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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

<< < D l dar dat de deb dec dec dec def deg del Den dep des det dev dia dif dif dil dip Dir dis dis dis dis div dom dou dow dri dus dwa dyn > >>

Number of Results: 678
discrete data
  داده‌های ِ گسسته   
dâdehâ-ye gosasté (#)

Fr.: données discrètes   

Data that can only take a small set of particular values, usually whole numbers. For instance, number of children in a family cannot be 2.4, since parents cannot actually have 2.4 children. → continuous data.

discrete; → data.

discrete radio source
  خن ِ رادیویی ِ جدا   
xan-e râdioyi-ye jodâ

Fr.: radiosource discrète   

A localized source on the celestial sphere that can be observationally separated at radio wavelengths from its background emission.

discrete; → radio; → source.

discrete spectrum
  بیناب ِ گسسته   
binâb-e gosasté

Fr.: spectre discret   

A spectrum in which the component wavelengths (and wave numbers and frequencies) constitute a discrete sequence of values (finite or infinite in number) rather than a continuum of values.

discrete; → spectrum.

discrete transition
  گذرش ِ گسسته   
gozareš-e gosasté

Fr.: transition discrète   

A transition between two quantum-mechanical energy levels. See also → discrete spectrum.

discrete; → transition.

discrete value
  ارزش ِ گسسته   
arzeš-e gosasté

Fr.: valeur discrète   

A quantity that has certain magnitudes and does not represent a → continuous variable.

discrete; → value.

discrete variable
  ورتنده‌ی ِ گسسته   
vartande-ye gosasté

Fr.: variable discret   

A variable which has only → discrete values and has no in-between values.

discrete; → variable.

discrete-time quantum walk
  پویش ِ کو‌آنتومی با زمان ِ گسسته   
puyeš-e kuântomi bâ zamân-e gosasté

Fr.: marche quantique à temps discret   

A → quantum walk involving a probabilistic → operator that changes the direction while leaving the position fixed, and a shift operator that changes the position. Discrete-time quantum walk was introduced by J. Watrous (2001, Journal of Computer and System Sciences 62, 376)

discrete; → time; → quantum; → walk.

discuss
  بهسیدن، بهس (بحث) کردن   
bahsidan, bahs kardan

Fr.: discuter   

To → consider or → examine by → argument, → comment, etc.; talk over or write about, especially to explore solutions; → debate (Dictionary.com).

M.E., from Anglo-Fr. discusser, from L. discussus "struck asunder, shaken, scattered," p.p. of discutere to break up, "strike asunder," from → dis- "apart," + quatere "to shake, strike."

Bahsidan, infinitive from bahs, from Ar. baHS (بحث) "investigating, examining, controversy, debate, dispute."

discussion
  بهس، بحث   
bahs

Fr.: discussion   

An act or instance of discussing; → consideration or → examination by → argument, → comment, etc., especially to explore solutions; informal debate (Dictionary.com).

Verbal noun from → discuss.

dish
  جام   
jâm (#)

Fr.: antenne parabolique   

A large parabolic structure that collects radio waves and focuses them on a detector by means of a secondary reflector. A similar device used as antenna for radar transmitting.

O.E. disc "plate, bowl, platter," from L. discus "dish, platter, quoit," from Gk. diskos "disk, platter."

Jâm "cup, chalice, goblet, bowl," Mid.Pers. jâm "vessel, goblet; glass," Av. yama- "glass, glass vessel," yāmô.pacika- "baked glass;" related to Skt. camasa- "a vessel used at sacrifices for drinking Soma, kind of flat dish or cup?"

disintegration
  واپاشی، فروپاشی   
vâpâši, forupâši (#)

Fr.: desintégration   

The breaking up of a body into fragments. For example, that of an unstable nuclei either spontaneously or as a result of bombardment by fast-moving particles, or the breaking up of a comet.

Disintegration, verbal noun of disintegrate, from → dis- + → integration.

Vâpâši, forupâši, from vâ-, frou-de- + pâši, noun of pâšidandisperse.

disjunct
  واجوهه   
vâjuhé

Fr.:   

Any of the components in a logical → disjunction.

disjunction.

disjunction
  واجوهش   
vâjuheš

Fr.: disjonction   

A → proposition of the form "A or B" (A ∨ B), where A and B are themselves propositions. A disjunction is → true when one or the other of its components (called → disjuncts) is true, and false otherwise.

dis-; → junction.

disk
  گرده، دیسک   
gerdé (#), disk

Fr.: disque   

1) General: Any thin, flat, circular plate or object.
2) Math.: The domain bounded by a circle.
3) Astro.: A thin, flattened material structure encompassing a central object, such as a star or a galactic nuclear region. → accretion disk; → circumnuclear disk; → circumstellar disk; → galactic disk.

Computers: Any of several types of material support on which data can be encoded.

From L. discus "quoit, discus, disk," from Gk. diskos, from dikein "to throw." → dish.

Gerdé, from Mid.Pers. girdag "disk, round," from gird/girt "round, all around," Proto-Iranian *gart- "to twist, to wreathe," cf. Skt krt "to twist threads, spin; to wind; to surround;" kata- "a twist of straw," Pali kata- "ring, bracelet," Gk. kartalos "a kind of basket," kyrtos "curved;" disk loanword from Fr.

disk accretion
  فربال ِ گرده‌ای، ~ پت گرده، ~ ~ دیسک   
farbâl-e gerde-yi, ~ pat geredé, ~ ~ disk

Fr.: accrétion par disque   

An accretion process involving an → accretion disk.

disk; → accretion.

disk galaxy
  کهکشان ِ گرده‌دار   
kahkešân-e gerdedâr

Fr.: galaxie à disque   

A galaxy consisting of a thin disk of stars and → interstellar matter which may include → spiral arms and → bar.

disk; → galaxy.

disk instability
  ناپایداری ِ گرده، ~ دیسک   
nâpâydâri-ye gerdé, ~ disk

Fr.: instabilité de disque   

1) General: The process by which an → accretion disk cools, causing it to fragment into self-gravitating → clumps.
2) A model of → planet formation in which a region of a → circumstellar disk becomes dense and cool enough to be unstable to → gravitational collapse, resulting in the formation of a gaseous → protoplanet. Disk instability has been put forward as a mechanism for forming massive → giant planets on short time-scales (1 Ky-1 My).
3) In models of galactic structure, a process that is thought to cause the formation of → pseudo-bulges.
4) → disk instability model (DIM).

disk; → instability.

disk instability model (DIM)
  مدل ِ ناپایداری ِ گرده، ~ ~ دیسک   
model-e nâpâydâri-ye gerdé, ~ ~ disk

Fr.: modèle d'instabilité de disque   

A model describing → dwarf novae and → Soft X-ray Transient (SXT)s. Accordingly, these objects are triggered by an → accretion disk instability due to an abrupt change in opacities (→ opacity) at → temperatures at which hydrogen is partially ionized. All versions of the DIM have this ingredient. They differ in assumptions about → viscosity, and about what happens at the inner and outer disk radii. Basically, during → quiescence, material accumulates in the accretion disk until a critical point is reached. The disk then becomes unstable and is dumped onto the → compact object, releasing a burst of → X-rays. However, the greater duration of SXT bursts (months) and the time interval between bursts (decades) cannot be accounted for by the standard disk instability model used for dwarf novae, and additional factors such as X-ray illumination and irradiation of the accretion disk are required for the model to match the observed properties of SXTs (J-P Lasota and J-M Hameury, 1995).

disk; → instability; → model.

disk locking
  گیرکرد ِ دیسک، ~ گرده   
girkard-e disk, ~ gerdé

Fr.: blocage de disque   

In star formation models involving magnetized accretion, a process whereby the stellar rotational → angular velocity becomes equal to the → Keplerian angular velocity of the → accretion disk. This happens at the → corotation radius. Disk locking is believed to be responsible for efficient loss of stellar → angular momentum during the → pre-main sequence contraction of → T Tauri stars. These stars are expected to spin up by a factor of about 3 due to contraction after being magnetically disconnected from the → circumstellar disk. However, observations show that a large fraction of pre-main sequence stars evolve at nearly constant angular velocity through the first 4 Myr. This process results from → magnetic braking. The idea of magnetic disk locking originated with the theory developed by Ghosh & Lamb (1979, ApJ 232, 259) for → neutron stars.

M.E., from O.E. lucan "to lock, to close," from loc "bolt, fastening, enclosure;" cf. M.L.G. lok, O.H.G. loh, O.N. lok "a cover, lid," Goth. -luk in usluk "opening," Ger. Loch "opening, hole," Du. luck "shutter."

Girkard, from gir "hold, block," from gereftan "to seize, hold, take," → eclipse, + kard noun from kardan "to do," → work.

disk population
  پرینش ِ گرده، ~ ِ دیسک   
porineš-e gerdé, ~ disk

Fr.: population disque   

Of a spiral galaxy, those stars that lie in a flattened disk and move in nearly circular orbits around its centre. They are Population I stars of all ages up to the age of the disk, but in general are younger than stars in → halo population.

disk; population, from L.L. populationem "a people, multitude," from populatio, from populare "to inhabit," from populus "people," related to plebes "the common people," cf. Gk. plethos "people, multitude, great number," from PIE base *pel- "to be full;" Mod.Pers. por "full," O.Pers. paru- "much, many," Av. pouru- "much, many," pərəna- "full," par- "to fill," Skt. puru-, Gk. polus, O.E. full "completely, full," from P.Gmc. *fullaz, O.H.G. fol, Ger. voll, Goth. full.

Like Gk., Pers. uses the concepts of "multitude, many, full" to denote "people, group, herd, flock". The following examples are all terms derived from O.Pers. paru- "much, many," Av. par- "to fill," pouru- "much, many," pərəna- "full" (Mod.Pers. por "full"): literary Pers. bâré "herd, flock," parré "a rank or file of soldiers, a circular disposition of troops," Lori, Qâyeni bor "group, tribe, herd," Torbat-Heydariyeyi, Qomi borr "heap, bundle, group," Qomi borreh "group, assemblage of people," Pashtu parrak "flock, herd," Urdu para "flock, herd," Lârestâni baila "group, tribe," Tabari balik "herd, flock." With this introduction, porineš "population," verbal noun of porinidan "to populate," infinitive of porin "populous," from por "mutitude, many, full" + -in attribution suffix.

<< < D l dar dat de deb dec dec dec def deg del Den dep des det dev dia dif dif dil dip Dir dis dis dis dis div dom dou dow dri dus dwa dyn > >>