An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 718
dark exposure
  نورداد ِ تاریکی   
nurdâd-e târiki

Fr.: pose d'obscurité   

A → CCD frame obtained with closed → shutters in the absence of any light source, in order to estimate the → dark current of the → detector.

dark; → exposure.

dark fringe
  فریز ِ تاریک   
fariz-e târik (#)

Fr.: frange noire   

One of the successive dark and light bands produced by diffraction or interference of light.

From O.Fr. frange, from V.L. *frimbia alteration by metathesis of L. fimbria "fringe, edge of garment."

Fariz, variants farviz, farâviz "fringe, edge of garment."

dark matter
  ماده‌ی ِ تاریک   
mâdde-ye târik (#)

Fr.: matière noire   

Matter that has no radiation and therefore cannot be detected directly, but whose presence can be inferred from dynamical phenomena produced by its gravitational influence. The existence of dark matter is deduced mainly from the rotational speeds of galaxies, velocities of galaxies in clusters, gravitational lensing by galaxy clusters, and the temperature distribution of hot gas in galaxies and clusters of galaxies. Dark matter plays also a central role in cosmic structure formation. There exists a large number of → non-baryonic dark matter candidates. They include, the hypothetical stable particles → WIMPs, → neutralinos, → axions, → gravitinos, etc. Among unstable candidates are gravitinos with mild R-parity violation and sterile neutrinos. See also → baryonic dark matter, → dark matter candidate.

The concept of dark matter was first introduced by J.H. Oort (1932, Bull. Astron. Inst. Netherlands, 6, 249), who studied the vertical motions of the stars in the solar neighborhood and found that the visible matter could account for at most 50% of the derived surface density. → dark; → matter.

dark matter annihilation
  نابودی ِ ماده‌ی ِ تاریک   
nâbudi-ye mâde-ye târik

Fr.: annihilation de la matière noire   

A hypothetical process whereby hypothetical → non-baryonic dark matter particles undergo → annihilation interactions with themselves. The process results in observable by-products such as high-energy photons, neutrinos, and other detectable particles. See also → dark matter decay.

dark; → matter; → annihilation.

dark matter candidate
  نامزد ِ ماده‌ی ِ تاریک   
nâmzad-e mâdde-ye târik (#)

Fr.: candidat matière noire   

A hypothetical physical entity capable of accounting for the corresponding observed phenomena involving → dark matter. → Non-baryonic dark matter candidates include → WIMPs, → neutralinos, → axions, → gravitinos. Among → baryonic dark matter candidates can be noted ordinary and heavy → neutrinos, clouds of → neutral hydrogen gas, and compact objects.

dark; → matter; → candidate.

dark matter decay
  تباهی ِ ماده‌ی ِ تاریک   
tabâhi-ye mâde-ye târik

Fr.: désintégration de la matière noire   

In theoretical models, the hypothetical transformation of a → non-baryonic dark matter particle when symmetry is violated at special physical conditions. Dark matter decay and → dark matter annihilation are expected to produce enormous amounts of energy in the form of gamma-rays, cosmic rays, etc.

dark; → matter; → decay.

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.

dark nebula
  میغ ِ تاریک   
miq-e târik

Fr.: nébuleuse sombre   

An interstellar cloud of absorbing matter whose dust particles obscure the light from stars beyond it and give the cloud the appearance of a dark, starless region.

dark; → nebula.

dark star
  ستاره‌ی ِ تاریک   
setâre-ye târik

Fr.: étoile noire, ~ sombre   

A hypothetical stellar object whose structure or evolution has been affected by → dark matter. Dark matter models predict that in the → early Universe dark matter (in the form of → WIMPs) should congregate and annihilate in the cores of → Population III stars. The result would be dark stars with properties very different from ordinary stars. The reason is that the presence of large amounts of dark matter during the formation of a star inhibits the collapse and can partially prevent further cooling of the gas beyond a certain critical point, well before a → main sequence object has formed. As a consequence, dark matter stars should be more massive, more luminous, and live longer than Pop. III stars, but would be cooler. The formation of dark stars could have had an impact on the → reionization history of the Universe (see, e.g., P. Scott, 2011, astro-ph/1101.1029, and references therein).

dark; → star.


Fr.: s'assombrir   

To become dark or darker. → darkening.

Verb of → dark.


Fr.: assombrissement   

The act or process of becoming dark or darker. → limb darkening.

Verbal noun of of → darken.

dâdehâ (#)

Fr.: données   

Items of information.

L. data, plural of → datum.

Dâdehâ, plural of dâdé, → datum.

data access layer (DAL)
  لایه‌ی ِ دسترسی به داده‌ها   
lâye-ye dastrasi bé dâde-hâ

Fr.: couche accès aux données   

In the → software architecture, the code that deals with reading from or writing to the data store, hiding its nature and complexity.

data; → access; → layer.

data acquisition
  الفنجش ِ داده‌ها   
alfanješ-e dâdehâ

Fr.: acquisition de données   

The process of controlling telescope operations during observation and obtaining data.

data; acquisition, from L. acquisitionem, from acquirere "get in addition," from → ad- "extra" + quærere "to search for, obtain."

Alfanješ, verbal noun of alfanjidan (variant alfaqdan) "to acquire, get," Bactrian αλφανζ "to acquire," Sogdian δβ'yz "to acquire, gain, get" (Cheung 2007); → data.

data analysis
  آنالس ِ داده‌ها، آناکاوی ِ ~   
ânâlas-e dadehâ, ânâkâvi-ye ~

Fr.: analyse de données   

The evaluation of reduced data; → data reduction.

data; → analysis.

data archive
  بایگانی ِ داده‌ها   
bâygâni-ye dâdehâ (#)

Fr.: archive de données   

Any extensive record or collection of data, observational (usually obtained with a particular instrument) or theoretical (grid of models usually regarding a particular branch of astrophysics).

data; → archive.

data bank
  بانک ِ داده‌ها، داده بانک   
bânk-e dâdehâ, dâdé bânk (#)

Fr.: banque de données   

A set of data related to a given subject and organized in such a way that it can be consulted by users.

data; bank, from M.Fr. banque, from O.It. banca "table," because of "the moneylender's exchange table," from P.Gmc. *bankiz (O.H.G. bank "bench").

Bânk, from Fr. banque, see above; dâdehâ, plural of dâdédatum.

data mining
  کان‌کاوی ِ داده‌ها، داده کاوی   
kânkâvi-ye dâde-hâ, dâdé kâvi

Fr.: exploration de données   

The process of digging through large quantities of raw data stored in → databases to uncover new characteristics, patterns, and correlations using various automatic or semi-automatic statistical/mathematical means.

data; mining, from mine, M.E., from O.Fr. mine, probably from a Celtic source.

Kânkâvi, literally "digging mine," from kân "mine," related to kandan "to dig" (Mid.Pers. kan, qn; O.Pers. ka(n) "to dig;" Av. kan- "to dig;" cf. Skt. khan- "to dig") + kâvi from kâvidan/kâftan "to split; to dig" (Mid.Pers. kandan "to dig;" cf. Gk. skaptein "to dig;" L. scabere "to scratch, rub").

data model
  مدل ِ داده‌ها   
model-e dâde-hâ

Fr.: modèle de données   

An abstract entity that describes the structure of → database by including the formal description of the information system used in the database.

data; → model.

data number (DN)
  شمار ِ داده‌ها   
šomâr-e dâdehâ


Unit of the analog-to-digital conversion system of a CCD apparatus. For example a 16 bit system may use a maximum of 65536 DN. The acronym ADU, for analog-to-digital unit, is also used.

data; → number.

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