An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 57 Search : pin

Fr.: ralentissement   

A phenomenon in which the rotation period of a pulsar steadily decreases with the pulsar age. The cause of the spin-down is magnetic torque due to the strong fields threading out from the pulsar. The magnetic energy is being converted to high-energy particles and radiation from the nebula. Observed spin-down rates range from about 10-5 seconds/year for the youngest pulsars to about 10-12 seconds/year for recycled pulsars. The Crab pulsar is slowing down at a rate of about 10-5 seconds/year. Knowing the rotation period and the lengthening rate of a pulsar leads to its age.

spin; down, M.E.; O.E. ofdune "downward," from dune "from the hill."

Kond-carxi, from kond "slow; dull" + carxrotate + -i noun suffix.

spin-flip scattering
  پراکنش با وارونی ِ اسپین   
parâkaneš bâ vâruni-ye espin

Fr.: diffusion avec renversement du spin   

Quantum mechanics: The scattering of a particle that reverses the spin direction.

spin; flip, from flip-flap; → scattering.

Parâkaneš, → scattering; "with;" vâruni, noun from vârun, → inverse; espin, → spin.

spin-orbit coupling
  جفسری ِ اسپین-مدار، جفتش ِ ~   
jafsari-ye espin-madâr, jofteš-e ~

Fr.: couplage spin-orbite   

1) Astro.: A relationship between the orbital period of one body around another and its rotational period on its axis. The relationship results from tidal forces between the two bodies. For example, the rotation period of the Moon equals its revolution period around the Earth.
2) Quantum mechanics: The interaction between a particle's → spin angular momentum and its → orbital angular momentum.

spin; → orbit; → coupling.

duk (#)

Fr.: fuseau   

1) A rounded rod, usually of wood, tapering toward each end, used in hand-spinning to twist into thread the fibers drawn from the mass on the distaff, and on which the thread is wound as it is spun (
2) → Spindle Galaxy.

M.E. spindel, O.E. spin(e)l, from spinnan, → spin.

Duk "spindle," variants dêk, dik, ultimately from Proto-Ir. *dau- "to run;" cf. Pers. dow-, davidan "to run" (Cheung 2007).

Spindle Galaxy
  کهکشان ِ دوک   
kahkešân-e duk

Fr.: galaxie du Fuseau   

Same as → NGC 5866.

spindle; → galaxy.

xâr (#)

Fr.: épine   

1) In 3D → magnetic reconnection models of solar plasma, a field line crossing the → fan at the → magnetic null point. See also → fan (Lau & Finn. 1990, ApJ 350, 672; Parnell et al. 1996, Physics of Plasmas 3, 759).
2) A very narrow line of light extending back from the coma into the tail of some → comets.

M.E., from O.Fr. espine, from L. spina "backbone," originally "thorn, prickle," cf. L. spica "ear of corn," O.N. spikr "nail;" from PIE *spei- "sharp point."

Xâr "spine, thorn," related to xal-, xalidan "to prick, to pierce," xâridan "to scratch, itch;" Av. xvara- "wound, sore."

  لال، لعل   
lâl, la'l (#)

Fr.: spinelle   

A mineral, MgAl2O4, occurring in various colors, used as a gem, the most valuable being red. The famous "Black Prince's Ruby" which forms part of the Crown Jewels of England, is, in fact, a red spinel. Spinel has often been confounded with → ruby. The most famous source of spinel is the historic region of Badakhshan (today northeastern Afghanistan and southeastern Tajikistan). The Badakhshan mines were mentioned by Persian writers as early as the 10th century. According to a Persian tradition, these mines were first disclosed when the mountain was broken open by an earthquake.

From Fr. spinelle, from It. spinella of unknown origin.  

Lâl, la'l "spinel; red," originally "red" (cf. Tabari âl "red"); cf. Av. raoidita- "red, reddish;" Skt. rudhirá- "red, bloody;" L. ruber "red;" Gk. erythros "red;" akin to E. → red.

spinning top
  فرموک، فرفره   
farmuk (#), ferferé (#)

Fr.: toupie   

A toy that with a quick or vigorous twist spins around its symmetry axis and balances on a point. Suppose a top is perfectly fashioned so that its → rotation axis passes through its → center of mass. If it is spun carefully such that it remains perfectly upright while rotating, it will spin at a steady → angular velocity almost indefinitely in the absence of → friction. Rotation creates an → angular momentum which is directed upward along the rotation axis, opposite to the → gravity vector. However, a slight mismatch between the rotation axis and the center of mass causes gravity to exert a → torque on the top due to its weight, acting through the center of mass. The torque gives rise to a time rate of change of angular momentum, so the top experiences → precession about its point of contact. The tip of the angular momentum vector can be perceived as precessing about the → vertical, thus describing the → precessional circle. The top's precession period is given by: Tp = (4π2I)/(mgrTs), where I is the → moment of inertia, m the mass of the top, g gravity, r the distance between the center of mass and the contact point, and Ts is the spinning period of the top. Precession is accompanied by another oscillatory phenomenon, called → nutation. Nutation is less influenced by the gravity torque and is determined by the inertia forces acting on the spinning body.

spin; → -ing; top M.E., from O.E. top, maybe related to Fr. toupie.

Farmuk, ferferé "spinning top" (Dehxodâ), two words of unknown etymology.


Fr.: spinstar   

A hypothetical, very rapidly → rotating star formed in the → metal-deficient conditions of the primordial → interstellar medium. The → first stars were probably spinstars, because the lack of metals leads to faster rotation velocities. Indeed → metal-poor stars are more compact than → metal-rich ones. Stars formed from a gas whose → metallicity is below 1/2000 of the → solar metallicity could attain rotation velocities of 500-800 km s-1 (see also → Population III star). Rotation triggers → mixing processes inside the star, leading to the production of important quantities of 14N, 13C, and 22Ne (Maeder & Meynet 2012, and references therein). The production of primary 22Ne has an important impact on the → s-process  → nucleosynthesis in spinstars compared to non-rotating stars. This increases by orders of magnitude the s-process → yields of → heavy elements. Spinstars would therefore have strongly influenced the properties and appearance of the first galaxies that formed in the → Universe (See G. Meynet et al. 2009, arXiv:0709.2275; C. Chiappini, 2013, Astron. Nachr. /AN 334, No. 6, 595 and references therein).

spin; → star.


Fr.: spintronique   

A new area of science and technology which exploits the intrinsic → spin of electrons and its associated → magnetic moment, in addition to its fundamental electronic charge, in solid-state devices. In brief, spin-based electronics. For example, information could be transported or stored through the spin-up or spin-down states of electrons. Spintronics techniques are capable of much higher speed while requiring less power than the conventional method of using electron charges to represent data. The first use of spintronics was in the late 1980s with the development of → giant magnetoresistance (GMR) read heads for disk drives

Short for → spin + → electronics.

stopping power
  توان ِ بازداشت   
tavân-e bâzdâšt

Fr.: pouvoir d'arrêt   

A quantity indicating the extent with which a substance absorbs a → charged particle passing through it. It is the energy lost by a → non-relativistic particle per unit length of its path in the substance.

stop; → power.

surjective mapping
  همتایش ِ برشانی   
hamtâyeš-e baršâni

Fr.: application surjective   

Same as → surjection.

surjective; → mapping.

thermal hopping
  کپ ِ گرمایی   
kop-e garmâyi

Fr.: saut thermique   

A mechanism for the → transport of → electrons which occurs when the → Fermi level lies below a low but wide energy → barrier. The → tunneling probability across the barrier is considerably suppressed due to the width of the barrier. However, at higher temperatures, the electron can raise its energy with the assistance of a vibrational mode. The electron is said to hop from one side of the barrier to the other side via an intermediate state.

thermal; → hop; → -ing.

tidal stripping
  لُختانش ِ کشندی   
loxtâneš-e kešandi

Fr.: balayage par effet de marées   

The phenomenon whereby gas and stars are ripped out from a gravitationally → bound system, such as a galaxy or → globular cluster, by the action of → tidal forces from an external, more massive object. See also → ram pressure stripping.

tidal; → strip.


Fr.: amortissement faible   

The behavior of a damped system when the amount of damping is weak so that the system oscillates with the amplitude gradually decreasing to zero. → overdamping.

under-; → damping.


Fr.: gauchissement   

1) Geology: The slight flexing or bending of the Earth's → crust on a broad or regional scale, either upward or downward.
2) Of a galaxy, → warped disk, → warp.

Verbal noun from → warp (v.).

wind clumping
  گوده‌داری ِ باد   
gudedâri-ye bâd

Fr.: grumelage de vent   

The inhomogeneous property of a → radiation-driven wind, or the physical mechanism accounting for the → clumped wind.

clumpy; → wind.

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