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: 232 Search : ist
spectral energy distribution (SED)
  واباژش ِ کاروژ ِ بینابی   
vâbâžeš-e kâruž-e binâbi

Fr.: distribution de l'énergie spectrale   

A plot showing the energy emitted by a source as a function of the radiation wavelength or frequency. It is used in many branches of astronomy to characterize astronomical sources, in particular mainly in → near infrared and → middle infrared to study → protostars or → young stellar objects. The SED of these objects is divided in four classes.
Class 0 in which the SED represents a very embedded protostar, where the mass of the central core is small in comparison to the mass of the → accreting envelope. The SED is characterized by the → blackbody radiation of the envelope and peaks at → submillimeter wavelengths.
Class I objects possess a SED that peaks in the → far infrared and is characterized by a weak contribution of the blackbody of the central protostar (detected in near infrared) and the emission of a thick disk and dense envelope. These objects have less mass in the envelope and more massive central cores with respect to Class 0.
Class II objects are the → classical T Tauri stars with a SED due to the emission of a thin disk and the central star. They have accumulated most of their final mass and have dispersed almost completely their circumstellar envelope.
Finally, Class III objects have pure photospheric spectra. Their SED is peaked in the optical and is well approximated by a blackbody emission with a faint → infrared excess due to the presence of a residual optically thin disk that may be the origin of → planetesimals.
This classification scheme can be made more quantitative by defining a → spectral index.

spectral; → energy; → distribution.

star formation history
  تاریخ ِ دیسش ِ ستاره   
târix-e diseš-e setâré

Fr.: histoire de formation d'étoiles   

The → star formation rate as a function of time.

star; → formation; → history.

statistical
  آماری   
âmâri (#)

Fr.: statistique   

Of, pertaining to, consisting of, or based on → statistics.

Statistic, from → statistics + → -al.

statistical analysis
  آنالس ِ آماری   
ânâlas-e âmâri

Fr.: analyse statistique   

The process of collecting, manipulating, analyzing, and interpreting quantitative data to uncover underlying causes, patterns, and relationships between variables.

statistical; → analysis.

statistical equilibrium
  ترازمندی ِ آماری   
tarâzmandi-ye âmâri

Fr.: équilibre statistique   

A state in which the average density of atoms per cubic centimeter in any atomic state does not change with time and in which, statistically, energy is equally divided among all degrees of freedom if classical concepts prevail.

statistical; → equilibrium.

statistical hypothesis
  انگاره‌ی ِ آماری   
engâre-ye âmâri

Fr.: hypothèse statistique   

An assumed statement about the way a → random variable is distributed. A statistical hypothesis generally specifies the form of the → probability distribution or the values of the parameters of the distribution. The statement may be true or false. See also → null hypothesis.

statistical; → hypothesis.

statistical hypothesis testing
  آزمون ِ انگاره‌ی ِ آماری   
âzmun-e engâre-ye âmâri

Fr.: test d'hypothèse statistique   

A method of making decision between rejecting or not rejecting a → null hypothesis on the basis of a set of observations.

statistical; → hypothesis; → test.

statistical inference
  دربرد ِ آماری   
darbord-e âmâri

Fr.: inférence statistique   

The process of inferring certain facts about a → statistical population from results found in a → sample.

statistical; → inference.

statistical law
  قانون ِ آماری   
qânun-e âmâri (#)

Fr.: loi statistique   

A law that governs the behavior of a system consisting of a large number of particles and which differs from the laws obeyed by each of the particles making up the macroscopic system. See also → dynamical law.

statistical; → law.

statistical mechanics
  مکانیک ِ آماری   
mekânik-e âmâri (#)

Fr.: mécanique statistique   

statistical physics.

statistical; → mechanics.

statistical parallax
  دیدگشت ِ آماری   
didgašt-e âmâri

Fr.: parallaxe statistique   

The mean parallax of a group of stars that are all at approximately the same distance, as determined from their radial velocities and proper motions.

statistical; → parallax.

statistical physics
  فیزیک ِ آماری   
fizik-e âmâri (#)

Fr.: physique statistique   

The branch of physics that applies methods of → probability theory and → statistics to the behavior of large numbers of microscopic particles (such as molecules, atoms, or subatomic particles) in order to explain and predict the overall properties of the system composed of such particles.

statistical; → physics.

statistical population
  پرینش ِ آماری   
porineš-e âmâri

Fr.: population statistique   

Any collection of individuals or items from which → samples are drawn. See also → finite population, → infinite population.

statistical; → population.

statistical thermodynamics
  گرماتوانیک ِ آماری   
garmâtavânik-e âmâri

Fr.: thermodynamique statistique   

Same as → statistical mechanics.

statistical; → thermodynamics.

statistical weight
  وزن ِ آماری   
vazn-e âmâri

Fr.: poids statistique   

1) Statistics: A number assigned to each value or range of values of a given quantity, giving the number of times this value or range of values is found to be observed.
2) Statistical mechanics: A multiplicative factor in the expression for the probability of finding a system in a given quantum state. Usually the number of degenerate substates contained in the state.

statistical; → weight.

statistics
  آمار   
âmâr (#)

Fr.: statistique   

A branch of applied mathematics that deals with the collection and interpretation of quantitative data and the use of probability theory to estimate population parameters.

From Ger. Statistik "political science," from Mod.L. statisticus (collegium) "state affairs," from It. statista "person skilled in statecraft," from stato "state," ultimately from L. status "position, form of government;" cognate with Pers. ist-, istâdan "to stand" (Mid.Pers. êstâtan; O.Pers./Av. sta- "to stand, stand still; set;" Av. hištaiti; cf. Skt. sthâ- "to stand;" Gk. histemi "put, place, weigh," stasis "a standing still;" L. stare "to stand;" Lith. statau "place;" Goth. standan; PIE base *sta- "to stand").

Âmâr "computation, arithmetic; statistics," from âmârdan "to reckon, to calculate," related to ošmârdan, šomârdan, šomordan "to count, to calculate," mar, mâr- "count, reckon, measure," bimar "countless," nahmâr "great, large, big;" Mid.Pers. âmâr "calculating, reckoning;" Av. base mar- "to have in mind, remember, recall," hišmar-; cf. Skt. smr-, smarati "to remember, he remembers," L. memor, memoria, Gk. mermera "care," martyr "witness."

subrelativistic
  زیر-بازانیگی‌مند   
zir-bazânigimand

Fr.: subrelativiste   

Describing a system or situation for which the → Lorentz factor, γ, is much smaller than 1. See also → ultrarelativistic.

ultra- + → relativistic

syllogistic
  باهمشماریک   
bâhamšomârik (#)

Fr.: syllogistique   

1a) Of or pertaining to a → syllogism.
1b) Like or consisting of syllogisms.
2a) The part of logic that deals with syllogisms.
2b) Syllogistic reasoning (Dictionary.com).

syllogism; → -ic.

theist
  یزدان‌باور   
yazdân-bâvar (#)

Fr.: théiste   

A person who believes in → theism.

theism; → -ist

Themisto
  تمیستو   
Themisto

Fr.: Thémisto   

A small satellite of → Jupiter, ninth in order from the planet. It is about 8 km in diameter and orbits Jupiter at a mean distance of 7 500 000 km every 130 days. It was discovered in 1975, lost, and then rediscovered in 2000. Also known as Jupiter XVIII.

Named after Themisto, daughter of the river god Inachus, who became the mother of Ister (the river Danube) by Zeus (Jupiter).

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