Fr.: aberration elliptique
An act or instance of emigrating; a body of emigrants; emigrants collectively.
Verbal noun of → emigrate.
energy generation equation
hamugeš-e âzâneš-e kâruž
Fr.: équation de génération d'énergie
energy generation rate
nerx-e âzâneš-e kâruž
Fr.: taux de génération d'énergie
Of a stellar → nuclear fusion, the energy produced per unit mass per unit time, usually denoted ε (erg g-1s-1). The general form of the energy generation equation is: ε = ε0ρλTν, where ε0, ρ, and λ are constants over some efficiently restricted range of → temperature T, → density ρ, and → chemical composition. The temperature exponent ν is about 4, 15, and 40 for → proton-proton chain, → CNO cycle, and → triple alpha process, respectively.
The physical process by which a liquid is transformed to the gaseous state, usually by means of heat; the opposite of → condensation. Also called vaporization.
Boxârš, verbal noun of boxâridan "to evaporate," from boxâr, → vapor.
1) An act or instance of exploring or investigating; examination.
Verbal noun of → explore.
extreme mass ratio inspiral (EMRI)
forupicé bâ vâbar-e ostom-e jerm
Fr.: orbite plongeante d'un trou noir binaire, au rapport de masse extrême
A compact stellar remnant (e.g., a → white dwarf, → neutron star, or → black hole) that undergoes → inspiral into a much more massive object (→ supermassive black hole found → galactic centers). EMRIs are potential sources of low-frequency → gravitational waves. Predictions of the EMRI event rates span a wide range, from ~ 10-9 to 10-6 yr-1 per galaxy (Merritt et al. 2011, Physical Review D 84, 044024). See also → resonant relaxation.
1) The act of federating or uniting in a league.
Verbal noun of → federate.
Fr.: calibration de flux
The → calibration of the flux received by a detector in terms of absolute units.
Fr.: rapport focal
The ratio of the → focal length of a reflecting surface or lens to its effective diameter, i.e. to its → aperture. The smaller the focal ratio, the smaller the image scale and the more luminous the image for a given aperture.
vâbar-e gâz bé qobâr
Fr.: rapport gaz/poussière
The mass ratio of gas to dust. It amounts to approximately 100 in the → interstellar medium, but may vary in → molecular clouds and → circumstellar disks due to dust → grain evaporation, → dust settling, → condensation of gas, etc. The gas-to-dust ratio depends on the → metallicity. It is larger in galaxies with lower metallicity.
Verbal noun of → generate.
roxgard-e hendesi (#)
Fr.: libration géométrique
Libration resulting from changes in the location of the observer with respect to body. More specifically, a lunar libration motion that results from the Earth based observer seeing the Moon from different directions at different times. There are three types of geometrical libration: → libration in longitude, → libration in latitude, and → diurnal libration. See also → physical libration.
Fr.: nombre d'or
If a line segment is divided into a larger subsegment (a) and a smaller subsegment (b), when the larger subsegment is related to the smaller exactly as the whole segment is related to the larger segment, i.e. a/b = (a + b)/a. The golden ratio, a/b is usually represented by the Greek letter φ. It is also known as the divine ratio, the golden mean, the → golden number, and the golden section. It was believed by Greek mathematicians that a rectangle whose sides were in this proportion was the most pleasing to the eye. Similarly, the ratio of the radius to the side of a regular → decagon has this proportion. The numerical value of the golden ratio, given by the positive solution of the equation φ2 - φ - 1 = 0, is φ = (1/2)(1 + √5), approximately 1.618033989. The golden ratio is an → irrational number. It is closely related to the → Fibonacci sequence.
Fr.: évaporation des grains
Conversion of dust grains into smaller grains due to high environmental temperatures.
šetâb-e gerâneši (#)
Fr.: accélération gravitationnelle
The acceleration caused by the force of gravity. At the Earth's surface it is determined by the distance of the object form the center of the Earth: g = GM/R2, where G is the → gravitational constant, and M and R are the Earth's mass and radius respectively. It is approximately equal to 9.8 m s-2. The value varies slightly with latitude and elevation. Also known as the → acceleration of gravity.
Fr.: calibration hélium-argon
A wavelength calibration of astronomical spectra using a helium-argon light source.
Fr.: collaboration HESS
hidreš, âbeš (#)
The process of combining with → water.
Verbal noun of → hydrate.
bâzsâzi-ye vine, ~ tasvir (#)
Fr.: restauration d'image
The process by virtue of which the original image can be created by removing the blurring and the noise that occur during image formation.