Fr.: test du lithium
The presence or not of the lithium absorption line at 6708 Å, which is considered to be a sufficient condition for → substellarity in → L dwarfs. It has been shown that any object with lithium absorption and → effective temperature less than 2670 K is a → brown dwarf. For a discussion of potential problems with the lithium test see Kirkpatrick et al. (1993, ApJ 406, 701).
A prefix meaning "stone," used in the formation of compound words.
From Gk. lithos "stone."
Lito-, loan from Gk., as above.
bonpâr-e sangdust, ~ litodust
Fr.: élément lithophile
In the → Goldschmidt classification, a → chemical element that shows an → affinity for → silicate phases and is concentrated in the silicate portion of the Earth (→ crust and → mantle). This group includes → lithium (Li), → beryllium (Be), → sodium (Na), → magnesium (Mg), → potassium (K), → calcium (Ca), → barium (Ba), → titanium (Ti), → chromium (Cr), → aluminium (Al), → silicon (Si), → phosphorus (P), → chlorine (Cl), etc.
sangsepehr (#), litosepehr
The solid portion of the → Earth, as compared to the → atmosphere and the → hydrosphere. The lithosphere consists of semi-rigid plates that move relative to each other on the underlying → asthenosphere. The process is known as → plate tectonics and helps explain → continental drift.
haft xâharân (#), camce-ye kucak (#)
Little, from M.E., O.E. lytel, from W.Gmc. *lutila- (cf. Du. luttel, O.H.G. luzzil, Ger. lützel, Goth. leitils), from PIE *leud- "small;" dipper, from dip, O.E. dyppan "immerse," from P.Gmc. *dupjanan.
Haft xâharân "the seven sisters," from haft "seven"
(Mid.Pers. haft; Av. hapta; cf. Skt. sapta; Gk. hepta;
L. septem; P.Gmc. *sebun; Du. zeven; O.H.G. sibun;
Ger. sieben; E. seven; PIE *septm)
+ xâharân plural of xâhar "sister;" Mid.Pers. xwâhar
"sister;" Av. xvanhar- "sister;" cf. Skt. svásar- "sister;"
Sogdian xwār; Gk. eor; L. soror (Fr. soeur);
O.C.S., Rus. sestra; Lith. sesuo; O.Ir. siur; Welsh chwaer;
M.Du. suster; Du. zuster; O.H.G. swester;
Goth. swistar; Ger. Schwester;
Swed. sister; Dan. søster;
O.E. sweostor, swuster; E. sister.
Little Ice Age
asr-e yax-e kucek
Fr.: petit âge glaciaire
A roughly 400-year period from the mid-16th through the mid-19th centuries when temperatures over much of Europe were unusually cold. Glaciers in the Alps advanced and European rivers froze much more often than during the past century. Harvests failed, livestock perished, and poor people suffered from famine and disease. The Little Ice Age coincided with two successive low → solar activity periods, the → Sporer minimum and the → Maunder minimum.
Fr.: prisme de Littrow
A prism having angles of 30, 60, and 90°, which uses the same face for input and dispersed radiation. The beam is reflected at the face opposite to the 60° angle because it is coated to be highly reflecting. A beam entering at the → Brewster angle undergoes minimum deviation and hence maximum dispersion. Littrow prisms are used in laser cavities to fine tune lasers by selection of wavelength.
Joseph Johann Littrow (1781-1840), Austrian astronomer; → prism.
âyene-ye Lloyd (#)
Fr.: miroir de Lloyd
An optical arrangement in which light from a source is allowed to fall on a plane mirror at → grazing incidence. The light directly coming from the source interferes with the light reflected from the mirror forming an → interference pattern. See also → Fresnel's biprism, → Fresnel's mirrors.
After the Irish physicist Humphry Lloyd (1800-1881); → mirror.
1) bâr; 2) bâr kardan (#)
Fr.: 1) charge; 2) charger
1) Something that is borne or carried.
From M.E. lode, originally the same word as lode, from O.E. lāad "way, course, carrying;" cf. O.N. leith "way, route," O.H.G. leita "procession."
Bâr kardan "to load," composite verb from bâr "load, charhe, burden," (Mid.Pers. bâr, from O.Pers./Av. base bar- "to bear, carry;" Mod.Pers. bordan "to carry;" L. brutus "heavy, dull, stupid, brutish;" Skt. bhara- "burden, load," bharati "he carries;" Gk. baros "weight;" Mod.Pers. gerân "heavy;" Skt. guru; L. gravis; PIE *gwere- "heavy," *bher- "carry, give birth") + kardan "to do, to make" (Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build;" Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base kwer- "to do, to make").
Verbal noun of → load.
Fr.: escarpe lobée
A surface feature on a planet or satellite in the form of a line of cliffs. Lobate scarps are formed when planetary or lunar mantle cools down and contracts inside. The loss of volume squeezes portions of the outer crust together. Eventually, the crust breaks and some of it is pushed up, creating long cliffs that look like wrinkles. Lunar scarps are generally tens of kilometers long and less than 100 m high. They have formed during the last billion years.
General: A roundish projection that is part of a larger structure.
From M.L. lobus, from L.L. lobus "hull, husk, pod," from Gk. lobos "lobe of the ear, vegetable pod," probably related to leberis "husk of fruits;" from PIE base *lep- "to peel, flay."
Lap "lobe," variants lâp, lâb "piece, big piece, big cut," lappé "split pea; any of the two parts of a timber split through the length," maybe cognate with Gk. lobos, as above. Alternatively, related to Pers. las "loose," PIE *leu- "to loosen, divide, cut apart" (cf. Gk. lyein "to loosen, untie, slacken," lysus "a loosening;" L. luere "to loose, release;" → analysis).
Fr.: fonction de lobe
The configuration of the response lobes of a radiotelescope.
kuasâr-e lap ciré
Fr.: quasar à lobes dominants
A → radio-loud quasar in which the lobes dominate the whole emission. It has been conjectured that this phenomenon is an → orientation effect. If the → jet is close to the plane of the sky, the lobes will dominate. See also → core-dominated quasar.
Pertaining to, characteristic of, or restricted to a particular place or particular places.
From O.Fr. local, from L.L. localis "pertaining to a place," from L. locus "place."
Mahali, related to mahal "place, locality," from Ar.
Fr.: bras local
tangol-e mahali, hobâb-e ~
Fr.: Bulle locale
A region of low density in the → interstellar medium surrounding the → Solar System. It extends at least 300 → light-years in most directions and encompasses the stars of the immediate → solar neighborhood. The Local Bubble contains a hot, million-degree ionized hydrogen gas that emits in → X-rays. → Neutral hydrogen has a density approximately one tenth of the average for the interstellar medium in the Milky Way. The bubble is thought to be a result of the → shock waves from → supernovae sweeping through the region within the past two to four million years.
goruh-e mahali (#)
Fr.: Groupe local
A small → galaxy cluster of about 50 galaxies to which our → Milky Way galaxy belongs. The Local Group occupies a volume of space nearly 10 million → light-years across centered somewhere between the → Andromeda Galaxy (M31) and the Milky Way, which are the dominant galaxies of the group; Andromeda being the principal member. Both of these galaxies exhibit spiral structures, and each is attended by a large family of satellite → dwarf galaxies. The Local Group also includes a third spiral galaxy known as → Triangulum (M33), which is bound to Andromeda. The remaining members span a range of → Hubble classification types from dwarf spheroidal to Irr to Sb and Sc and cover a factor of 10 in → metallicity. The total mass of the Local Group is estimated to be about 2 × 1012 solar masses, although this value is still uncertain to within a factor of about 2. The velocities of the individual galaxies of the Local Group are not particularly high. Therefore no member is believed to be able to escape the group, which is thus considered to be gravitationally → bound. Another remarkable member of the Group is → IC 10.
local inertial frame
cârcub-e laxtnâk-e mahali, ~ laxtimand-e ~
Fr.: référentiel inertiel local
A coordinate system or frame of reference defined in the vicinity of the Earth in which Newton's first law of motion is valid; that is, a non-rotating and non-accelerating reference frame.