An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 42 Search : variable
independent random variables
  ورتنده‌های ِ کاتوره‌ی ِ ناوابسته   
vatandehâ-ye kâture-ye nâvâbasté

Fr.: variables aléatoires indépendantes   

Statistics: Two random variables X and Y if and only if the value of X has no influence on the value of Y and vice versa.

dependent; → random; → variable.

independent variable
  ورتنده‌ی ِ ناوابسته   

Fr.: variable indépendante   

Math.: A variable whose value determines the value of other variables. For example, x, in the expression y = f(x), is the independent variable. See also → dependent variable.

independent; → variable.

individual variable
  ورتنده‌ی ِ تکال   
vartande-ye takâl

Fr.: variable individuel   

In → predicate logic, a variable which represents an unspecified → subject. Individual variables work just as do variables in algebra, they stand in for a value, but have no fixed value of their own. They are represented by lower case letters taken from the end of the alphabet x, y, z; and if additional variables are needed by u, v, w, as well.

individual; → variable.

intrinsic variable
  ورتنده‌ی ِ درونگین   
vartande-ye darungin

Fr.: variable intrinsèque   

A variable star whose fluctuations in brightness are due to natural changes in the luminosity of the star itself, not by external causes, such as in → extrinsic variable stars.

intrinsic; → variable.

invariable plane
  هامُن ِ ناورتنده   
hâmon-e nâvartandé

Fr.: plan invariable   

Mechanics: For a rotating rigid body not subject to external torque, a plane which is perpendicular to the angular momentum vector of the body, and which is always tangent to its → inertia ellipsoid.

Invariable negation of → variable; → plane.

irregular variable
  ورتنده‌ی ِ بی‌سامان   
vartande-ye bisâmân

Fr.: variable irrégulière   

A type of variable star in which variations in brightness show no regular periodicity. There are two main types, irregular eruptive variables and irregular pulsating variables.

irregular; → variable.

linguistic variable
  ورتنده‌ی ِ زبانیک   
vartande-ye zabânik

Fr.: variable linguistique   

One of several → input or → output variables of a → fuzzy logic system whose values are → words or → sentences from a natural language, instead of numerical values.

linguistic; → variable.

long-period variable
  ورتنده‌ی ِ درازدوره   
vartande-ye derâz dowré

Fr.: variable à longue période   

A type of → variable star in which variations in brightness occur over long time-scales of months or years. The term generally refers to → Mira variable types.

long; → period; → variable.

Luminous Blue Variable (LBV)
  ورتنده‌ی ِ آبی ِ تابان   
vartande-ye âbi-ye tâbân

Fr.: variable bleue lumineuse   

A high-luminosity variable star, which represents a transition phase in the life of a massive star when it evolves off the main sequence to become a supernova. Only about a dozen confirmed LBVs are presently known in our Galaxy. → Hubble-Sandage variable.

luminous; → blue; → variable.

Mira variable
  ورتندگان ِ میراوار   
vartandegân-e Mirâ-vâr

Fr.: variables de type Mira   

A periodic → variable star with cycles 100-500 days, and of → spectral types K, M, S, and C; also called → long-period variables.

Mira; → variable.

nebular variable
  ورتنده‌ی ِ میغی   
vartande-ye miqi

Fr.: variable nébulaire   

A type of eruptive variable star, mainly young FU Orionis and T Tauri types, associated with nebulosity.

nebular; → variable.

optically violent variable (OVV) quasar
  کو‌آسارِ ورتنده‌ی ِ نورانه سورا   
kuâsâr-e vartande-ye nurâné surâ

Fr.: quasar variable optiquement violent   

A member of a small subset of quasars consisting of bright radio galaxies whose flux of visible light output can vary by as much as 50% in a single day.

optically; → violent; → variable; → quasar.

periodically variable supergiant (PVSG)
  ابرغول ِ ورتنده‌ی ِ دوره‌ای   
abarqul-e vartande-ye dowreyi

Fr.: supergéante variable périodiquement   

A variable → supergiant star with typical periods of the order of 10 to 100 days and amplitudes less than a few tenths of a magnitude. PVSGs are thought to be pulsating → g modes, caused by a density inversion, arising from an → opacity bump, most likely from Fe, H, and/or He.

periodical; → -ly; → variable; → supergiant.

propositional variable
  ورتنده‌ی ِ گزاره‌ای   
vartande-ye gozâre-yi

Fr.: variable propositionnel   

Logic: A → propositional symbol that represents any → proposition whatsoever.

propositional; → variable.

random variable
  ورتنده‌ی ِ کاتوره   
vartande-ye kâturé

Fr.: variable aléatoire   

A quantity that takes different real values as a result of the → outcomes of a → random event or experiment involving specified probabilities.

random; → variable.

real dynamical variable
  ورتنده‌ی ِ توانیک ِ هسیا   
vartande-ye tavânik-e hasyâ

Fr.: variable dynamique réel   

A → dynamical variable which does not have an → imaginary number part.

real; → dynamical; → variable.

semiregular variable
  ورتنده‌ی ِ نیمه‌بسامان   
vartande-ye nime-besâman

Fr.: variable semirégulière   

A type of giant or supergiant pulsating variable star, with intermediate or late spectra, showing noticeable periodicity in its light changes, accompanied or sometimes interrupted by various irregularities. Periods lie in the range from 20 to more than 2000 days, while the shapes of the light curve may be rather different and variable with each cycle. The amplitudes may be from several hundredths to several magnitudes (usually 1-2 magnitudes in the V filter). Examples are Betelgeuse, Antares, and Rasalgethi. Semiregular variables are classified in several subtypes: SRA, SRB, SRC, and SRD.

semi-; → regular; → variable.

short-period variable
  ورتنده‌ی ِ کوتاه-دوره   
vartande-ye kutâh-dowré

Fr.: variable à courte période   

A variable star that has a relatively short period with respect to stars of similar types.

short; → period; → variable.

spectroscopic variable
  ورتنده‌ی ِ بیناب‌نمایی   
vartande-ye binâbnemâyi

Fr.: variable spectroscopique   

A → variable star that displays changes in its → spectrum. In such stars line intensities may vary and new lines may appear. Examples include → AG Carinae, HD 108, HD 191612, and HD 148937.

spectroscopic; → variable.


Fr.: variable   

Something that may or does vary. → variable star.
Math.: A symbol, usually a letter, which in a mathematical or logic expression represents any member of a set of possible values or possible objects.

M.E., from O.Fr. variable, from L. variabilis "changeable," from variare "to change," → vary.

Vartandé agent noun from vartidan "to change," → vary.

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