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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 14 Search : halo
blue halo star
  ستارگان ِ آبی ِ هاله   
setâregân-e âbi-ye hâlé

Fr.: étoiles bleues du halo   

A star belonging to a variety of stars located above the → horizontal branch and blueward of the → red giant branch in the → Hertzsprung-Russell diagram of the → halo population.

blue; → halo; → star.

Setâregân plural of setâré, → star, âbi, → blue, hâlé, → halo.

core-halo galaxy
  کهکشان ِ مغزه-هاله   
kahkešân-e maqzé-hâlé

Fr.: galaxie cœur-halo   

A radio galaxy characterized by an emission "halo" surrounding a more intense "core". About 20% of the known extended radio sources are of the core-halo type.

core; → halo; → galaxy.

dark matter halo
  هاله‌ی ِ ماده‌ی ِ تاریک   
hâle-ye mâde-ye târik (#)

Fr.: halo de matière sombre   

A vast region surrounding a galaxy where dynamical tracers reveal a large amount of → hidden mass. The halo has considerable mass but relatively low luminosity, suggesting the presence of a lot of → dark matter.

dark; → matter; → halo.

Galactic halo
  هاله‌ی ِ کهکشان   
hâle-ye kahkešân

Fr.: halo galactique   

A roughly spherical aggregation of → globular clusters, as well as the oldest stars and unseen mass that surrounds the Galaxy.

galactic, → halo.

halo
  هاله   
hâlé (#)

Fr.: halo   

1) Meteo.: Rings or arcs that seem to encircle the sun or moon and are the result of the refraction of light through the ice crystals that make up cirrus clouds.
2) → halo of galaxy.

Halo, from L. (acc.) halo, from Gk. halos "ring of light around the sun or moon."

Hâlé, loanword from Ar.

halo occupation distribution (HOD)
  واباژش ِ هگش ِ هاله   
vâbâžeš-e hageš-e hâlé

Fr.: distribution d'occupation de halo   

The → probability distribution of the → number of galaxies that a host → dark matter halo of a given mass contains. HOD is a powerful theoretical frame to populate dark matter halos with luminous galaxies. More specifically, it describes the bias between galaxies and dark matter by specifying (a) the probability P(N|M) that a halo of → virial mass M contains N galaxies of a particular class and (b) the relative spatial and velocity distributions of galaxies and dark matter within halos.

halo; → occupation; → distribution.

halo of galaxy
  هاله‌ی ِ کهکشان   
hâle-ye kakekašân (#)

Fr.: halo de galaxie   

The diffuse, nearly spherical cloud of stars and → globular cluster s that surrounds a → spiral galaxy.

halo; → galaxy.

halo of the Galaxy
  هاله‌ی ِ کهکشان   
hâle-ye kakekašân (#)

Fr.: halo de la Galaxie   

The → halo of galaxy belonging to our → Milky Way.

halo; → galaxy.

halo population
  پُرینش ِ هاله   
porineš-e hâlé

Fr.: population du halo   

Old stars with very low metallicities (→ metallicity) found in the → halo of the Galaxy. Also called → population II star.

halo; → population.

Halo ring
  حلقه‌ی ِ هاله، ~ هاله‌وار   
halqe-ye hâlé, ~ hâlevâr

Fr.: anneau de halo   

A faint, wide ring around → Jupiter that has the shape of a doughnut. It is about 22,800 km wide and about 20,000 km thick. This ring starts at 100,000 km from the center of Jupiter. The outer edge of the Halo merges into the → Main ring.

halo; → ring.

halogen
  هالوژن   
hâložen (#)

Fr.: halogène   

A member of a group of five chemical elements having closely related and similar properties. The halogens are: fluorine, chlorine, iodine, bromine, and astatine. They make up Group 17 of the → periodic table and can be found on the left-hand side of the → noble gases.

From Gk. halo- prefix from Gk. hals "salt" + → -gen.

hydrostatic halo
  هاله‌ی ِ هیدر-ایستا   
hâle-ye hidristâ

Fr.: halo hydrostatique   

A model of the → Milky Way galaxy in which the → Galactic halo (composed of → gas, → magnetic fields, and → cosmic rays) is assumed to be in → hydrostatic equilibrium. Parker (1966) presented the first study of stability considerations between gas, magnetic fields and cosmic rays in an equilibrium configuration. He found that it is difficult to maintain a stable configuration due to magnetohydrodynamic self-attraction (→ Parker instability). Subsequent works taking into account turbulent motions showed that turbulent pressure can mitigate the influence of Parker instabilities. This enabled new attempts to find conditions under which a stable equilibrium configuration of the Galaxy could exist.

hydrostatic; → halo.

massive halo
  هاله‌ی ِ پرجرم   
hâle-ye porjerm

Fr.: halo massif   

Spheroidal distribution of dark matter surrounding a galaxy.

massive; → halo.

Moon halo
  هاله‌ی ِ ماه   
hâle-ye mâh (#)

Fr.: halo de la lune   

Same as → lunar halo.

Moon; → halo.