An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

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

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.

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.

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.

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.

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.
2) Something resembling a bent knee, especially a rigid or braced angle between two framing members (Dictionary.com). → alpha element knee

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.
2) Any blade for cutting, as in a tool or machine (Dictionary.com).

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."

The same as → Foucault knife-edge test.

→ knife; → edge; → test.

1) To perceive or understand as fact or truth; to apprehend clearly and with certainty.
2) To have established or fixed in the mind or memory (Dictionary.com).

M.E. knowen, knawen, from O.E. cnâwan, akin to O.H.G. bichnâan "to recognize," L. gnoscere, noscere "to come to know," Gk. gignoskein, Pers. šenâxtan, dânestan, as below.

Dânestan "to know;" Mid.Pers. dânistan "to know;" variant šenâxtan, šenâs- "to recognize, to know" (Mid.Pers. šnâxtan, šnâs- "to know, recognize"); O.Pers./Av. xšnā- "to know, learn, come to know, recognize;" cf. Skt. jñā- "to recognize, know," jānāti "he knows;" Gk. gignoskein "to know, think, judge," cognate with L. gnoscere, noscere "to come to know" (Fr. connaître; Sp. conocer); P.Gmc. *knoeanan; O.E. cnawan, E. know, as above; Rus. znat "to know;" PIE base *gno- "to know."

1) Acquaintance with facts, truths, or principles, as from study or investigation.
2) All the information, facts, truths, and principles learned throughout time.

M.E. cnawlece, from O.E. cnawan, cf. O.H.G. bi-chnaan, ir-chnaan "to know;" cognate with Pers. šenâxt, as below.

1) Šenâxt, past stem of šenâxtan, šenâsidan "to know, discern, distinguish, be acquainted with;" Mid.Pers. šnâxtan, šnâs- "to know, recognize," dânestan "to know;" O.Pers./Av. xšnā- "to know, learn, come to know, recognize;" cf. Skt. jñā- "to recognize, know," jānāti "he knows;" Gk. gignoskein "to know, think, judge;" L. gnoscere, noscere "to come to know" (Fr. connaître; Sp. conocer); O.E. cnawan; E. know; Rus. znat "to know;" PIE base *gno- "to know."
2) Dânestgân, literally "body of (what is) known," from dânest, short for dâneste "known," p.p. of dânestan variant of šenâxtan, as above, + -gân suffix forming plural entities.

The thin layer of → vapor immediately adjacent to an irradiated surface. The thickness of the Knudsen layer is generally recognized to be in the order of a few → mean free paths from the surface.

Named after Danish physicist Martin Knudsen (1871-1949); → layer.

The second brightest star in the constellation → Ursa Minor. It is a reddish, evolved → giant of → spectral type K4 with a visual magnitude of 2.1. It is almost 500 times more luminous than the Sun and lies at a distance of 126 light years. Also called Kocab, Kochah.

Kochab, from Ar. al-Kaukab (الکوکب) "star," shortened from al-Kaukab al-shemali (الکوکب الشمالی) "North Star."

The proportionality constant C in Kolmogorov's mathematical analysis of → turbulence which states that the spectral energy E(k) in the range of turbulent scales is E(k) =C ε^2/3 k^-5/3, where k represents the → wave number (inversely proportional to the wavelength or → eddy size), and ε is the average energy dissipation per unit mass in the fluid. Experimental measurements give C close to 1.5.

Andrei Nikolaevich Kolmogorov (1903-1987), a prominent Soviet mathematician, who made major advances in different scientific fields, mainly probability theory, topology, turbulence, classical mechanics, and computational complexity; → constant.

Length scale of → turbulent flow below which the effects of molecular → viscosity are non-negligible.

→ Kolmogorov constant; → scale.

The distribution of energy over different scales in a → turbulent flow where → energy cascade occurs. Let E be the energy per unit → wave number (k) and ε the energy → dissipation parameter, E = E(k,ε). → Dimensional analysis yields: E = Cε^2/3k^-5/3, where C is the → Kolmogorov constant.

A. N. Kolmogorov, 1941, Local structure of turbulence in an incompressible fluid for very large Reynolds numbers, Doklady Acad Sci. USSR 31, 301; → spectrum.

An ice-filled → impact crater located in the northern lowlands of Mars at 73° north latitude and 165° east longitude, south of the large Olympia Undae dune field that partly surrounds Mars' north polar cap. Korolev crater is 82 km across with its centre hosting a mound of water ice some 1.8 kilometres thick all year round. The reason for the permanently stable water ice in the crater is because its deepest part acts as a natural cold trap. The air above the ice cools and is thus heavier compared to the surrounding air: since air is a poor conductor of heat, the water ice mound is effectively shielded from heating and sublimation.

The crater is named after chief rocket engineer and spacecraft designer Sergei Korolev (1907-1966), dubbed the father of Soviet space technology.

In the → three-body problem, the → perturbation of the orbit of a → secondary body by the garvity of a third body located at a distance much larger than the separation between the → primary body and the secondary. The secondary's orbit oscillates about a constant value involving a periodic exchange between the extreme values of its → inclination and orbital → eccentricity. The Kozai-Lidov mechanism results from the conservation of the quantity (1 - e²)^1/2.cos i for each component, where e is eccentricity and i is inclination. The total → angular momentum of the system remains constant while the angular momentum is exchanged betwwen the components. It has been suggested that the Kozai mechanism is responsible for the high eccentricities observed in the orbits of → extrasolar planets. If the parent star has a massive yet unseen substellar companion, orbiting at a great distance, and in an orbit highly inclined to the plane of the planets' orbits, the mechanism should induce high eccentricities into the orbits of the planets. Similarly, this mechanism may be responsible for the high eccentricities observed in the orbits of many → Kuiper Belt Objects such as 2003 UB313.

Named for the japanese Yoshihide Kozai (1962, Astronomical J. 67, 591), and the Russian Michael Lidov (1962, Planetary & Space Science 9, 719).