The process by which craters form on the surface of Solar System objects.
From lâvak or kandâl, → crater, + zâyi from zâ- present tense stem of zâdan "to give birth," Mid.Pers. zâtan, Av. zan- "to bear, give birth to a child, be born," infinitive zazâite, zâta- "born," cf. Skt. janati "begets, bears," L. gignere "to beget," PIE base *gen- "to give birth, beget."
Fr.: anneau de crèpe
An alternative name for Saturn's C ring, which is a wide but faint ring located inside the B Ring. Discovered in 1850 by William and George Bond, it was termed "crepe" because it seemed to be composed of darker material than the brighter A and B Rings.
Crepe, from Fr. crêpe, from O.Fr. crespe, from L. crispa, fem. of crispus "curled;" → ring.
Halqé, → ring; parniyân "a kind of fine painted silk, a mantle of such silk."
Fr.: anneau D
Taking or willing to take risks; audaciousness.
fariz-e târik (#)
Fr.: frange noire
One of the successive dark and light bands produced by diffraction or interference of light.
From O.Fr. frange, from V.L. *frimbia alteration by metathesis of L. fimbria "fringe, edge of garment."
Fariz, variants farviz, farâviz "fringe, edge of garment."
Verbal noun of → deblur.
diamond ring effect
oskar-e angoštar-e almâs
Fr.: effet anneau de diamant
An intense flash of light that happens a few seconds before and after totality during a solar eclipse. The effect is caused by the last rays of sunlight before totality (or the first rays of sunlight after totality) shining through valleys on the edge of the Moon.
Oskar, → effect; angoštar "a ring worn on the finger," from angošt "finger," Mid.Pers. angušt "finger, toe," Av. angušta- "toe," from ank- "curved, crooked," cf. Skt. angustha- "thumb," ankah "hook, bent," Gk. angkon "elbow," angkura "anchor," L. angulum "corner" (E. angle), Lith. anka "loop," O.E. ancleo "ankle," O.H.G. ango "hook," PIE base *ang-/*ank- "to bend"; → diamond.
double Compton scattering
parâkaneš-e Compton-e dotâyi
Fr.: diffusion Compton double
An electron-photon interaction that can be thought of as a → Compton scattering event associated with the production or destruction of an extra photon.
In the course of, in the time of, throughout the continuance of.
M.E. Duryng, durand, pr.p. of duren "to last, endure, continue, be or exist," from O.Fr. durer, from L. durare "to harden," from durus "hard;" PIE root *deru- "be firm, solid, steadfast."
parâkaneš-e qobâri, ~ pat qobâr
Fr.: diffusion par la poussière
Fr.: anneau E
Fr.: anneau d'Einstein
The apparent shape of a background source unsergoing the effect of → gravitational lensing as seen from Earth, provided that the source, the intervening lens, and the observer are in perfect alignement through → Einstein radius.
Fr.: diffusion élastique
In a → collision between two → particles,
the reaction in which the total → kinetic energy
of the system, projectile plus target, is the same before the collision as after.
bâl-e parâkaneš-e elektron
A → line broadening phenomenon involving the scattering effect of → free electrons on the → radiation transfer in → stellar atmospheres. The scattering of radiation by free electrons plays an important role in the atmospheres of → hot stars, such as → O-types, early → B-types, and → Wolf-Rayet stars. The first detailed study of electron scattering in Wolf-Rayet stars was by Castor et al. (1970), who used electron scattering to explain the broad emission wings of N IV λ3483 in HD 192163. In → P Cygni stars the explanation of the very extended (almost symmetric) wings on the → Balmer lines as caused by electron scattering was first made by Bernat & Lambert (1978). Hillier (1991) showed that significant reduction in the strength of an electron-scattering wing can be achieved in a model of → clumped wind for a lower mean → mass loss rate. This resulted in a better agreement between observations and theoretical predictions. Electron-scattering wings provide diagnostics regarding the presence of density inhomogeneities in → stellar winds (Münch, 1948, ApJ 108, 116; Hillier, 1991, A&A 247, 455).
The action, work, or profession of an engineer.
Fr.: anneau F
Figuring, noun of → figure.
Šekldahi, "giving form," from šekl, → figure + dahi, a verbal noun of dâdan "to give," from Mid.Pers. dâdan "to give," O.Pers./Av. dā- "to give, grant, yield," dadāiti "he gives;" cf. Skt. dadáti "he gives," Gk. didomi "I give," tithenai "to put, set, place;" L. dare "to give, offer;" facere "to do, to make;" Rus. delat "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do." PIE base *dhe- "to put, to do."
A weak yet important kind of mixing that results from → fingering instability in stars within → radiative zones that have an unstable mean → molecular weight → gradient. Also called → thermohaline convection.
Fr.: instabilité à traines
A type of instability that often occurs in fluids which are thermally stably stratified, but have an inhomogeneous composition. A well-known example, found in upper layers of the Earth's oceans, is → salt fingers. Similar fingering instabilities can occur in any other thermally stably stratified solution, provided the concentration of the slower-diffusing solute increases with height. The saturated state of this instability, → fingering convection, takes the form of tightly-packed, vertically-elongated plumes of sinking dense fluid and rising light fluid, and significantly enhances the vertical transport of both heat and chemical composition. The fingering instability occurs in stars within radiation zones that have an unstable mean → molecular weight → gradient (μ gradient). This situation is often found as a result of material accretion onto a star by anything from a single or multiple planets, to material from a dust-enriched or debris accretion disk, or material from a more evolved companion. It also naturally arises in the vicinity of the → hydrogen shell burning in → red giant branch (RGB) stars, and in thin element-rich layers near the surface of intermediate-mass stars. The fingering instability initially takes the form of thin tubes, hence the name "finger," within which the fluid moves vertically. The tubes rapidly break down, however, as a result of parasitic shear instabilities that develop inbetween them, and the fingering instability eventually saturates into a state of homogeneous fingering convection where the typical aspect ratio of the eddies is closer to one (P. Garaud et al., 2015, arXiv:1505.07759).
Fr.: diffusion en avant
Scattering in which photons emerge from the → scattering medium travelling predominantly in the same direction as they entered. The → halos around the Sun and Moon in wet weather are caused by forward scattering by water droplets in the Earth's atmosphere. → backscattering.