An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 458
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.

Leo
  شیر   
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 resembling a lion. Its brightest star, α Leonis or → Regulus, is of the first magnitude. Abbreviation: Leo; Genitive: Leonis.

L. Leo, from Gk. leon, from a non-I.E. language, perhaps Semitic (cf. Heb. labi "lion," pl. lebaim; Egyptian labai, lawai "lioness").

Mid.Pers. šagr "lion;" cf. Parth. šarg; Sogd. šarγu "lion."

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).

Leo.

Leonids
  شیریان   
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.

leptokurtic
  بلند-افراشته   
boland-afrâšté

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
  لپتون   
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.

Lepus
  خرگوش   
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.

letter
  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.

level
  تراز   
tarâz (#)

Fr.: niveau   

A position with respect to a given or specified base. → energy level.

From O.Fr. livel, from L. libella "a balance, level," diminutive of libra "balance, scale."

Tarâz "level; a level," from tarâzu "balance, scales," Mid.Pers. tarâzên-, taraênidan "to weigh," Proto-Iranian *tarāz-, from *tarā- "balance, scale" ( cf. Skt. tulā- "scales, balance, weight," from tul- "to weigh, make equal in weight, equal," tolayati "weighs, balances," L. tollere "to raise," Gk. talanton "balance, weight," Atlas "the Bearer" of Heaven," Lith. tiltas "bridge;" PIE base telə- "to lift, weigh") + Av. az- "to convey, conduct, drive," azaiti drives" (cf. Skt. aj- "to dive, sling," ájati "drives," ajirá- "agile, quick," Gk. agein "to lead, guide, drive, carry off," L. agere "to do, set in motion, drive," from PIE root *ag- "to drive, move," → act).

level of significance
  تراز ِ نشاناری   
tarâz-e nešânâri

Fr.: niveau de significativité   

Same as → significance level.

level; → significance.

lever
  اهرم   
ahrom (#)

Fr.: levier   

A rigid bar that pivots about a point and is used to move or lift a load at one end by applying force to the other end. → lever arm.

M.E. levere, levour; O.Fr. levier "a lifter, a lever," agent noun from lever "to raise," from L. levare "to raise," from levis "light" in weight.

Ahrom, of unknown etymology.

lever arm
  بازوی ِ اهرم   
bâzu-ye ahrom (#)

Fr.: bras de levier   

The distance between the point of application of a → force and the → axis around which the object could → rotate.

lever; → arm.

levitation
  بالاشد   
bâlâšod

Fr.: lévitation   

A physical process occurring in stellar atmospheres whereby → radiation pressure selectively pushes certain elements outward, leading to an atmospheric overabundance of such elements.

from levitate modeled on gravitate, from L. levitas "lightness," from levis "light."

Bâlâšod, literally "raising up," from bâlâ "hig, up," → high + šod past stem of šodan "to go, to pass, to become," → set.

levo-, lev-
  چپ-   
cap- (#)

Fr.: levo-   

A combining form meaning "left" and "counterclockwise," used in the formation of compound words, such as → levorotation, levocardia, levoglucose, etc. The variant lev- occurs before vowels. Compare → dextro-.

From L. laevo-, from laevus, cf. Gk. laios, Russ. levyj, + epenthetic vowel -o-.

Cap-, from cap "left," of unknown etymology.

levorotation
  چپ‌چرخش   
capcarxeš

Fr.: lévorotation   

The counterclockwise rotation of the → plane of polarization of light (as observed when looking straight through the incoming light) by certain substances.

Adj. related to → levorotation.

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