"niruhâ-ye nâgerâneši" (#)
Fr.: "forces non-gravitationnelles"
The forces of jets from a comet's nucleus that can cause a rocket-like effect and alter a comet's direction of motion slightly.
→ non-; → gravitational; → force.
Einstein's gravitational constant
pâyâ-ye gerâneši-ye Einstein (#)
Fr.: constante gravitationnelle d'Einstein
The coupling constant appearing in → Einstein's field equations, expressed by: κ = 8πG/c4, where G is the Newtonian → gravitational constant and c the → speed of light.
→ einstein; → gravitational; → constant.
Gaussian gravitational constant
pâyâ-ye gerâneši-ye Gauss
Fr.: constante gravitationnelle de Gauss
The constant, denoted k, defining the astronomical system of units of length (→ astronomical unit), mass (→ solar mass), and time (→ day), by means of → Kepler's third law. The dimensions of k2 are those of Newton's constant of gravitation: L 3M -1T -2. Its value is: k = 0.01720209895.
→ Gaussian; → gravitational; → constant.
Of or relating to or caused by → gravitation.
Adj. of → gravitation.
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.
→ gravitational; → acceleration.
Fr.: attraction gravitationnelle
The force that pulls material bodies toward one another because of → gravitation.
→ gravitational; → attraction.
rombeš-e gerâneši (#)
Fr.: effondrement gravitationnel
Collapse of a mass of material as a result of the mutual → gravitational attraction of all its constituents.
→ gravitational; → collapse.
pâyâ-ye gerâneši (#)
Fr.: constante gravitationnelle
A fundamental constant that appears in → Newton's law of gravitation. It is the force of attraction between two bodies of unit mass separated by unit distance: G = 6.673 x 10-8 dyn cm2 g-2 or 6.673 x 10-8 cm3s-2g-1, or 6.673 x 10-11 N m2 kg-2 or 6.673 x 10-11 m3s-2kg-1. It was first measured in 1798 by Henry Cavendish (1731-1810), 71 years after Newton's death. Same as the → Newtonian constant of gravitation.
→ gravitational; → constant.
Fr.: contraction gravitationnelle
Decrease in the volume of an astronomical object under the action of a dominant, central gravitational force.
→ gravitational; → contraction.
gravitational coupling constant
pâyâ-ye jafsari-ye gerâneši
Fr.: constante de couplage gravitationnel
The dimensionless gravitational constant defined as the gravitational attraction between pair of electrons and normally given by: αG = (Gme2) / (ħc) = (me / mP)2 ~ 1.7518 × 10-45, where ħ is → Planck's reduced constant, c the → speed of light, me is the → electron mass, and mP is the → Planck mass.
→ gravitational; → coupling; → constant.
Fr.: rencontre gravitationnelle
An encounter in which two moving bodies alter each other's direction and velocity by mutual → gravitational attraction.
→ gravitational; → encounter.
Fr.: énergie gravitationnelle
Same as → gravitational potential energy.
→ gravitational; → energy.
tarâzmandi-ye gerâneši (#)
Fr.: équilibre gravitationnel
The condition in a celestial body when gravitational forces acting on each point are balanced by some outward pressure, such as radiation pressure or electron degeneracy pressure, so that no vertical motion results.
→ gravitational; → equilibrium.
meydân-e gerâneši (#)
Fr.: champ gravitationnel
The region of space in which → gravitational attraction exists.
→ gravitational; → field.
niru-ye gerâneši (#)
Fr.: force gravitationnelle
The weakest of the four fundamental forces of nature. Described by → Newton's law of gravitation and subsequently by Einstein's → general relativity.
→ gravitational; → force.
nâpâydâri-ye gerâneši (#)
Fr.: instabilité gravitationnelle
The process by which fluctuations in an infinite medium of size greater than a certain length scale (the Jeans length) grow by self-gravitation.
→ gravitational; → instability.
Fr.: interaction gravitationnelle
Mutual attraction between any two bodies that have mass.
→ gravitational; → interaction.
adasi-ye gerâneši (#)
Fr.: lentille gravitationnelle
A concentration of matter, such as a galaxy or a cluster of galaxies, that bends light rays from a background object, resulting in production of multiple images. If the two objects and the Earth are perfectly aligned, the light from the distant object appears as a ring from Earth. This is called an Einstein Ring, since its existence was predicted by Einstein in his theory of general relativity.
→ gravitational; → lens.
gravitational lens equation
hamugeš-e adasi-ye gerâneši
Fr.: équation de lentille gravitationnelle
The main equation of gravitational lens theory that sets a relation between the angular position of the point source and the observable position of its image.
→ gravitational; → lens; → equation.
Fr.: effet de lentille gravitationelle
The act of producing or the state of a → gravitational lens.
→ gravitational; → lensing.