Fr.: nébuleuse Omega
An → H II region located in the rich star fields of the → Sagittarius area of the Milky Way. Its distance from the Earth is between 5,000 and 6,000 → light-years and spans some 15 light-years in diameter. Its other designations are: Swan Nebula, Messier 17, and NGC 6618.
Omega, Gk. alphabet letter; → nebula.
Fr.: Omicron Ceti
Another name for → Mira.
Omicron, Gk. alphabet letter; Ceti, → Cetus.
Fr.: Omicron (ο) Lupi
A bright star of → apparent visual magnitude V = 4.3 lying in the constellation → Lupus. Among its other designations: HD 130807, HR 5528, HIP 72683. It is an → early-type star of → spectral type B5 IV and a member of the → Scorpius-Centaurus association. Ο Lupi is in fact a → binary system whose components have an angular separation of 0.043 arcsec, corresponding to a physical separation of 5.3 → astronomical units, with a mass ratio of 0.91.
L. omni-, combining form of omnis "all, every," of unknown origin.
Visp-, from Mid.Pers. visp- "all;" O.Pers. visa-, vispa- "all;" Av. vīspa- "all, every, entire, universal" (vīspô.ayāra- "lasting all the days," vīspô.vīδvah- "knowing everything, omniscient"); cf. Skt. vīśva- "all, every; whole, universal."
Having very great or unlimited power or authority.
visp-bâšandé, visp-bâš, visp-bâšâ
Same as → ubiquitous.
visp-dânâ (#), visp-âgâh (#)
Having infinite knowledge, awareness, understanding, or insight.
bar- (#), dar- (#)
Adverb, used as prefix denoting "in, into, onto; toward; with continuous activity," etc.
O.E. on, variant of an "in, on, into," from P.Gmc. (cf. Du. aan, Ger. an, Goth. ana "on, upon"), from PIE base *ano "on" (cf. Av. ana "on," Gk. ana "on, upon," L. an-, O.C.S. na, Lith. nuo "down from").
Bar "on; up; upon; in; into; at; forth; with; near; before;
(Mid.Pers. abar; O.Pers.
upariy "above; over, upon, according to;" Av. upairi "above, over,"
upairi.zəma- "located above the earth;" cf. Gk. hyper- "over, above;"
L. super-; O.H.G. ubir "over;" PIE base *uper "over").
Fr.: en ligne
The state when two or more devices are directly connected and are communicating efficiently.
Fr.: réduction enligne
Preliminary reduction of observational data at a telescope simultaneously with their acquisition.
Fr.: observation sur la source
In comparison with → off-source observation, an observation which is concerned with the source itself.
on-the-spot (OTS) approximation
An approximation in the treatment of photoionized → H II regions, whereby secondary ionizing photons are absorbed immediately very close to their site of emission. The secondary photons, produced by → radiative recombinations directly to the → ground states, are thus ignored with respect to the ionizing photons emitted by the → exciting star. The OTS approximation requires that the ionized gas be sufficiently dense so that secondary ionizing photons are very likely absorbed within the H II region.
1) The smallest whole number, symbol 1; unity.
The → multiplicative identity for real and
O.E. an, from P.Gmc. *ainaz (cf. O.N. einn, Dan. een, O.Fris. an, Du. een, Ger. ein, Goth. ains), PIE base *oinos, cognate with Pers. yek, as below.
Yek "one, alone," from Mid.Pers. êwak, êv, yak, êk; cf. Baluci hivak "one, single" (Proto-Iranian *aiua-ka-); O.Pers. aiva- "one, alone;" Av. aēuua- "one, alone;" Skt. éka- "one, alone, single;" Gk. oios "alone, lonely;" L. unus "one;" E. one.
Fr.: écoulement uni-dimensionnel
A hypothetical flow in which all the flow parameters may be expressed as functions of time and one space coordinate only. This single space coordinate is usually the distance measured along the center-line of some conduit in which the fluid is flowing (B. Massey, Mechanics of Fluids, Taylor & Francis, 2006).
Fr.: magnétohydrodynamique à une fluide
A → magnetohydrodynamics treatment in which the → plasma consists only of one particle species and moves with the bulk speed. The thermal motion of the particles is neglected and thus there is no motion of particles relative to each other.
Fr.: correspondance un à un
A relationship between two distinct sets of elements such that every member of the first set can be paired with a unique element in the second set; and every member of the second set can be paired with a unique element in the first set. Two sets so related are said to be isomorphic.
A plant, Allium cepa, of the amaryllis family, having an edible, succulent, pungent bulb (Dictionary.com).
M.E., from Anglo-French union, O.Fr. oignon "onion," from L. unio-, also "pearl," literally "one, unity;" sense connection is the successive layers of an onion.
Mid.Pers. payâz, payâc; cf. Sogd. piyâk "onion," Yidgha piq, Vakhi piûk, Yazghulami piyeq, Kurd. pivaz; maybe related to PIE *peuk- "to prick, to sting, to stab," because of its pungent taste; cf. Gk. peukos "sting, prick, cusp, peak."
ivâz, tanhâ (#)
An adverb meaning without others or anything further; alone; solely; exclusively. → if and only if.
M.E., from O.E. anlic, from ân, → one.
Ivâz, from Mid.Pers. êvâz/êvâc, from Proto-Iranian
*aiua-ka-; cf. Pers. yek,
1) Classical philosophy: That part of metaphysics which is concerned with
the nature of existence or the essence of things.
From Mod.L. ontologia, from Gk. on (genitive ontos) "being" (pr.p. of einai "to be"), akin to L. esse "to be;" Pers. hastan, astan "to be," hasti "existence, being," as below; + -logia, → -logy.
abr-e Ort (#)
Fr.: nuage de Oort
Named after Jan Hendrik Oort (1900-1992), a Dutch astronomer who proposed its existence in 1950. He also made major contributions to our knowledge of the structure and rotation of the Milky Way Galaxy; → cloud.