Fr.: desexcitation finale
The last stage of → merger between two → black holes undergoing → inspiral. At the end of the evolution of a → binary black hole system, the black holes get close enough to → merge together into a single, larger black hole (→ black hole merger). The resulting black hole is at first distorted and asymmetric, but in the ringdown process the black hole's vibrations decay due to → gravitational radiation leaving finally a quiescent, spinning black hole.
M.E. ring, from O.E. hringan; akin to O.Norse hringja "to ring;" → down.
1) A small ring.
halqehâ-ye Keyvân (#)
Fr.: anneaux de Saturne
A system of rings around Saturn made up of countless small particles, ranging in size from micrometers to meters, that orbit the planet. The ring particles are made almost entirely of → water ice, with some contamination from → dust and other chemicals. The ring system is divided into six major components: D, C, B, A, F, and G rings, listed from inside to outside. But in reality, these major divisions are subdivided into thousands of individual → ringlets. The large gap between the A and B rings is called the Cassini division. Saturn's rings are extraordinarily thin: though they are 250,000 km or more in diameter, they are less than one kilometer thick. → A ring, → B ring, → C ring, → D ring, → F ring, → G ring.
The process in which the direction of motion of → particles
or → waves is changed randomly because of their
→ interactions (→ collisions)
with other particles of the → medium transversed.
Verbal noun of → scatter.
Fr.: angle de diffusion
The angle between the → incident radiation on a → particle (such as a water droplet in a rainbow) and the scattered radiation (such as the light ray leaving the droplet). Scattering angle is a function of → impact parameter. In other words, The angle along which the change of direction has taken place, irrespective whether radiation is scattered by particles or reflected (refracted) by a surface.
Fr.: coefficient de diffusion
The fraction of light scattered per unit distance in a medium.
scattering of stars
Fr.: diffusion des étoiles
The progressive increase of random motions of → disk stars with increasing stellar → ages. While some initial random motion seems likely in the disturbed conditions of disks when the oldest stars formed, the observation is generally attributed to scattering processes. Both massive gas → clumps and → spiral waves are considered as scattering agents (J. A. Sellwood & J. J. Binney, 2002, astro-ph/0203510 and references therein).
Fr.: diffusion sélective
Fr.: diffusion unique, ~ simple
A type of scattering where photons are scattered only once. Single scattering dominates in → optically thin media, since photons have a high probability of exiting the medium (e.g., a thin cloud) before being scattered again.
Fr.: altération spatiale
The slight erosion of Solar System bodies (planets, moons, asteroids) caused by the → solar wind, → cosmic rays, and → micrometeorite bombardments. Space weathering affects the physical and optical properties of the surfaces of these bodies. Understanding this process is therefore important for the interpretation of remotely obtained spectral data, such as space probe photographs of outer Solar System moons.
parâkaneš bâ vâruni-ye espin
Fr.: diffusion avec renversement du spin
Quantum mechanics: The scattering of a particle that reverses the spin direction.
1) bahâr (#); 2) cešmé (#); 3) fanar (#)
Fr.: 1) printemps; 2) source; 3) ressort
1) The season that starts when the Sun, during its apparent yearly
motion, attains the celestial longitude 0 degree in the Northern
Hemisphere and 180 degrees in the Southern Hemisphere. The current
length of the spring season, around the year 2000, is about: spring
1) From the verb M.E. springen; O.E. springan "to leap, burst forth,
fly up;" the notion is of the "spring of the year," when plants "spring up" cf. Du., Ger.
1) Bahâr, from Mid.Pers. wahâr "spring;" O.Pers. vāhara-
"spring time," θūra-vāhara-
"name of a spring month;" Av. vaηhar "spring;"
cf. Skt. vasara- "relating or appearing in the morning;"
Gk. ear "spring;" L. uēr "spring," vernus "of spring;"
O.N. vār "spring;" Lith. vasara "summer;" O.C.S. vesna
Fr.: constante de rappel du ressort
A characteristic of a spring which is defined as the ratio of the force affecting the spring to the displacement caused by the force. In other words, the spring constant is the force applied if the displacement in the spring is unity. It is expressed by the equation k = -F/x (from → Hooke's law), where F = force applied, x = displacement by the spring. The spring constant is usually expressed in Newton per meter (N/m).
Fr.: grande marée
Tide that occurs when the → Earth, the → Sun, and the → Moon are in a line. This happens approximately twice a month, around → new moon and → full moon. In such a condition, known as → syzygy, the tidal force due to the Sun reinforces that due to the Moon. Spring tides have nothing to do with the season spring. The name derives from the meaning "a leap, jump, bound, rise."
Spring "a leap, jump, or bound;" M.E. springen, from spring O.E. springan "to leap, fly up; spread, grow;" cognates: O.N., O.Fris. springa, M.Du. springhen, O.H.G. springan, Ger. springen, from PIE *sprengh-, form *spergh- "to move, hasten, spring" (Skt. sprhayati "desires eagerly," Gk. sperkhesthai "to hurry."
Fr.: éjection par collision ionique
The ejection of charged particles or atoms by a solid or liquid surface which undergoes collision with high-energy ions.
Verbal noun of → sputter.
squaring the circle
cârušeš-e parhun, ~ dâyeré
Fr.: quadrature du cercle
Same as → quadrature of the circle
squaring the square
Fr.: quadrature du carré
The mathematical problem of subdividing a square into a number of smaller squares, all of different sizes.
1) General: A thin cord, usually made of twisted fibers, used for fastening,
hanging, or tying. Something that resembles string in form or texture.
M.E. string, streng; O.E. streng "line, cord, thread;" Du. streng,Ger. Strang "rope, cord;" PIE base *strenk- "stiff, tight."
Târ "thread, warp, string"
(related to tur "net, fishing net, snare,"
tâl "thread" (Borujerdi dialect),
tân "thread, warp of a web," from tanidan, tan-
"to spin, twist, weave;" Mid.Pers. tanitan; Av. tan- to stretch, extend;"
cf. Skt. tan- to stretch, extend;" tanoti "stretches,"
tántra- "warp; essence, main point;"
Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;"
Lith. tiñklas "net, fishing
net, snare," Latv. tikls "net;" PIE base *ten- "to stretch").
Fr.: théorie des cordes
The latest theory of fundamental physics in which the basic entity is a one-dimensional → brane rather than the "zero-dimensional" point of conventional elementary particle physics. The one-dimensional string-like objects exist in the normal four dimensions of → space-time plus additional dimensions, the total dimensions being ten, eleven, or twenty-six depending on the version of the theory. Particles are strings that vibrate in different ways to account for their various properties.
Fr.: source sous-marine
Hydrology: A freshwater spring that emerges off the seashore.