homogeneous linear differential equation
hamugeš-e degarsâne-yi-ye xatti hamgen
Fr.: équation différentielle linéaire homogène
A → linear differential equation if the right-hand member is zero, Q(x) = 0, on interval I.
âšubnâki-ye hamgen (#)
Fr.: turbulence homogène
→ Turbulence in which spatial derivatives of all mean turbulent quantities are negligible.
giti-ye hamgen (#)
Fr.: Univers homogène
A model Universe which is homogeneous and → isotropic on large scales. It is modeled by a → Robertson-Walker cosmology. A homogeneous Universe is filled with a constant density and negligible pressure. Any small spatial region is characteristic for the whole Universe.
Fr.: molécule homonucléaire
Fr.: nébuleuse de l'Homoncule
A nebula of gas and dust (about 17" x 12" in size), which surrounds the massive star Eta Carinae and lies about 7500 light-years away. The surrounding material was ejected by the massive star in 1843 during its violent eruption, and is now expanding at about 500 km/sec.
Homunculus, "a diminutive human being; little man" (since the nebula resembled a small human to early observers), from L. homin-, homun-, homo "eartly being," humus "the earth" (cf. Pers. zamin "earth, ground," Mid.Pers. zamig "earth;" Av. zam- "the earth;" Skt. ksam; Gk. khthôn, khamai "on the ground;" PIE root *dh(e)ghom "earth") + → -ula, -ule; → nebula.
Miq, → nebula; âdamak "little man."
1) A curved or bent piece of metal or other hard material for catching,
holding, or hanging something.
M.E. hoke, O.E. hoc "hook, angle;" cf. M.Du. hoek, Du. haak, Ger. Haken "hook."
Qollab "a hook, a hooked device," probably ultimately from Proto-Ir. gart- "to turn;" cf. Pers. gard-, gardidan, gaštan "to turn, to wind;" cognate with dialectal qellidan "to roll."
qânun-e Hooke (#)
Fr.: loi de Hooke
The law stating that if a body is deformed the → strain
produced is directly proportional to the applied → stress.
If the elastic limit is not exceeded, the material returns to its original shape and
size on the removal of the stress. Hooke's law forms the basis of the theory of
Named after Robert Hooke (1635-1703), British scientist who described the relationship in 1676; → law.
Fr.: 1) sautiller, sauter; 2) sautillement, saut
1) To move by a quick springy leap or in a series of leaps.
(Of a person) Move by jumping on one foot. (Of a bird or other animal) move by jumping
with two or all feet at once.
M.E. hoppen; O.E. hoppian; cognate with Ger. hopfen, O.N. hoppa.
Kopidan, from kop; cf. (Bašâgardi) kup, (Lârestâni) komp, (Bardesiri) gopak, (Sistâni) job, (Kermâni) pok, pokidan "jump, leap."
1) An imaginary circle that delimits the sky and the Earth.
From O.Fr. orizon, from orizonte, from L. horizontem (nom. horizon), from Gk. horizon kyklos "bounding circle," from horizein "bound, limit, divide, separate," from horos "boundary."
Ofoq, from Ar.
horizon coordinate system
râžmân-e hamârâhâ-ye ofoqi
Fr.: coordonnées horizontales
Fr.: problème de l'horizon
A problem with the standard cosmological model of the Big Bang related to the observational fact that regions of the Universe that are separated by vast distances nevertheless have nearly identical properties such as temperature. This contradicts the fact that light moves with a finite speed and, as a result, certain events which occur in the Universe are completely independent of each other. Inflationary cosmology offers a possible solution.
Fr.: coordonnées horizontales
Same as → horizon coordinate system.
1) Of or pertaining to the → horizon.
horizontal branch (HB)
šâxe-ye ofoqi (#)
Fr.: branche horizontale
A set of roughly horizontal points in the → Hertzsprung-Russell diagram of a typical → globular cluster. It displays a stage of stellar evolution which immediately follows the → red giant branch (RGB) in stars with an initial mass < 1.2 Msun. When the star's ascent of the RGB is terminated by the → helium flash, it moves down to the HB. The star's → effective temperature on the HB is higher than it was on the RGB, but the luminosity is considerably less than at the helium flash. Usually HB stars have two energy sources: in addition to the → helium burning in their cores, they experience → hydrogen fusion in a surrounding shell. The thickness of the shell determines the color of the HB stars. A thin shell, involving low → opacity, makes the star look blue. The HB domain encompasses a very large effective temperature range with several members: → extreme HB, → blue HB, → RR Lyrae, → red HB, and → red clump stars. The locations depend on many parameters, including stellar mass, metallicity, age, helium abundance, and rotation.
horizontal branch star
setâre-ye šâxe-ye ofoqi
Fr.: étoile de la branche horizontale
A star lying on the → horizontal branch.
A type of → lunar eclipse that occurs when both the Sun and the eclipsed Moon can be observed at the same time. This is possible only when lunar eclipse occurs just before sunset or just after sunrise. At that case, both bodies will appear just above the horizon at nearly opposite points in the sky. Also called → selenelion and → selenehelion.
Fr.: parallaxe horizontale
The angle under which the radius of the Earth at the place of observation would be seen from a celestial body when it is in the horizon (at the instant of rising or setting). The amount varies with the latitude since the Earth is not exactly spherical, and is greatest at equator.
šekast-e ofoqi (#)
Fr.: réfraction horizontale
The angular distance of an object below the horizon when it appears to lie on the horizon.
In computer science, a scaling in which the processing power is increased/decreased by adding/removing nodes with similar resources. See also → vertical scaling.