An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -le Lag lam Lap Lar lat law Led Len lev lig lik lin lin lin lis Loc loc log Lor low lum lun Lut Lyr > >>

Number of Results: 482
Lense-Thirring effect
  اسکر ِ لنزه-تیرینگ   
oskar-e Lense-Thirring

Fr.: effet Lense-Thirring   

An effect predicted by → general relativity whereby a rotating body alters the → space-time around it. This effect can be thought of as a kind of "dragging of inertial frames," as first named by Einstein himself. A massive spinning object pulls nearby objects out of position compared to predictions for a non-rotating object. The effect is important for rapidly rotating → neutron stars and → black holes, but that near Earth is extraordinarily small: 39 milli-arc second per year, about the width of a human hair seen from 400 meters away.

Named after Austrian physicists Joseph Lense (1890-1985) and Hans Thirring (1888-1976), who first discovered this phenomenon in 1918; → effect.

  ۱) لنزش؛ ۲) لنزنده   
1) (n.) lenzeš; 2) (adj.) lenzandé

Fr.: 1) effet de lentille; 2) amplificateur   

1) The act or effect produced by a lens, in particular a → gravitational lens.
2) Pertaining to the object that produces the lensing effect. → lensing galaxy.

From → lens + → -ing.

1) Lenzeš, verbal noun of lenzidan, verb formed from E. lens + -idan infinitive suffix.
2) Lenzandé, verbal adj. from lenzidan, as above.

lensing effect
  ا ُسکر ِ لنزش   
oskar-e lenzeš

Fr.: effet de lentille   

Effect created by a → gravitational lens.

lensing; → effect.

lensing galaxy
  کهکشان ِ لنزنده   
kahkeâân-e lenzandé

Fr.: galaxie amplificatrice   

A galaxy that acts as a → gravitational lens. The effect can also be due to a cluster of galaxies.

lensing; → galaxy.

lensing object
  بر‌آخت ِ لنزنده   
barâxt-e lenzandé

Fr.: objet amplificateur   

An astronomical object that creates → gravitational lensing. See also → lensing galaxy.

lensing; → object.

lensing potential
  توند ِ لنزش   
tavand-e lenzeš

Fr.: potentiel de l'effet de lentille gravitationnelle   

An important quantity in the characterization of → gravitational lensing. The lensing potential is obtained by projecting the three-dimensional Newtonian potential on the lens plane and by properly re-scaling it. It is a two-dimensional analog to the → gravitational potential.

lensing; → potential.


Fr.: lenticule   

Circular and elliptical features on the surface of → Europa with diameters ranging from 10 to 100 km. Many are domes that seem to have been pushed up from below. These domes might have been formed by warm water rising between the cold ices of the outer crust, in a scenario recalling the → magma chambers on Earth.

From L. lenticula "freckle," diminutive of lens (genitive lentis) "lentil," → lens.

Kakmak "freckle."

lenticular galaxy
  کهکشان ِ عدسی‌وار   
kahkešân-e adasvâr (#)

Fr.: galaxie lenticulaire   

A lens-shaped galaxy, which is an enormous grouping of old stars with very little internal structure.

Lenticular "resembling a lentil in form," → lens; → galaxy.

Lenz's law
  قانون ِ لنتز   
qânun-e Lenz (#)

Fr.: loi de Lenz   

The direction of an induced current is such as to oppose the cause producing it. The cause of the current may be the motion of a conductor in a magnetic field, or it may be the change of flux through a stationary circuit.

Named after Heinrich Friedrich Emil Lenz (1804-1865), German physicist, who published the law in 1834; → law.

Šir (#)

Fr.: Lion   

The Lion. One of the most conspicuous → constellations in the northern hemisphere, at 10h 30m → right ascension, 15° north → declination. Leo is a constellation of the → Zodiac crossed by the Sun from August 10th to September 16th. Leo is visible from February through June. Its brightest star, α Leonis or → Regulus, is of the first magnitude. Abbreviation: Leo; Genitive: Leonis. The neighboring constellations are → Cancer, → Coma Berenices, → Crater, → Hydra, → Leo Minor, → Lynx, → Sextans, → Ursa Major, and → Virgo. Leo contains many bright stars, many of which were individually identified by the ancients. There are four stars of first or second magnitude, which render this constellation especially prominent. Apart from Regulus, the constellation is home to the bright stars → Denebola, the nearby star Wolf 359, and to a number of famous deep sky objects, among them galaxies Messier 65, Messier 66, Messier 95, Messier 96, Messier 105, and NGC 3628. There are two → meteor showers associated with the constellation. The → Leonids usually peak on November 17-18 every year and have a → radiant near the bright star Gamma Leonis. The January Leonids are a minor shower that peaks between January 1 and 7. Leo has 11 stars with known planets.


Leo Minor
  شیر ِ کوچک   
Šir-e Kucak (#)

Fr.: Petit Lion   

The Lesser Lion. A faint constellation in the northern hemisphere, at 10h 20m right ascension, 35° north declination. Abbreviation: LMi; genitive: Leonis Minoris.

Leo; Minor, from L. minor "lesser, smaller, junior," from PIE base *min- "small."

Šir, → Leo; kucak "small," (Mid.Pers. kucak "small"), related to kutâh "short, small, little," kudak "child, infant," kutulé, → dwarf, Mid.Pers. kôtâh "low," kôtak "small, young; baby;" Av. kutaka- "little, small."

Leo P
  شیر P   
Šir P

Fr.: Lion P   

A → dwarf galaxy recently discovered near the Milky Way in → neutral hydrogen → 21-centimeter line observations. Optical imaging observations indicate that it is located between 1.5 and 2.0 Mpc from the Milky Way. This places Leo P in the → Local Volume but beyond the → Local Group. The dwarf galaxy has extreme properties: it is the lowest-mass system known that contains significant amounts of gas and is currently forming stars (Katherine L. Rhode et al. 2013, AJ 145, 149).


Širiyân (#)

Fr.: Léonides   

A → meteor shower emanating from an apparent point in the constellation → Leo that occurs from November 14-20, with a maximum on November 17-18. It is due to the annual passage of the Earth through the orbit of the comet → Tempel-Tuttle and encounter with the dust debris from the comet.

From L. Leon, → Leo, + → -ids.


Fr.: leptocurtique   

A frequency distribution with a positive → kurtosis, that has a more elevated peak around the mean than the corresponding normal distribution. → platykurtic.

From Gk. lepto-, combining form of leptos "thin, slight" + → kurtosis.

Boland-afrâšté "highly-elevated," from boland "high, tall, elevated, sublime" (variants bâlâ "up, above, high, elevated, height," borz "height, magnitude" (it occurs also in the name of the mountain chain Alborz), Laki dialect berg "hill, mountain;" Mid.Pers. buland "high;" O.Pers. baršan- "height;" Av. barəz- "high, mount," barezan- "height;" cf. Skt. bhrant- "high;" L. fortis "strong" (Fr. and E. force); O.E. burg, burh "castle, fortified place," from P.Gmc. *burgs "fortress;" Ger. Burg "castle," Goth. baurgs "city," E. burg, borough, Fr. bourgeois, bourgeoisie, faubourg; PIE base *bhergh- "high") + afrâšté "raised, elevated, erect," p.p. of afrâštan, → kurtosis.

lepton (#)

Fr.: lepton   

An → elementary particle that does not participate in the → strong interaction. The Lepton family includes → electrons, → muons, tau leptons, → neutrinos and their → antiparticles. The lepton is a → fermion.

From Gk, lepto-, combining form of leptos "small, slight" + -on a suffix used in the names of subatomic particles (gluon; meson; neutron), quanta (photon; graviton), and other minimal entities or components.

lepton degeneracy
  واگنی ِ لپتون   
vâgeni-ye lepton

Fr.: dégénérescence des leptons   

Postulate that the magnitude of the lepton number density is comparable to or larger than the thermal radiation photon number density, so relaxation to equilibrium produces a degenerate sea of neutrinos. Degenerate neutrinos would suppress the number of neutrons relative to protons in the very early Universe; degenerate antineutrinos would suppress the number of protons relative to neutrons. Either case would affect BBNS (Peebles, P. et al., 2009, Finding the Big Bang, Cambridge: UK, Cambridge Univ. Press).

lepton; → degeneracy.

lepton era
  دوران ِ لپتونی   
dowrân-e leptoni (#)

Fr.: ère leptonique   

The era following the hadronic era, when the Universe consisted mainly of leptons and photons. It began when the temperature dropped below 1012 degrees kelvin some 10-4 seconds after the Big Bang, and it lasted until the temperature fell below 1010 degrees kelvin, at an era of about 1 second.

lepton; → era.

lepton number
  عدد ِ لپتونی   
adad-e leptoni (#)

Fr.: nombre leptonique   

In particle physics, a quantum number attributed to elementary particles which is conserved in nuclear reactions. It is +1 for a lepton, -1 for an antilepton and 0 for other particles.

lepton; → number.

Xarguš (#)

Fr.: Lièvre   

The Hare. A small → constellation in the southern hemisphere at about 6h right ascension, 20° south declination. Abbreviation: Lep; genitive: Leporis.

L. lepus "hare."

Xarguš "rabbit, hare," literally "ass-ear," Mid.Pers. xargôš, from xar "donkey, ass" (Mid.Pers. xar "donkey;" Av. xara- "donkey;" cf. Skt. khára- "donkey, mule") + guš, → ear.

  ۱) وات؛ ۲) نامه   
1) vât (#); 2) nâmé (#)

Fr.: lettre   

1) A symbol or character representing a sound of which words are formed used in writing and printing a language.
2) A written or printed communication addressed to a person or organization.

M.E., from O.Fr. letre "character, letter; missive," from L. littera "letter of the alphabet," litterae (plural) "epistle, literature"

1) Vât "letter, word," from vat- "to speak, say;" cf. (Kurd.) wittin "to speak, say," → article, (Nâyin) vâte, (Qohrud) vâta, (Sangesar) -vât-/vân, (Zazaki) vâtiš, (Awromani) wâtay/wâc-, (Farizand) -vât/-vaj, (Gaz) vâ-/vât, related to Pers. vâžé "word;" Mid.Pers. vâc, vâcak "word, speech;" âva "voice, sound," âvâz "voice, sound, song," bâng "voice, sound, clamour" (Mid.Pers. vâng); Av. vacah- "word," vaocanghê "to decalre" (by means of speech), from vac- "to speak, say;" cf. Skt. vakti "speaks, says," vacas- "word;" Gk. epos "word;" L. vox "voice;" PIE base *wek- "to speak."
2) Nâmé, → book.

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