An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1290
single scattering
  پراکنش ِ تک   
parâkaneš-e tak

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.

single; → scattering.

single-dish observation
  نپاهش ِ تک-جام   
nepâhešè-e tak-jâm

Fr.: observation avec antenne uinique   

A radio astronomical observation which uses only one antenna, in contrast to interferometric observations.

single; → dish; → observation.

single-lined binary
  دُرین ِ تک-خطه   
dorin-e tak-xatté

Fr.: binaire à une seule raie   

A → spectroscopic binary in which only one set of → spectral lines is detectable. The binary nature of the system is deduced from the fact that the spectral lines exhibit periodic → Doppler shifts due to orbital motions in the system. Same as → SB1 binary. See also: → double-lined binary.

single; → line; → binary.

singlet
  تکتایه   
taktâyé

Fr.: singulet   

A single unit; an unpaired or separate item. → doublet; → octet; → quadruplet.

From → single + -et diminutive suffix, M.E. from O.F. -et (masc.), -ette (fem.).

Taktâyé, literally "single-folded," from tak, → single, + -tâyé, from tâ- "fold, plait, ply; piece, part;" Mid.Pers. tâg "piece, part" + -yé nuance suffix.

singlet state
  حالت ِ تکتایه   
hâlat-e taktâyé

Fr.: état singulet   

In atomic physics, the electronic state of an atom or molecule for which the total → spin angular momentum is zero.

singlet; → state.

singly ionized atom
  اتم ِ یکبار یونیده   
atom-e yekbâr yonidé

Fr.: atome une fois ionisé   

An atom that has lost one electron and has become a positive ion.

single; → ionized; → atom.

singly ionized carbon
  کربون ِ یکبار یونیده   

Fr.: carbone une fois ionié   

A carbon atom → singly ionized by a photon of energy 11.3 eV. The ion C+ emits a → fine-structure line (2P3/22P1/2) at 157.7 μm when excitation conditions are satisfied (critical density ~ 3 x 103 cm-3). In → photodissociation regions, [C II] 157.7 μm is a major cooling line for regions exposed to significant → far ultraviolet (FUV) photon fluxes. In Galactic → H II regions, as well as in the central regions of external galaxies, the luminosity of the [C II] line is typically ~ 0.05-0.5% of the FUV luminosity and correlates well with → carbon monoxide (CO) line intensities.

single; → ionized; → carbon.

singular
  تکین   
takin (#)

Fr.: singulier   

Math.: 1) Of or pertaining to a linear transformation from a vector space to itself that is not one-to-one.
2) Of or pertaining to a matrix having a determinant equal to zero.

M.E., from O.Fr. singuler "single, separate," from L. singularis "single, solitary," from singulus "one, individual, separate," from sim- (stem of simplus) + diminutive suffix.

Takin, from tak "single, alone," related to tâq "odd, single," tâ, tâh "piece, part; fold, plait, ply;" Mid.Pers. tak "single," tâg, tâk, tâi "unit, piece, after numerals" + -in adj. suffix.

singular isothermal sphere
  کره‌ی ِ ایزودمای ِ تکین   
kore-ye izodamâ-ye takin

Fr.: sphère isotherme singulère   

In models of star formation, an isothermal sphere in which the density distribution in the static or nearly static outer envelope obeys an r-2 power law. In the limit of infinite central concentration, the unstable equilibrium approaches the singular isothermal sphere which has the density and mass distributions ρ(r) = (a2/2πG)r-2 and M(r) = (2a2/G)r, where a is the isothermal → sound speed inside the cloud, G is the → gravitational constant, and r the distance from the center (F. H. Shu, 1977, ApJ 214, 488).

singular; → isothermal; → sphere.

singular matrix
  ماتریس ِ تکین   
mâtris-e takin

Fr.: matrice singulière   

A → square matrix that does not have a → matrix inverse.

singular; → matrix.

singular point
  نقطه‌ی ِ تکین   
noqte-ye takin

Fr.: point singulier   

The point M0(x0,y0) of the curve F(x,y) = 0, where at least one of the → partial derivatives ∂F/∂x and ∂F/∂y vanishes. See also → ordinary point.

singular; → point.

singular solution
  لویش ِ تکین   
luyeš-e takin

Fr.: solution singulière, ~ particulière   

Of partial differential equations, the solution which cannot be obtained from the general solution by particular choice of arbitrary functions. → general solution; → particular solution.

singular; → solution.

singularity
  تکینی   
takini (#)

Fr.: singularité   

1) Math.: A point at which a given mathematical object is not defined.
2) Physics: A point in → space-time in which gravitational force causes space-time to have infinite curvature; matter is crushed to infinite density and zero volume. This happens at the center of a → black hole where space and time cease to exist as we know them, and the known laws of physics break down. See also → Schwarzschild singularity; → initial singularity.

singular + → -ity.

sink
  چاهک   
câhak (#)

Fr.: puits   

1) A region within a system where mass or energy is given up, in contrast to a → source, where mass or energy is released.
2) In hydrodynamics simulation codes of gaseous collapse and → accretion, such as → smoothed particle hydrodynamics (SPH), a region of the flow that accretes incoming material but that does not allow it to leave. In in theses simulations an enormous dynamic range is usually encountered, which makes the full problem computationally infeasible. Indeed dynamic range requires enough resolution elements in both space and time to resolve the largest and smallest scales present in the problem. Sinks provide a way of concentrating resolution in regions of interest and evolving different regions with different time-steps. These entities can have stellar scale masses. See also → sink particle.

M.E. sinken, O.E. sincan, from verb; cf. O.S. sinkan, O.N. sökkva, M.Du. sinken, Du. zinken, O.H.G. sinkan, Ger. sinken, Goth. sigqan "to sink."

Câhak, from câh "a well" (Mid.Pers. câh "a well;" Av. cāt- "a well," from kan- "to dig," uskən- "to dig out;" O.Pers. kan- "to dig;" Mod.Pers. kandan "to dig;" cf. Skt. khan- "to dig," khanati "he digs," kha- "cavity, hollow, cave, aperture") + -ak diminutive suffix.

sink particle
  ذره‌ی ِ چاهک   
zarre-ye câhak

Fr.: particule puits   

In hydrodynamics codes, a way of treating a collapsing or accreting region, such as a star, as a simple → point mass. Indeed, in many situations, the scale of interest is much larger than the scale of the → accreting object itself and it would be impossible to perform the calculation otherwise. → Sinks are generally modeled as → Lagrangian particles (see, e.g., Bates et al. 1995, MNRAS 277, 362; Krumholz et al. 2004, ApJ 611, 399; Federrath et al. 2010, ApJ 713, 269).

sink; → particle.

Sinope
  سینوپه   
Sinopé (#)

Fr.: Sinopé   

The outermost of Jupiter's known confirmed satellites, also known as Jupiter IX, discovered by Seth B. Nicholson (1891-1963) in 1914. With a visual magnitude of 18.3, it has a diameter of 28 km and orbits Jupiter at a mean distance of 23,848,000 km every 753 days.

In Gk. mythology a Naias Nymphe who was abducted by Zeus to a Black Sea coast where the city of Sinope was named for her. According to most sources, she tricked Zeus into swearing an oath promising her her virginity.

sinusoidal
  سینوسی   
sinusi (#)

Fr.: sinusoïdal   

Having the characteristics of a sine function; same as → sine wave.

From sinus, → sine, + → -al.

sip
  ۱)چشلیدن؛ ۲) چشل   
1) cašelidan; 2) cašel

Fr.: 1) siroter, boire à petite gorgées; 2) gorgée   

1) To drink (a liquid) a little at a time; take small tastes of.
2) An instance of sipping; a small taste of a liquid; a small quantity taken by sipping (Dictionary.com).

M.E. sippen (v.), akin to Low German sippen "to sip."

Cašel, from Pashto cašəl "to drink," caceq "to drip;" related to cašidan "to taste," → taste.

siphon
  سیفون   
sifon (#)

Fr.: siphon   

A ∩-shaped tube with unequal arms that is used to move a liquid from one level to a lower level via a third level higher than either. Once the short arm is filled, for example, by suction, the liquid flows down in the long arm under the action of gravity due to mass excess in it.

From Fr. siphon, from L. sipho (genitive siphonis), from Gk. siphon "pipe, tube," of unknown origin.

Sirius (α CMa)
  تیشتر   
Tištar (#)

Fr.: Sirius   

The white star that is the brightest in the constellation → Canis Major and the brightest star of the sky (V = -1.46). Its particular brightness is mostly due to its proximity to the Earth, being a mere 8.6 → light-years away, the fifth closest star system. Sirius is a → dwarf of → spectral type A1 V with an → effective temperature of 9880 K, and a luminosity 26 times more so than the Sun. It has a radius of 1.75 solar and a minimum equatorial rotation speed of 16 km/sec, and rotates in less than 5.5 days. Sirius is a visual binary (separation 4.6 arcsec, period 50 years), the companion Sirius B being the first white dwarf to be discovered. Sirius is "metal rich," its iron content triple that of the Sun, most likely from some sort of elemental diffusion.

From L. Sirius, from Gk. Seirios, literally "scorching," because of its brightness.

Tištar, from Mid.Pers. Tištar, from Av. Tištrya- "(name of the deified star) Sirius," literally "the one who belongs to the three stars," in reference to the three stars of → Orion's Belt; ultimately from PIE *tri-str-o-m- "group of three stars," then *tri-str-iia- and by dissimulation Indo-Iranian *ti-str-iia-, Av. *Tištriia- and Vedic Skt. Tisyà (A. Panaino, in Iranica, under Tištrya).

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