Kepler spacecraft teleskop-e fazâyi-ye Kepler Fr.: télescope spatial de Kepler A → NASA space telescope launched in March 2009 to discover Earth-size planets using the → transit method. The telescope has a diameter of 0.95 m and its only instrument is a → photometer that continuously monitors the brightness of over 145,000 → main sequence stars in a fixed field of view of 115 deg^{2} (about 12° diameter). The expected mission lifetime is 3.5 years extendible to at least 6 years. In honor of Johannes → Kepler; → spacecraft. |
Kepler's equation hamugeš-e Kepler Fr.: équation de Kepler An equation that enables the position of a body in an elliptical orbit to be calculated at any given time from its orbital elements. It relates the → mean anomaly of the body to its → eccentric anomaly. |
Kepler's first law qânun-e naxost-e Kepler (#) Fr.: première loi de Kepler Planets move in elliptical paths, with the Sun at one focus of the ellipse. |
Kepler's laws qânunhâ-ye Kepler (#) Fr.: lois de Kepler 1) The planets move about the Sun in ellipses, at one focus of which the Sun is situated. |
Kepler's second law qânun-e dovom-e Kepler (#) Fr.: deuxième loi de Kepler A line joining a planet to the Sun sweeps out equal areas in equal intervals of time. |
Kepler's star setâre-ye Kepler (#) Fr.: étoile de Kepler A → supernova in → Ophiuchus, first observed on 1604 October 9, and described by Johannes Kepler in his book De stella nova (1606). It reached a maximum → apparent magnitude of -3 in late October. The star remained visible for almost a year. The → light curve is that of a → Type Ia supernova. The → supernova remnant consists of a few filaments and brighter knots at a distance of about 30,000 → light-years. It is the radio source 3C 358. Also known as SN 1604 and Kepler's supernova. |
Kepler's third law qânun-e sevom-e Kepler (#) Fr.: troisième loi de Kepler The ratio between the square of a planet's → orbital period (P) to the cube of the mean distance from the Sun (a) is the same for all planets: P^{2}∝ a^{3}. More accurately, P^{2} = (4π^{2}a^{3}) / [G(M_{1} + M_{2})], where M_{1} and M_{2} are the masses of the two orbiting objects in → solar masses and G is the → gravitational constant. In our solar system M_{1} = 1. The → semi-major axis size (a is expressed in → astronomical units and the period (P) is measured in years. |
Keplerian 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 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: Ω_{K} = (GM/r^{3})^{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 disk 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 orbit 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 rotation curve 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 shear 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 telescope 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. |
Kerberos 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 astel Fr.: noyau 1) Chemistry: The remainder of an atom after the valence electrons have
been removed. 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 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 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 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 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. |