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: 3079 Search : on
simple population
  پرینش ِ ساده   
porineš-e sâdé

Fr.: population simple   

A set of stars resulting from a spatially (≤ few pc) and temporally (≤ Myr) correlated star formation event.

simple; → population.

simplification
  ساده‌کرد، ساده‌شد   
sâde-kard, sâde-šod

Fr.: simplification   

The act of simplifying, or the fact of being simplified.

Verbal noun of → simplify.

simulation
  مانندش، همانندسازی   
mânandeš, hamânand sâzi

Fr.: simulation   

The construction of a mathematical model to reproduce the characteristics of a phenomenon, system, or process, often using a computer, in order to infer information or solve problems.

Verbal noun of → simulate.

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.

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 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.

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.

site selection
  گزینش ِ سیت   
gozineš-e sit

Fr.: sélection de site   

The process of choosing a site for an astronomical observatory based on meteorology, seeing conditions, and access to the site.

site; → selection.

situation
  سیتش   
siteš

Fr.: situation   

1) The manner of being placed with respect to surroundings.
2) Momentary state; a set of circumstances.

Verbal noun of → situate.

sky subtraction
  زیرکرشش ِ آسمان   
zirkaršeš-e âsmân

Fr.: soustraction de ciel   

The act or instance of removing the contribution of non-related, intervening foreground light to the object.

sky; → subtraction.

slepton
  اسلپتون   
slepton

Fr.: slepton   

In → supersymmetry theories, a hypothetical → boson super-partner of a → lepton. See also → squark

s from → supersymmetry; → lepton.

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.

SMASS classification
  رده‌بندی ِ SMASS   
radebandi-ye SMASS

Fr.: classification SMASS   

An asteroid taxonomy built on the → Tholen classification but based on the presence or absence of → absorption features in the visible part of the spectrum. In many cases the two classifications are the same, but the Tholen C and S classes are subdivided in the SMASS classification.

SMASS stands for the Small Main-belt Asteroid Spectroscopic Survey, → small; → main belt; → asteroid; → spectroscopic; → survey; → classification.

Sobolev approximation
  نزدینش ِ سوبولف   
nazdineš-e Sobolev

Fr.: approximation de Sobolev   

A method allowing for a simplified solution to the → radiative transfer equation at frequencies of spectral lines in media moving with a high velocity gradient. This method assumes that the macroscopic velocity gradients are more important than local random variations of thermal line width: dv/dr > vth/l, where dv/dr is the velocity gradient, vth is the thermal broadening of the line, and l the length scale. The Sobolev approximation is only valid if the conditions of the gas do not change over the → Sobolev length. Under the Sobolev approximation, each point in the medium is isolated from other points, and the → radiative transfer problem becomes a local one and therefore much easier to solve.

Named after the Russian astronomer Viktor Viktorovich Sobolev, Moving Envelopes of Stars [in Russian], Leningr. Gos. Univ., Leningrad (1947) [translated by S. Gaposchkin, Harvard Univ. Press, Cambridge, Mass. (1960)]; → approximation.

socialization
  هزانش   
hazâneš

Fr.: socialisation   

A continuing process whereby an individual acquires a personal identity and learns the norms, values, behavior, and social skills appropriate to his or her social position (Dictionary.com).

socialize; → -tion.

Socratic irony
  گواژه‌ی ِ سقراطی، ~ سقراتی   
govâže-ye Soqrâti

Fr.: ironie socratique   

A means by which the pretended ignorance of a skillful questioner leads the person answering to expose his own ignorance (Collins).

Socratic; → irony.

Sodium Moon Spot (SMS)
  لکه‌ی ِ سودیومی ِ مانگ   
lake-ye sodiomi-ye Mâng

Fr.: tache de sodium de la Lune   

The → sodium tail of the Moon as it appears in the sky opposite the Sun. The SMS undergoes changes in shape and brightness. It is brighter when the → new moon occurs at → perigee, when the new moon is north of the → ecliptic, and approximately five hours after the new moon.

sodium; → Moon; → spot.

sodium tail of the Moon
  دنباله‌ی ِ سودیومی ِ مانگ   
donbâle-ye sodiomi-ye Mâng

Fr.: queue de sodium de la Lune   

A comet-like tail of the Moon comprised of → sodium (Na) atoms and invisible to the naked eye. The lunar surface is constantly bombarded by the → solar wind, → photons, and → meteoroids, which can liberate Na atoms from the → regolith. These atoms are subsequently accelerated by solar → radiation pressure to form a long comet-like tail opposite the Sun. Near → new moon, this diffuse cloud of Na atoms encounters the Earth's gravity and is "pinched" into a beam of enhanced density. This beam appears as the ~3° diameter Sodium Moon Spot (SMS) seen in the sky opposite the Sun. The spot is about five times the diameter of the → full moon, and is 50 times fainter than can be seen with the unaided eye. The spot is reflected light from millions of Na atoms that two days earlier were on the surface of the Moon. This spot is visible to sensitive cameras equipped with filters tuned to the orange light emitted by Na atoms near 589.3 nm (Baumgardner et al., 2021 Journal of Geophysical Research: Planets DOI: 10.1029/2020je006671).

sodium; → tail; → Moon.

soft iron
  آهن ِ نرم   
âhan-e narm

Fr.: fer doux   

Iron that has a low carbon content, in contrast to → steel. Because it is easily magnetized and demagnetized, it is used to make the cores of → solenoids and other electrical equipment.

soft; → iron.

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