An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 435 Search : ad
bad column
  ستون ِ بد   
sotun-e bad

Fr.: mauvaise colonne   

Column of a → CCD detector that does not correctly read out charge.

Bad, from M.E. badde, but the origin of the word is not clear; → column.

Sotun, → column; bad, from Mid.Pers. wad, maybe from Old Iranian *vata- "small;" cf. Scythian bata- "small, bad," Sogdian wtγy "suffer, sorrow."

Baily's beads
  مهره‌های ِ بیلی   
mohrehâ-ye Beyli (#)

Fr.: perles de Baily   

A phenomenon that occurs during a total eclipse of the Sun. Just prior to and after totality, sunlight shines through the lunar valleys on the Moon's limb, causing the dark face of the Moon to appear to be surrounded by a shining "necklace of pearls".

Baily, from Francis Baily (1774-1844), English amateur astronomer, who discovered the phenomenon during the solar eclipse of 1836. Beads "a necklace of beads or pearls; a rosary," from bead "a small, often round piece of material, such as glass, plastic, or wood, that is pierced for stringing or threading," from M.E. bede "rosary bead," from O.E. bed, bedu, gebed "prayer;" PIE *gwhedh- "to ask, pray".

Mohrehâ "beads," from mohré "a kind of small shell resembling pearls; glass or coral beads," cf. Khotanese mrâhe, may be related to morvârid, → pearl, + -hâ suffix of plurals.

band head
  باندسر، سر ِ باند   
bândsar, sar-e bând

Fr.: tête de bande   

A location on the spectrogram of a molecule at which the lines of a band stack.

Band head, from → band + head, from O.E. heafod "top of the body," also "upper end of a slope," also "chief person, leader," from P.Gmc. *khaubuthan, from PIE *kauput- "head" (cf. Skt. kaput-, L. caput "head," Lori kapu "head," kapulek "skull, middle of the head").

Bândsar, from → bând + sar "head," soru, sorun "horn," karnâ "a trumpet-like wind instrument" (originally made from animal horns), variant sornâ "a wind instrument;" Mid.Pers. sar "head," sru "horn;" Av. sarah- "head," srū- "horn, nail;" cf. Skt. śiras- "head, chief;" Gk. kara "head," karena "head, top," keras "horn;" L. cornu "horn," cerebrum "brain;" P.Gmc. *khurnaz (E. horn; Ger. Horn, Du. horen), from PIE *ker- "head, horn."

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.

blackbody radiation
  تابش ِ سیه‌جسم   
tâbeš-e siyah-jesm (#)

Fr.: rayonnement de corps noir   

The radiation emitted by a blackbody at a given → temperature. The → distribution of radiation with → wavelength is given by → Planck's blackbody formula or → Planck's radiation law.

blackbody; → radiation.

Bohr radius
  شعاع ِ بؤر   
šo'â'-e Bohr

Fr.: rayon de Bohr   

The radius of the orbit of the hydrogen electron in its ground state (0.529 Å).

Bohr; → radius.

Bondi-Hoyle accretion radius
  شعاع ِ فربال ِ بوندی-هویل   
šo'â'-e farbâl-e Bondi-Hoyle

Fr.: rayon de l'accrétion de Bondi-Hoyle   

In the → Bondi-Hoyle accretion process, the radius where the gravitational energy owing to star is larger than the kinetic energy and, therefore, at which material is bound to star. The Bondi-Hoyle accretion radius is given by RBH = 2 GM / (v2 + cs2) where G is the gravitational constant, M is the stellar mass, v the gas/star relative velocity, and cs is the sound speed.

Bondi-Hoyle accretion; → radius.

pahn (#)

Fr.: large   

Wide in extent from side to side.

M.E. bro(o)d, from O.E. brad; cf. O.N. breiðr, Du. breed, Ger. breit, Goth. brouþs.

Pahn "wide, broad," from Mid.Pers. pah(a)n; Av. paθana- "broad, wide, spacious;" PIE root *pete- "to spread;" cf. L. patere "to be open," Gk. petannynai "to spread out," petalon "a leaf."

broad-band photometry
  شیدسنجی ِ پهن-باند   
šidsanji-ye pahn-bând

Fr.: photométrie à bande large   

Photometric measurements carried out through filters with a band-width (about one-tenth the central wavelength) in the range 30-100 nm. Typical examples are Johnson photometry, Krons-Cousins RI photometry, and the six-color system.

broad; → band; → photometry.

broad-line radio galaxy (BLRG)
  رادیو‌کهکشان ِ پهن-خط   
radio kahkašân-e pahn-xatt

Fr.: galaxie radio à raies larges   

A radio galaxy that shows broad optical emission lines. → broad-line region.

broad; → line; → radio galaxy.

broad-line region (BLR)
  ناحیه‌ی ِ پهن-خط   
nâhiye-ye pahn-xatt

Fr.: région à raies larges   

The inner region of a → quasar or an → active galactic nucleus exhibiting broad → spectral lines which indicate ionized matter moving with speeds in excess of 10,000 km sec-1, probably due to the presence of an → accretion disk surrounding a → supermassive black hole. Also called Type I AGN. See also → obscuring torus.

broad; → line; → region.


Fr.: élargir   

To make or become broad or broader.


Pahnidan, from pahn, → broad, + -idan infinitive suffix.


Fr.: élargissement   

The act of making something wider. → instrumental broadening; → line broadening.

Broadening, from → broad + → -ing noun froming suffix.

Pahneš, from pahn (→ broad, present tense stem of pahnidan "to broaden" + -idan infinitive suffix) + verbal-noun suffix.

Canada-France-Hawaii Telescope (CFHT)
  تلسکوپ ِ کانادا-فرانسه-هاوایی   
teleskop-e Kânâdâ-Farânsé-Hâvâyi

Fr.: télescope Canada-France-Hawaii   

A 3.6 m optical/infrared telescope jointly owned and operated by the Canadian National Research Council (NRC), the French Centre National de la Recherche Scientifique (CNRS), and the University of Hawaii. It became operational in 1979. The observatory is located atop the summit of Mauna Kea, a 4200 m, dormant volcano located on the island of Hawaii. The Observatory headquarters is located in Waimea (also known as Kamuela by the US Postal Service). Situated at the low latitude of Hawaii (+19° 45'), there is a fairly large sky overlapping with that of the → European Southern Observatory (ESO)  → La Silla observatory (δ = -29° 15'). The point where an object is seen at the same → zenith distance from La Silla and from Mauna Kea, when it crosses the meridian, is δ =-5°. Taking into consideration also the difference in elevation between the observatories, the → declination at which one has equal air mass is moved down to δ =-18°. The extreme limit of observing from Mauna Kea is -60° (10° above horizon) but all programs below -20° are most efficiently carried out from ESO.

Canada, from the St. Lawrence Iroquoian word kanata, meaning "village" or "settlement;" France, from the L. Francia "country of the Franks;" Hawaii, named for Hawai'iloa, a legendary figure from Hawaiian mytholgy; → telescope.

carboxyl radical (COOH)
  رادیکال ِ کربوکسیل   
râdikâl-e karboksil (#)

Fr.: radical carboxyl   

Chem.: The -COOH group, regarded as the essential and characteristic constituent of organic acids.

From carb-, variant of carbo- before a vowel, from → carbon, + ox, from → oxygen, + -yl a suffix used in the names of radicals.

  آبشار، پی‌شار   
âbšâr (#), peyšâr

Fr.: cascade   

1) A waterfall or a succession of small waterfalls.
2) A succession of stages or processes, as in → cascade shower, → cascade error, → cascade transition.

From Fr., from It. cascata "waterfall," from cascare "to fall," from V.L. *casicare, from L. casum, p.p. of cadere "to fall," → case.

Âbšâr, from âb "water," → Aquarius, + šâr "pouring of water and liquids, waterfall;" peyšâr "waterfall succession," from pey "step, succession," as in peyâpey, + šâr. This word maybe related to Skt. sar- "to flow, run, hurry," Gk. iallo "I send out," L. salio "I jump." It may also be variant of Mod.Pers. cal-, calidan "to walk, be going," car-, caridan "to pasture, graze," Av. car- "to come and go," Skt. cari- "to move, walk, wander."

cascade error
  ایرنگ ِ پی‌شاری، ~ آبشاری   
irang-e peyšâri, ~ âbšâri

Fr.: erreur en cascade   

An error that amplifies as the process of calculation goes on.

cascade; → error.

cascade shower
  رگبار ِ پی‌شاری، ~ آبشاری   
ragbâr-e peyšâri, ~ âbšâri

Fr.: gerbe   

Multiple generations of secondary cosmic rays when the primary particles produce a succession of secondaries which have the same effects as the primary.

cascade; → shower.

cascade transition
  گذرش ِ پی‌شاری   
gozareš-e peyšâri

Fr.: transition en cascade   

A photon generation mechanism in an atom in which a transition initiates a series of secondary transitions from lower electronic levels.

cascade; → transition.

chemical adsorption
  برشم ِ شیمیایی   
baršam-e šimiyâyi

Fr.: adsorption chimique   

Same as → chemisorption.

chemical; → adsorption.

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