An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



Number of Results: 9 Search : elliptical
core elliptical galaxy
  کهکشان ِ بیضی‌گون ِ مغزه‌دار   
kahkešân-e beyzigun-e maqzedâr

Fr.: galaxie elliptique à coeur   

An → elliptical galaxy that displays a → surface brightness profile with a distinct break from a steep outer slope to a shallower inner → cusp. Core profiles mainly occur in very luminous elliptical galaxies and are considered the result of dissipation-less → mergers of two galaxies that have central → supermassive black holes (S. P. Rusli et al., 2013, AJ 146, 160).

core; → elliptical; → galaxy.

dwarf elliptical galaxy
  کهکشان ِ بیضی‌گون ِ کوتوله   
kahkašân-e beyzigun-e kutulé (#)

Fr.: galaxie elliptique naine   

A galaxy that is much smaller than other members of the elliptical class; it is designated as dE. A subtype of dwarf ellipticals is called a → dwarf spheroidal galaxy (dSph). The basic characteristics of the class are low surface brightness and smooth light distribution. They range in luminosity from that of the faintest dSph galaies MV ~ -9 to about -17. In the → Local Group there are 19 known dEs. They are very common in → galaxy clusters.

dwarf; → elliptical; → galaxy.

beyzigun (#)

Fr.: elliptique   

Pertaining to or having the shape of a geometric ellipse.

elliptic; → -al.

elliptical galaxy
  کهکشان ِ بیضی‌گون   
kahkašân-e beyzigun (#)

Fr.: galaxie elliptique   

A galaxy whose structure is smooth without spiral arms and ellipsoidal in shape. Ellipticals are redder than spirals of similar mass. Giant ellipticals contain over 1012 solar masses, whereas dwarf ellipticals have masses as low as 107 solar masses.

elliptical; → galaxy.

elliptical polarization
  قطبش ِ بیضی‌گون   
qotbeš-e beyzigub

Fr.: polarization elliptique   

The → polarization of an → electromagnetic radiation in which the electric vector at any point in the path of the beam describes an ellipse in a plane perpendicular to the propagation direction. Elliptical polarization results from the combination of two perpendicular → linearly polarized waves whose → phase difference is other than 0, 90, or 180°. The form of the ellipse is determined by the amplitudes of the component waves and the phase difference. → Linear polarization and → circular polarization can be considered as limiting cases of elliptical polarization.

elliptical; → polarization.

elliptically polarized light
  نور ِ قطبیده‌ی ِ بیضی‌گون   
nur-e qotbide-ye beyzigun

Fr.: lumière polarisée elliptiquement   

Light exhibiting → elliptical polarization.

elliptic; → polarized; → light.

power-law elliptical galaxy
  کهکشان ِ بیضی‌گون با قانون ِ توانی   
kahkešân-e beyzigun bâ qânun-e tavâni

Fr.: galaxie elliptique en loi de puissance   

An → elliptical galaxy whose → surface brightness can be approximated by a single → power law at small radii (r ≤ 10-20''). More modern interpretations have emphasized that these profiles can be better understood as the inward continuation of the galaxy's overall → Sersic profile, usually modified by an additional, nuclear-scale stellar component (S. P. Rusli et al., 2013, AJ 146, 160).

power; → law; → galaxy.

Sagittarius Dwarf Elliptical Galaxy
  کهکشان ِ کوتوله‌ی ِ بیضی‌گون ِ نیم‌اسب   
kahkešân-e kutule-ye beyzigun-e nimasb

Fr.: galaxie naine elliptique du Sagittaire   

A satellite galaxy of the Milky Way discovered only in 1994 since most of it is obscured by the Galactic disc. At only 50,000 light years distant from our Galaxy's core, it is travelling in a polar orbit around the Galaxy. Our Galaxy is slowly devouring it, as evidenced by a filament which stretches around the Milky Way's core like a gossamer loop. It is only about 10,000 light-years in diameter, in comparison to the Milky Way's diameter of 100,000 light years. It is populated by old yellowish stars has four known globular clusters: M54, Arp 2, Terzan 7, and Terzan 8. It should not be confused with the → Sagittarius Dwarf Irregular Galaxy.

Sagittarius; → dwarf; → elliptical; → galaxy.

Sculptor Dwarf Elliptical Galaxy
  کهکشان ِ کوتوله‌ی ِ بیضی‌گون ِ پیکرتراش   
kahkešân-e kutule-ye beyzigun-e Peykartarâš

Fr.: galaxie naine elliptique du Sculpteur   

A → dwarf elliptical galaxy that is a satellite of our → Milky Way. It lies about 285,000 → light-years away in the constellation → Sculptor, and has an → absolute magnitude of -11.28 and a mass of about 3 million → solar masses. The Sculptor Dwarf is a → metal-deficient galaxy containing only 4 percent of the oxygen and carbon elements in our own Galaxy.

Sculptor; → dwarf; → elliptical; → galaxy.