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old stellar population
porineš-e setâre-yi-ye kohan
Fr.: population stellaire vielle
A population of stars in a stellar system that have definitely left the → main sequence.
A silicate mineral of magnesium (Mg2SiO4) and iron (Fe2SiO4,) found commonly in basalt and in carbonaceous chondrites.
From Ger. Olivin, from olive, because of its olive-green to gray-green color, + -in equivalent to -ine a noun suffix used in chemical and mineralogical nomenclature.
Fr.: Olympus Mons
The highest peak on Mars, and the largest volcano in the solar system. It rises to a height of 27 kilometres above the datum level selected on the basis of atmospheric pressure.This gigantic shield volcano, 700 kilometres across, is similar in nature to volcanoes on Earth but its volume is at least fifty times greater than its nearest terrestrial equivalent.
From L. Mons, → mountain, + Olympus, from Gk. Olympos a mountain (2966 m) in north-east Greece, on the boundary between Thessaly and Macedonia, mythical abode of the greater Grecian gods.
Omega Centauri (ω Cen)
Fr.: Omega centauri
The largest and most luminous → globular cluster associated with the Milky Way Galaxy. Omega Centauri is located about 18,300 → light-years away and contains several million old stars. The stars in its center are so crowded that they are believed to be only 0.1 light-year away from each other. It is about 12 billion years old. Omega Centauri was first listed in Ptolemy's catalog nearly two thousand years ago. In 1677 Edmond Halley reported it as a nebula, and in the 1830s John Herschel was the first to correctly identify it as a globular cluster. Also called NGC 5139.
Omega, Gk. alphabet letter; Centauri, → Centaurus.
Fr.: effet ω
Omega (ω), Gk. letter of alphabet; → effect.
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.