An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 36 Search : hole
binary black hole
  سیه‌چال ِ درین   
siyah câl-e dorin

Fr.: trou noir binaire   

A → binary system consisting of two → black holes in close orbit around each other. Same as → black hole binary.

binary; → black; → hole.

binary supermassive black hole
  سیه‌چال ِ ابر-پرجرم ِ درین   
siyah-câl-e abar-porjerm-e dorin

Fr.: trou noir supermassif double   

A → dual supermassive black hole whose components are separated by a few parsecs.

binary; → supermassive; → black; → hole.

black hole
  سیه‌چال، ~ سوراخ   
siyah câl (#), ~ surâx (#)

Fr.: trou noir   

A fantastically → compact object, predicted by the theory of → general relativity, whose → gravity is so powerful that not even light can escape from it. A black hole forms when matter → collapses to → infinite  → density, producing a → singularity of infinite → curvature in the fabric of → space-time. Each black hole is surrounded by an → event horizon, at which the → escape velocity is the → speed of light. The → Schwarzschild radius for the Sun is about 3 km and for the Earth about 1 cm. There is observational evidence for black holes on a remarkable range of scales in the Universe: → stellar black hole, → intermediate-mass black hole, → primordial black hole, → mini black hole, → supermassive black hole, → Schwarzschild black hole, → Kerr black hole.

Historically, the Newtonian concept of such a celestial body appeared at the end of the 18th century when light was shown to have particle characteristics. In fact the English geologist John Mitchell (1724-1793) and French mathematician and astronomer Pierre Simon Laplace (1749-1827), independently, suggested that regions of space, where gravitational attraction was so strong that not even light could escape, may exist in the Universe. However, the term black hole was coined in 1967 by the Princeton physicist John A. Wheeler (1911-2008); → black; → hole.

black hole binary
  سیه‌چال ِ درین   
siyah câl-e dorin

Fr.: trou noir binaire   

A → binary system in which each component is a → black hole. The binary's evolution can be divided into three stages: → inspiral, → merger, and → ringdown.

black; → hole; → binary.

black hole candidate
  نامزد ِ سیه‌چال   
nâmzad-e siyah câl (#)

Fr.: candidat trou noir   

An object that seems likely to be a → black hole, but waits for more observational confirmations.

black; → hole; → candidate.

black hole corona
  تاج ِ سیه‌چال   
tâj-e siyah câl

Fr.: couronne du trou noir   

A spherical volume of hot plasma over a broader → accretion disk around a → black hole. The observation of energetic X-ray emission from black holes, which is inconsistent with → thermal emission from an accretion disk, is attributed to the presence of a putative hot corona. It has been widely postulated that the → hard X-rays are the product of → inverse Compton scattering of seed photons from accretion disks by hot ccoronae (See, e.g., F.L. Vieyro et al., 2010, arXiv:1005.5398 and R. C. Reis & J. M. Miller, 2013, arXiv:1304.4947).

black; → hole; → corona.

black hole merger
  تشک ِ سیه‌چالها   
tašk-e siyah-câlhâ

Fr.: fusion de trous noirs   

The collision of two → black holes in a → binary black hole system once they come so close that they cannot escape each other's gravity. They will merge in an extremely violent event to become one more massive black hole. The merger would produce tremendous energy and send massive ripples, called → gravitational waves, through the → space-time fabric of the Universe. Such an event (called GW150914) was first detected by the → Laser Interferometer Gravitational-Wave Observatory (LIGO) on September 14, 2015. The initial black hole masses were 36 and 29 Msun which gave a final black hole mass of 62 Msun, with 3 Msun radiated in gravitational waves. The event happened at a distance of 1.3 billion → light-years from Earth (Abbott et al., 2016, Phys. Rev. Lett. 116, 061102). Black hole merger is preceded by → inspiral and followed by → ringdown.

black; → hole; → merger.

black hole surface gravity
  گرانی ِ رویه‌ی ِ سیه‌چال   
gerâni-ye ruye-ye siyah câl

Fr.: gravité de surface de trou noir   

The acceleration of gravity at the → event horizon of a → black hole. For a → Schwarzschild back hole it is given by κ = GM/RSch2 = c4/(4GM).

black; → hole; → surface; → gravity.

black hole's shadow
  سایه‌ی ِ سیه‌چال   
sâye-ye siyah-câl

Fr.: ombre de trou noir   

A gravitationally lensed image of a → black hole as seen by a distant observer if the black hole is in front of a bright background. According to → general relativity, photons circling the black hole slightly inside the boundary of the → photon sphere will fall down into the → event horizon, while photons circling just outside will escape to infinity. The shadow appears therefore as a rather sharp boundary between bright and dark regions and arises from a deficit of those photons that are captured by the event horizon. Because of this, the diameter of the shadow does not depend on the photons energy, but uniquely on the → angular momentum of the black hole. In a pioneering study, Bardeen (1973) calculated the shape of a dark area of a → Kerr black hole, that is, its "shadow" over a bright background appearing, for instance, in the image of a bright star behind the black hole.

black; → hole; → shadow.

circumblack-hole disk
  گرده‌ی ِ پیرا-سیه‌چال   
gerde-ye pirâ-siyah câl

Fr.: disque autour de trou noir   

An → accretion disk formed around a → black hole.

circum-; → black; → hole.

coronal hole
  سوراخ ِ هورتاجی   
surâx-e hurtâji

Fr.: trou coronal   

An area in the → solar corona which appears dark in X-rays and ultraviolet light. The gas density in these areas are very low, about 100 times less than that of coronal → active regions. The magnetic field lines in a coronal hole extend out into → interplanetary space rather than returning to the Sun's surface, as they do in other parts of the Sun (→ open magnetic field line). Ionized hot gas can escape easily along such a path, and this brings about high speed → solar wind streams.

coronal; → hole.

dual supermassive black hole
  سیه‌چال ِ ابر-پرجرم ِ دوگانه   
siyah-câl-e abar-porjerm-e dogâné

Fr.: trou noir supermassif double   

The outcome of a → merger process between two galaxies, each with its own central → supermassive black hole (SMBH), resulting in a remnant galaxy hosting two SMBHs. Simulations of → galaxy mergers show there should be lots of dual → active galactic nuclei (AGN) visible at less than 10 kpc separations. As of 2015 more than 100 known dual supermassive black holes have been found. See also → binary supermassive black hole.

dual; → supermassive; → black; → hole.

  سوراخ، چاله، چال   
surâx (#), câlé (#), câl (#)

Fr.: trou   

1) General: An opening through something; an area where something is missing; a serious discrepancy.
2) Astro.: → black hole; → coronal hole.
3) Electronics: The absence of an electron in the valency structure of a crystalline semiconductor, behaving like a positive charge carrier.

O.E. hol "orifice, hollow place," from P.Gmc. *khulaz (cf. O.H.G. hol, M.Du. hool, Ger. hohl "hollow"), from PIE base *kel- "to cover, conceal." → cell.

Surâx "hole," from Mid.Pers. sûlâk "whole, aperture," Av. sūra- "hole;" cf. Gk. koilos "hollow," L. cava "cave," cavus "hollow;" PIE base keuə- "to swell; vault, hole."
Câlé, câl "hole," from câh "a well, pit," from Mid.Pers. câh "a well;" Av. cāt- "a well," from kan- "to dig," uskən- "to dig out" (O.Pers. kan- "to dig," akaniya- "it was dug;" Mod.Pers. kandan "to dig"); cf. Skt. khan- "to dig," khanati "he digs," kha- "cavity, hollow, cave, aperture."

hole injection
  درشانش ِ سوراخ، ~ چاله   
daršâneš-e surâx, ~ câlé

Fr.: injection de trou   

The injection of holes in a semiconductor which can be produced by application of a sharp conducting point in contact with an n-type semiconductor.

hole; → injection.

Huge Hole
  سوراخ ِ کلان   
surâx-e kalân

Fr.: Trou Géant   

A region of the Universe, nearly a billion light-years across, mostly devoid of stars, gas, other normal matter, and also → dark matter. Situated at about 6 billion light-years from us, in projection on the the constellation → Eridanus, it shows up as a particularly cold region in the map of the → cosmic microwave background (CMB) radiation. Observations made using the → Very Large Array (VLA) radio telescope show a relative absence of matter in that area.

Huge, from M.E. huge, hoge, from O.F. ahuge, ahoge "enormous," from a variant of → ad- + hoge "height," → high; → hole.

Surâx, → hole; kalân "great, large, bulky."

intermediate-mass black hole (IMBH)
  سیه‌چال ِ میان‌جرم   
siyah câl-e miyân jerm

Fr.: trou noir de masse intermédiaire   

A → black hole with a mass in the range 102-104 solar masses. IMBHs may form as the result of multiple → mergers of smaller objects in the centers of dense stellar clusters in the present universe, assuming → mass loss from → stellar winds is not significant. They may also arise from the evolution of → very massive stars early in the history of the Universe, forming black hole "seeds" in the centers of massive halos (the precursors of the galaxies we see today) early in the history of the Universe, to redshifts z > 10. Currently the best observational evidence for IMBHs comes from models of ultraluminous X-ray sources (See, e.g., J. M. Centrella et al. 2010, astro-ph/1010.5260).

intermediate; → mass; → black; → hole.

Kerr black hole
  سیه‌چال ِ کر   
siyah câl-e Kerr (#)

Fr.: trou noir de Kerr   

A → black hole that possesses only mass (not electric charge) and rotates about a central axis. It has an → ergosphere and a → stationary limit.

Named after the New Zealand mathematician Roy P. Kerr (1934-) who, in 1963, was the first to solve the → field equationss of Einstein's theory of → general relativity for a situation of this kind; → black hole.

Kerr-Newman black hole
  سیه‌چال ِ کر-نیومن   
siyah câl-e Kerr-Newman

Fr.: trou noir de Kerr-Newman   

A rotating charged black hole. Compare with the → Kerr black hole and the → Reissner-Nordstrom black hole.

Named after Roy P. Kerr and Ezra T. Newman (1929-) who in 1963 independently found this solution to Einstein's → field equations; → black; → hole.

  سوراخ ِ کلید   
surâx-e kelid (#)

Fr.: trou de serrure   

1) The hole in which a key of a lock is inserted.
2) → Keyhole Nebula.
3) A small, about 600 m wide, region of space close to the Earth where the Earth's gravity would perturb the trajectory of a passing → Near-Earth Object. The object will receive a gravitational push that will bring it back for a collision in the future. Also called resonance keyhole.

key; → hole.

Keyhole Nebula
  میغ ِ سوراخ ِ کلید   
miq-e surâx-e kelid

Fr.: Nébuleuse du Trou de Serrure   

A relatively small and dark cloud of molecules and dust seen silhouetted against the much brighter → Carina Nebula. It contains bright filaments of emitting hot gas and is roughly 7 → light-years in size.

keyhole; → nebula. The name was given by the English astronomer Sir John Herschel in the 19th century, because of the appearance of the nebula in low-resolution telescopes of that epoch.

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