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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1298
slingshot effect
  اُسکر ِ فلاخن   
oskar-e falâxan

Fr.: effet de fronde gravitationnelle, gravidéviation   

An important astronautical technique whereby a spacecraft takes up a tiny fraction of the gravitational energy of a planet it is flying by, allowing it to change trajectory and speed. Also known as → gravitational slingshot or → gravitational assist.

Slingshot, from sling, from M.E. slyngen, from O.N. slyngva "to sling, fling" + shot, from M.E., from O.E. sc(e)ot, (ge)sceot; cf. Ger. Schoss, Geschoss; → effect.

Oskar, → effect; falâxan "sling;" from Av. fradaxšana- "sling," fradaxšanya- "sling, sling-stone;"

slit
  شکاف   
šekâf (#)

Fr.: fente   

A long, thin opening in a spectrograph allowing only the light studied to fall on the prism.

O.E. slitan "to cut or tear up, slit;" cf. O.S. slitan, O.N. slita, M.L.G., M.Du. sliten, Du. slijten, O.H.G. slizan, Ger. schleißen "to slit."

Šekâf "slit," from Mod./Mid.Pers. škâf- škâftan "to split, burst;" Proto-Iranian *kap-, *kaf- "to split;" cf. Gk. skaptein "to dig;" L. cabere "to scratch, scrape," P.Gmc. *skabanan (Goth. skaban; Ger. schaben; E. shave). PIE base *(s)kep- "to cut, to scrape, to hack."

slit spectrograph
  بیناب‌نگار ِ شکاف‌مند   
binâbnegâr-e šekâfmand

Fr.: spectrographe à fente   

A type of spectrograph that uses a slit to provide resolution.

slit; → spectrograp.

slitwidth
  شکاف-پهنا   
šekâf-pahnâ

Fr.: largeur de fente   

The width size of the slit which determines the spectral resolution of a spectrograph.

slit; → width.

slope
  شیب   
šib (#)

Fr.: pente   

1) An inclined surface; deviation from the horizontal or vertical.
2) The tangent of the angle formed by the intersection of a given straight line and the X-axis of a system of Cartesian coordinates.
3) The derivative of the function whose graph is a given curve evaluated at a designated point.
4) The exponent of the → initial mass function . See also → Salpeter slope.
5) → slope parameter.

From M.E. aslope (adv.) "on the incline," from O.E. *aslopen, p.p. of aslupan "to slip away," from a- "away" + slupan "to slip."

Šib "slope, descent, declivity," contraction of nešib, našib "declivity, descent; lowness of ground, slope of any place;" Mid.Pers. nišēp "declivity, (astrology) dejection," Av. *nixšvaēpā-, xšvaēpā- "bottom, rear."

slope parameter
  پارامون ِ شیب   
pârâmun-e šib

Fr.: paramètre de pente   

In a → power-law distribution or → regression, the → exponent that represents the effect of the → independent variable, x, on the → dependent variable, y. X has no association with y if the slope parameter = 0 and x has strong association with y if the slope parameter is large.

slope; → parameter.

slow
  آهسته   
âhesté (#)

Fr.: lent   

Moving or proceeding with little or less than usual speed or velocity.

O.E. slaw "inactive, sluggish;" cf. O.S. sleu "blunt, dull," M.Du. slee, Du. sleeuw "sour, blunt," O.H.G. sleo "blunt, dull," O.N. sljor, Dan. sløv, Swed. slö "blunt, dull."

Âhesté "slow, quiet, tender, soft," ultimately from Proto-Iranian *ā-hasta-ka-, literally "at rest, motionless, seated." The first and third components are affixes, the main component from *had- "to "sit, be seated;" cf. Av. had- "to sit" (nī...hazdiiāt "would sit down"); Pers. nešastan "to sit;" PIE base *sed- "to sit;" cf. Skt. sad- to sit," sidati "sits;" Gk. hezomai "to sit," hedra "seat, chair;" L. sedere "to sit;" O.Ir. suide "seat, sitting;" Welsh sedd "seat;" Lith. sedmi "to sit;" Rus. sad "garden;" Goth. sitan, Ger. sitzen; E. sit.

slow neutron
  نوترون ِ آهسته   
notron-e âhesté (#)

Fr.: neutron lent   

A neutron whose kinetic energy does not exceed about 10 electron-volts. Also called → thermal neutron.

slow; → neutron.

slow nova
  نو-اختر ِ آهسته   
now-axtar-e âhesté

Fr.: nova lente   

A type of nova whose light curve exhibits a characteristically slow development, having a rise time of several days, maximum of several weeks, and slower decline.

slow; → nova.

Slowly Pulsating B star (SPB)
  ستاره‌ی ِ آهسته تپنده‌ی ِ گونه‌ی ِ B   
setâre-ye âhesté tapande-ye gune-ye B

Fr.: étoile B pulsante à longue période   

A member of a class of → B stars that are situated along the → main sequence with → spectral types ranging from B2 to B9 and masses from 3 to 7 → solar masses. In the → H-R diagram the SPB group lies below → beta Cephei variables, which are more massive. SPBs show light and line-profile variations that are multi-periodic with periods of the order of days. This variability is understood in terms of non-radial → stellar pulsations, and their → oscillation modes are high-order → g modes. Theoretical models attribute the pulsational nature of SPBs to the → kappa mechanism, acting in the metal → opacity bump at 2 x 105 K. Their g-mode pulsations penetrate deep into the stellar interior, making these objects very promising for → asteroseismology. Several oscillation modes are excited simultaneously, resulting in periodicities on time scales of the order of months or even years. The prototype of this group is 53 Per. First introduced as a distinct class by Waelkens (1991, A&A 246, 453).

slow; → pulsating; → B star.

slug
  لیسک   
lisak (#)

Fr.: limace   

A worm-like gastropod that is related to the → snail family but has no shell.

M.E. slugge "sluggish," probably from Scandinavian; cf. dialectal Norwegian sluggje "heavy, slow person."

Lisak dialectal Tabari (also see Dehxodâ)

small
  کوچک، کم   
kucak (#), kam (#)

Fr.: petit   

Of limited size; of comparatively restricted dimensions; not large. → method of small perturbations; → Small Magellanic Cloud (SMC).

M.E. smale; O.E. smæl "slender, narrow, small;" cf. Dan., Swed., M.Du., Du., O.H.G. smal, O.Fris. smel, Ger. schmal "narrow," Goth. smalista "smallest."

Kucak "small;" Mid.Pers. kucak "small," related to kutâh "short, small, little," kudak "child, infant," kutulé, → dwarf; Mid.Pers. kôtâh "low," kôtak "small, young; baby;" Av. kutaka- "little, small."
Kam "little, few; deficient, wanting; scarce," from Mid.Pers. kam "little, small, few," O.Pers./Av. kamna- "small, few."

Small Dipper
  هفت خواهران، چمچه‌ی ِ کوچک   
haft xâharân, camce-ye kucak

Fr.: Petite Ourse   

Same as → Little Dipper.

small; → Little Dipper.

Small Magellanic Cloud (SMC)
  ابر ِ کوچک ِ ماژلان   
Abr-e Kucak-e Magellan (#)

Fr.: Petit Nuage de Magellan   

An irregular galaxy, the smaller of the two Magellanic Clouds that are satellites of our own Galaxy, lying in the southern constellation → Tucana. The SMC is about 10,000 light-years in diameter and some 200,000 light-years away. It has a visible mass of about 1/50-th that of our Galaxy and 1/10-th of that of the LMC. Its heavy element content is about a factor 5 smaller than that of the Galaxy. The SMC is the third-nearest external galaxy after the → Sagittarius Dwarf Elliptical Galaxy and the → Large Magellanic Cloud (LMC).

small; Magellanic named in honor of Ferdinand Magellan, the Portuguese navigator (c 1480-1521), who undertook the first voyage around the world. The two Clouds were first described by Magellan's chronicler Pigafetta, after leaving the Strait of Magellan in 1520; → cloud.

small solar system body
  جسم ِ کوچک ِ راژمان ِ خورشیدی   
jesm-e kucak-e râžmân-e xoršidi

Fr.: petit corps du système solaire   

A term introduced by the → International Astronomical Union (August 2006) to name the → solar system bodies other than → planets and → dwarf planets. Small solar system bodies include → asteroids, → comets, and → meteoroids.

small; → solar; → system; → body.

Smith's cloud
  ابر ِ اسمیت   
abr-e Smith

Fr.: nuage de Smith   

A huge, → high-velocity cloud of hydrogen gas that measures some 9,800 × 3,300 → light-years. It is located between 36,000 and 45,000 light-years away from Earth in the northern constellation of → Aquila. It has a mass of at least 106 → solar masses. It is now moving toward the disk of the → Milky Way at 73 ± 26 km/s and is expected to hit the disk of our Galaxy in about 27 million years, at an angle of approximately 45° at a point in the → Perseus Arm, one of two major → spiral arms of the Galaxy.

Named after Gail Bieger, née Smith, who discovered the cloud in 1963, when she was an astronomy student at Leiden University in the Netherlands; → cloud.

smog
  دودمه   
dudmeh (#)

Fr.: smog   

A fog combined with smoke or other forms of atmospheric pollutants in an unhealthy or irritating mixture.

From sm(oke) + (f)og; → smoke; → fog.

Dudmeh, from dud, → smoke, + meh, → fog.

smoke
  دود   
dud (#)

Fr.: fumée   

A mass of tiny particles in the air that rises up from something burning.

M.E., O.E. smoca, related to smeocan "give off smoke;" cf. M.Du. smooc, Du. smook, M.H.G. smouch, Ger. Schmauch; PIE base *smeug(h)- "smoke" (cf. Arm. mux "smoke," Gk. smukho "to burn in a smoldering fire," O.Ir. much, Welsh mwg "smoke").

Dud, from Mid.Pers. dût, dûd "smoke;" Av. dunman- "cloud," duuan- "to fly;" cf. Skt. dhvan- "to smoke;" Hittite tuhhae- "to prouce smoke;" PIE base *dheu- "to blow, reel; smoke, dark."

smooth
  ۱) هموار؛ ۲) هموار کردن   
1) hamvâr (#); 2) hamvâr kardan (#)

Fr.: 1) lisse; 2) lisser   

1) Of a curve, free from bumps or abrupt irregularities.
2) To modify a sequential set of numerical data by reducing the differences in magnitude between adjacent values.

O.E. smoð "free from roughness, not harsh," of unknown origin.

Hamvâr "level, equal, an even place or thing," from ham- "same, equally, even; together, with" (Mid.Pers. ham-, like L. com- and Gk. syn- with neither of which it is cognate. O.Pers./Av. ham-, Skt. sam-; also O.Pers./Av. hama- "one and the same," Skt. sama-, Gk. homos-; originally identical with PIE numeral *sam- "one," from *som-. The Av. ham- appears in various forms: han- (before gutturals, palatals, dentals) and also hem-, hen-) + -vâr similarity suffix.

smooth curve
  خم ِ هموار   
xam-e hamvâr

Fr.: courbe lisse   

1) A curve which is free from abrupt fluctuations.
2) A curve if it has tangents at all points and the angle of inclination of the tangent is a continuous function of the arc length.

smooth; → curve.

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