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

An adjective suffix meaning "without."

M.E. -les, from O.E. -leas, from leas "free (from), devoid (of), false;" cf. Du. -loos, Ger. -los "-less," , O.N. lauss "loose, free, vacant," M.Du. los, Ger. los "loose, free," Goth. laus "empty, vain."

Bi- privative prefix, → a-.

A diminutive, noun-forming suffix (booklet; platelet).

M.E., from M.Fr. -elet, from L. -ellus + M.Fr. -et, from L. -ittus, both diminutive suffixes.

-Cé diminutive suffix, from Mid.Pers. -cak, variants -êžak (as in kanicak "little girl," sangcak "small stone," xôkcak "small pig"), also Mod.Pers. -ak.

Resembling or similar to. → spacelike, → timelike; → solar-like star.

A suffixal use of like " of the same form, appearance," in the formation of adjectives, from M.E. lic, lik, shortening of O.E. gelic "like, similar;" cf. O.S. gilik, Du. gelijk, Ger. gleich "equally, like."

-sân suffix of similarity, from sân "way, manner."
-vâr a suffix meaning "resembling, like," from Mid.Pers. -wâr; Av. -vara, -var; cf. Skt. -vara.
-mânand, suffix from mânand, → similar.

A combining form used in the names of sciences or bodies of knowledge, such as → biology, → geology, → cosmology. See also → -ics.

M.E. -logie, from O.Fr. -logie, from L. -logia, from Gk. -logia, from legein "to speak, tell over; to choose, gather," logos "word, speech, thought, account."

-Šenâsi, from šenâs, present stem of šenâsidan, šenâxtan "to know, discern, distinguish, be acquainted with;" Mid.Pers. šnâxtan, šnâs- "to know, recognize," dânistan "to know;" O.Pers./Av. xšnā- "to know, learn, come to know, recognize;" cf. Skt. jñā- "to recognize, know," jānāti "he knows;" Gk. gignoskein "to know, think, judge;" L. gnoscere, noscere "to come to know" (Fr. connaître; Sp. conocer); P.Gmc. *knoeanan; O.E. cnawan; E. know; Rus. znat "to know;" PIE base *gno- "to know."

1) A suffix forming adverbs from adjectives.
2) An adjective suffix meaning "-like."

M.E. -li, -lich(e); O.E. -lic; cf. O.Fris. -lik, Du. -lijk, O.H.G. -lih, Ger. -lich, O.N. -ligr.

1) -âné suffix of adverbs, from Mid.Pers. -ânag.
2) -vâr denoting "resembling, like," from Mid.Pers. -wâr, Av. -vara, -var; cf. Skt. -vara.

A type of → brown dwarf with an → effective temperature ranging from about 2200 K to about 1300 K, corresponding to luminosities about 4 x 10^-4 to 3 x 10^-5 times that of the Sun. L dwarfs are intermediate in temperature between M and → T dwarfs. Their spectra in the optical show weak titanium oxide (TiO) and vanadium oxide (VO) absorption lines and strong metallic hydrides CrH (8611 and 9969 Å) and FeH (8692 and 9896 Å). Also are present strong neutral atomic lines of alkali metals Na I (8183, 8195 Å), K I (7665, 7699 Å), Rb I (7800, 7948 Å), Cs I (8521, 8943 Å), and sometimes Li I (6708 Å). The prototype of the L-dwarf class is → GD 165B. The spectral classification was first defined by Kirkpatrick et al. 1999, ApJ 519, 802 and Martin et al. 1999, AJ 118, 2466.

For the reasoning behind the choice of the letter L, see Kirkpatrick et al. 1993, ApJ 406, 701; → dwarf.

A → semiregular variable with a period of 141 days. It has a → spectral type of M5 III corresponding to an → effective temperature of ~ 3500 K. It has a radial velocity relative to the → Local Standard of Rest of 33.3 km s^-1. At a distance of 64 → parsecs, L₂ Pup is the second nearest → asymptotic giant branch (AGB) star next to R Doradus; it is ~ 30% closer than → Mira. Recent → near-infrared JHKL band observations by Kervella et al. (2014, 2015) show a compact dust disk around the central star, with an inner rim of 6 → astronomical units and an outer edge of 13 au, at an inclination of approximately 82°. The → circumstellar environment of L₂ Pup was observed with → ALMA. The → molecular emission shows a → differentially rotating disk, inclined to a nearly edge-on position (Homan et al., 2017, A&A 601, A5 and references therein).

Star name in the → Bayer designation scheme; → Puppis.

La Niña. A condition in which a significant decrease (more than 0.5 °C from average water temperatures) occurs in sea surface temperature (cold event) in the central and eastern equatorial Pacific. La Niña has a natural 3-6 year cycle and can persist for 1-3 years. It is the counterpart to the → El Nino (warm event), and its spatial and temporal evolution in the equatorial Pacific is, to a considerable extent, the mirror image of El Niño, although La Niña events tend to be somewhat less regular in their behavior and duration.

American Sp. La Niña "the girl," to distinguish it from → El Nino.

The site of the → European Southern Observatory's first observatory in Chile, inaugurated in 1969. It is located 160 km north of the town of La Serena and 600 km north of Santiago at an altitude of 2,400 m bordering the southern extremity of the Atacama Desert. La Silla is equipped with several optical telescopes with mirror diameters of up to 3.6 m. The 3.5 m New Technology Telescope was the first in the world to have a computer-controlled main mirror, a technology developed at ESO. The ESO 3.6 m telescope is now home to the world's largest extrasolar planet hunter: HARPS (High Accuracy Radial velocity Planet Searcher), a spectrograph with unrivalled precision.

From Sp. la silla "the saddle," after the apparent shape of the mountain on which the observatory is situated. Originally known as Cinchado.

A building or place equipped for carrying out scientific research, experimentation, investigation, observation, etc.

M.L. laboratorium "a place for labor or work," from L. laboratus, p.p. of laborare "to work."

Âzmâyešgâh, from âzmâyeš, → experiment, + -gâh "place, time," → university.

The Lizard. A small constellation in the northern hemisphere, at about 22h right ascension, 45° north declination. Its brightest star is only of magnitude +3.8, and the constellation contains no other star above fourth magnitude. Its most famous object is BL Lacerta, the prototype → BL Lac objects. Abbreviation: Lac; genitive: Lacertae.

From L. lacertus (fem. lacerta) "lizard," of unknown origin.

Calpâsé "lizard," variants karpâsa, karisa, kelpasa; cf. Skt. krakacapad- "saw-footed, a lizard, chameleon," from krakaca- "saw" + pad "foot" (Pers. pâ).

1a) Deficiency or absence of something needed, desirable, or customary.
1b) Something missing or needed. See also → default, → deficiency, → shortage.
2a) (v.tr.) To be without or deficient in; to fall short in respect of.
2b) (v.intr.) to be absent or missing, as something needed or desirable (Dictionary.com).

M.E. lak; cognate with M.L.G. lak, M.Du. lac "deficiency;" akin to O.Norse lakr "deficient."

Nast, from negation prefix na- "in-, non," → not, + ast, hast "is," from astan, hastan "to be," → exist.

Absent; wanting; deficient.

→ lack; → -ing.

1) A piece of equipment consisting of a series of bars or steps between two upright lengths of wood, metal, or rope, used for climbing up or down something.
2) A series of ascending stages by which someone or something may progress (OxfordDictionaries.com).

M.E. laddre, O.E. hlæder "ladder, steps" (cognates: M.Du. ledere, O.H.G. leitara, Ger. Leiter), from PIE root *klei- "to lean," → incline.

Nardebân "ladder."

1a) A lagging or falling behind; retardation.
1b) Mechanics: The amount of retardation of some motion.
1c) Electricity: The retardation of one alternating quantity, as current, with respect to another related alternating quantity, as voltage.
2) To fail to maintain a desired pace or to keep up; fall or stay behind (Dictionary.com).

Possibly from Scandinavian; cf. Norwegian lagga "to go slowly."

Lek, from lek lek kardan "to walk slowly, to lag behind."

1) A body of seawater that is almost completely cut off from the ocean by a barrier beach.
2) The body of seawater that is enclosed by an atoll.

Lagoon, from Fr. lagune, from It. laguna "pond, lake," from L. lacuna "pond, hole," from lacus "pond;" → nebula.

Mordâb "lagoon," literally "dead water," from mord, mordé "dead" + âb "water."
The first element from mordan, mir- "to die," marg "death," mard "man;" Mid.Pers. murdan "to die;" O.Pers. marta- "dead," martiya- "man;" Av. mərəta- "died, dead," amərətāt- "immortality;" cf. Skt. mar- "to die," mriyáe "dies;" Gk. emorten "to die," ambrotos "immortal;" L. morior "to die" (Fr. mourir), mors, mortis "death" (Fr. mort), immortalis "immortal;" Lith. mirtis "mortal;" O.C.S. mrutvu "dead;" O.Ir. marb; Welsh marw "died;" O.E. morþ "murder;" PIE base *mor-/*mr- "to die."
The second element âb "water," from Mid.Pers. âb "water;" O. Pers. ap- "water;" Av. ap- "water;" cf. Skt. áp- "water;" Hitt. happa- "water;" PIE āp-, ab- "water, river;" cf. Gk. Apidanos, proper noun, a river in Thessalia; L. amnis "stream, river" (from *abnis); O.Ir. ab "river," O.Prus. ape "stream," Lith. upé "stream;" Latv. upe "brook."

A giant → H II region lying in the direction of → Sagittarius about 5,000 → light-years away. It represents a giant cloud of interstellar matter which is currently undergoing star formation, and has already formed a considerable cluster of young stars (NGC 6530).

→ lagoon; → nebula.

A set of second order → differential equations for a system of particles which relate the kinetic energy of the system to the → generalized coordinates, the generalized forces, and the time. If the motion of a → holonomic system is described by the generalized coordinates q₁, q₂, ..., q_n and the → generalized velocities  q^.₁, q^.₂, ..., q^._n, the equations of the motion are of the form: d/dt (∂T/∂q^._i) - ∂T/∂q^._i = Q_i (i = 1, 2, ..., n), where T is the kinetic energy of the system and Q_i the generalized force.

→ Lagrangian; → equation.

1) Of or relating to Joseph-Louis Lagrange (1736-1813), see below.
2) Same as → Lagrangian function. The Lagrangian of a → dynamical system describes its → dynamics and when subjected to an → action gives rise to → field equations and a → conservation law for the theory. Lagrangians are the keys for the mathematical formulation of field theories ( → field theory).
See also:
→ inner Lagrangian point, → Lagrangian density, → Lagrangian dynamics, → Lagrangian formalism, → Lagrangian function, → Lagrangian method, → Lagrangian multiplier, → Lagrangian particle, → Lagrangian point.

After the French/Italian mathematician Joseph-Louis Lagrange (1736-1813), who was the creator of the → calculus of variations (at the age of nineteen). He made also great advances in the treatment of → differential equations and applied his mathematical techniques to problems of → mechanics, especially those arising in astronomy.

A quantity, denoted L_d, describing a continuous system in the → Lagrangian formalism, and defined as the → Lagrangian per unit volume. It is related to the Lagrangian L by:
L = ∫∫∫L_d d³V.
Lagrangian density is often called Lagrangian when there is no ambiguity.

→ Lagrangian; → density.