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

A process whereby in a rotating, non-solid system matter is displaced toward (→ accretion) or away from (→ mass loss) the rotation center. See also → magnetorotational instability.

→ angular; → momentum; → transfer.

A semi-conductor device that relays stored charges positioned at predetermined locations, such as charge-coupled or charge-injection devices.

→ charge; → transfer; → device.

Fraction of the original charge which is successfully transferred from one pixel to the next in one CCD cycle.

→ charge; → transfer; → efficiency.

The → conversion of one → form of energy into another, or the movement of energy from one place or system to another.

→ energy; → transfer.

The spontaneous transportation of heat through matter, from a region of higher temperature to a region of lower temperature.

→ heat; → transfer.

An → orbital maneuver using two timed engine impulses to move a spacecraft between two coplanar circular orbits. It is performed through an elliptic orbit which is tangent to both circles at their periapses (→ periapsis).

→ Hohmann transfer orbit.

An elliptical orbit that is the most economical path for a spacecraft to take from one planet to another. In the case of Earth-Mars travel, the desired orbit's → perihelion will be at the distance of Earth's orbit, and the → aphelion will be at the distance of Mars' orbit. The portion of the solar orbit that takes the spacecraft from Earth to Mars is called its trajectory. Earth and Mars align properly for a Hohmann transfer once every 26 months. → Hohmann transfer.

Named after Walter Hohmann (1880-1945), German engineer, who developed basic principles and created advanced tools necessary for the conquest of space. In 1925 he published The Attainability of the Heavenly Bodies in which he described the mathematical principles that govern space vehicle motion, in particular spacecraft transfer between two orbits.

The process in which the evolved member of a close binary system passes gaseous material to its companion star.

→ mass; → transfer.

A measure of the ability of an optical system to reproduce (transfer) various levels of detail from the object to the image, as shown by the degree of contrast (modulation) in the image. → optical transfer function.

→ modulation; → transfer; → function.

The function that provides a full description of the imaging quality of an optical system. A combination of the → modulation transfer function (MTF) and the → phase transfer function (PTF) , the OTF describes the spatial (angular) variation as a function of spatial (angular) frequency.

→ optical; → transfer; → function.

A measure of the relative phase in the image as function of frequency. It is the phase component of the → optical transfer function. A relative phase change of 180°, for example, results in an image with the black and white areas reversed.

→ phase; → transfer; → function.

→ radiative transfer.

→ radiation; → transfer.

→ radiative transfer equation.

→ radiation; → transfer; → equation.

The process by which the → electromagnetic radiation passes through a medium that may contain any combination of → scatterers, → absorbers, and → emitters.

→ radiative; → transfer.

The equation that describes the → radiative transfer. It states that the → specific intensity of radiation I_σ during its propagation in a medium is subject to losses due to → extinction and to → gains due to → emission: dI_σ/dx = - μ_σ . I_σ + ρ . j_σ, where x is the coordinate along the → optical path, μ_σ is the → extinction coefficient, ρ is the mass → density, and j_σ is the → emission coefficient per unit mass.

→ radiative; → transfer; → equation.

1) The conveying of something or energy from one place or position to another.
→ charge-transfer device; → energy transfer; → heat transfer; → optical transfer function; → radiative transfer; → radiative transfer equation.
2a) To convey or pass from one place to another.
2b) To copy information or images from one place or object to another.

M.E. transferren (v.), from L. transferre "to carry over, transfer, translate," from → trans- "across" + ferre "to carry;" cognate with Pers. bordan "to carry, transport;" Mid.Pers. burdan; O.Pers./Av. bar- "to bear, carry," barəθre "to bear (infinitive);" Skt. bharati "he carries;" Gk. pherein "to carry;" PIE base *bher- "to carry."

Tarâvaž, from tarâ-, → trans- "across," + važ, variant vâz (in parvâz), Av. vaz- "to draw, guide; bring; possess; fly; float," vazaiti "guides, leads" (cf. Skt. vah- "to carry, drive, convey," vahati "carries," pravaha- "bearing along, carrying," pravāha- "running water, stream, river;" L. vehere "to carry;" O.E. wegan "to carry;" O.N. vegr; O.H.G. weg "way," wegan "to move," wagan "cart;" M.Du. wagen "wagon;" PIE base *wegh- "to drive;" see also → flight).

The mathematical relationship between the output of a control system and its input: for a linear system, it is the Laplace transform of the output divided by the Laplace transform of the input under conditions of zero initial-energy storage.

→ transfer; → function.