, about 1 arcminute NW of the Trapezium and about 12 arcseconds south of the → Becklin-Neugebauer object. It dominates the infrared emission at wavelengths above 20 microns. It probably represents a cluster of young and forming stars embedded in a dusty molecular cloud.
Named after Douglas E. Kleinmann (1942-) and Frank J. Low (1933-), who first studied this object in 1967; → nebula.
Fr.: Klotho, Clotho
A → main belt asteroid (97) discovered by the German astronomer Ernst W. Temple in 1868 working at Marseille Observatory.
Named after Klotho (literally "spinner") the Gk. goddess of fate who spins the thread of life, from klothein "to spin."
An electron tube for converting direct-current energy into radio frequency energy by alternately speeding up and slowing down the electrons. It is used as a microwave amplifier or oscillator in radar and high-frequency radio work.
From Gk. kluzein, klus- "to wash, break over" + -tron.
1) The joint of the leg that allows for movement between the femur and tibia and is
protected by the patella; the central area of the leg between the thigh and the lower leg.
M.E. kne; O.E. cneo, cneow "knee" (cognates: O.Norse kne, O.Sax. kneo, M.Du. cnie, Dutch knie, O.H.G. kniu, Ger. Knie; cf. Pers. zânu, as below.
Zânu "knee," Mid.Pers. šnûg "knee;" Av. žnu- "knee;" cognates: Skt. jānu-, Hittite genu "knee;" Gk. gonu "knee," gonia "corner, angle;" L. genu "knee;" O.E. cneo, as above; PIE *gnéwo-.
1) An instrument for cutting, consisting essentially of a thin,
sharp-edged, metal blade fitted with a handle.
M.E. knif; O.E. cnif, probably from O.N. knifr; cf. M.L.G. knif, M.Du. cnijf, Ger. Kneif; of uncertain origin.
Kârd "knife," from Mid.Pers. kârt "knife;" Av. karət- "to cut;" cf. Skt. kart- "to cut," karəta- "knife;" Proto-Ir. *kart- "to cut."
âzmun-e kârd (#)
Fr.: contrôle par foucaultage
The same as → Foucault knife-edge test.