Fr.: dispesrion anormale
The phenomenon whereby the → refractive index of light in a medium changes rapidly with wavelength in the vicinity of an → absorption band. Hence the → dispersion curve of the substance shows marked deviations from → Cauchy's equation, in contrast with the behavior of → normal dispersion. On the shorter λ side of the absorption band the refractive index falls off more rapidly than required by Cauchy's equation representing values of n for visible light. On the long λ side of the absorption band the index is very high, decreasing at first rapidly and then more slowly as one goes beyond the absorption band.
anomalous luminosity effect
oskar-e tâbandegi-ye nâsân
Fr.: effet luminosité anormale
Discrepant luminosity classes derived for the same → Am star when different criteria are used. Lore specifically, a luminosity criterion may indicate a → giant star, wheras another criterion indicates a → supergiant.
Fr.: décalage anormal vers le rouge
The high redshift of a quasar which is seemingly physically associated with a galaxy of low redshift.
anomalous X-ray pulsar (AXP)
pulsâr-e pertwâ-ye iks-e nâsân
Fr.: pulsar X anormal
A member of a small class of → X-ray pulsars with long rotation periods (6-12 seconds), short → spin-down times (~ 103-105 years), and → soft X-ray spectrum. AXPs show no evidence of being → X-ray binary systems. Their magnetic fields, as deduced from their spin-down rate, are the highest known, reaching 1013-1015 → gauss. AXPs are generally believed to be → magnetars.
anomalous Zeeman effect
oskar-e Zeeman-e nâsân
Fr.: effet Zeeman anormal
The splitting of a spectral line into several components in the → Zeeman effect when the magnetic field is weak. The splitting is much more complex than in the normal effect. The number of components of the lines often considerably exceeds their number in the normal effect. Contrarily to the normal Zeeman effect, the anomalous effect cannot be explained by classical theory. The historically "anomalous" effect is accounted for by the inclusion of electron spin in the total angular moment. In fact the idea of electron spin was put forward (Uhlenbeck and Goudsmit, 1926) to explain the anomalous Zeeman effect.
In general, a deviation from the norm.
Anomaly from → anomalous
Nâsâni, from nâ- negation suffix + sân "rule, law, custom" + -i noun maker suffix.
Having an unknown or unacknowledged name. → anonymous object.
L. annymus, from Gk. annumos "nameless," from → an- "without" + onoma, onuma "name". Compare with L. nomen, Skt. nama, Av. nama, Mod. Pers. nâm, PIE *nomen "name".
Anâm, from Persian → a-, an- "without" + nâm "name," as above. Binâm, from bi- "without" + nâm.
barâxt-e anâm, ~ binâm
Fr.: objet anonyme
An → astronomical object which has not been catalogued.
L. ansa "handle."
Dastak "handle," from dast "hand" (Mid.Pers. dast; O.Pers. dasta-; Av. zasta-; cf. Skt. hásta-; Gk. kheir; L. praesto "at hand;" Arm. jern "hand;" Lith. pa-žastis "arm-pit;" PIE *ghes-to-) + -ak suffix denoting relation, affinity, similarity.
In physics and mathematics an a priori assumption that is used to establish the form of an equation or a system of equations. The ansatz, which is verified later by the result, is meant to facilitate the solution. → Bethe ansatz.
From Ger. Ansatz "attempt, approach, beginning."
The direction in the sky (in → Columba) away from which the Sun seems to be moving (at a speed of 19.4 km/s) relative to general field stars in the Galaxy.
Daštargân, Jonubgân (#)
The south polar area, south of latitude 66° 33' 8'' S.
Daštargân, from daštar, → south, +
-gân suffix indicating the direction.
Antares (α Scorpii)
Antares, in Gk. "rival of Mars," from Gk. → anti + Ares "the Gk. god of War, called Mars by the Romans". The comparison with the planet Mars is because they are both red in color and have the same brightness.
Každom-del "the heart of the Scorpion," from každom "scorpion + del "heart." Qalb-ol-'Aqrab "the heart of the Scorpion," from Ar. Qalb "heart + 'aqrab "scorpion".
M.E., from from L. antecedentem, from antecedere "go before, precede," from ante- "before" + cedere "to yield, to go," → process.
1) General: A device or a set of wires that receives or sends out
L. antenna "sail yard," the long yard that sticks up on some sails, of unknown origin, perhaps from PIE base *temp- "to stretch, extend." In this sense, it is a translation of Gk. keraiai "horns" (of insects).
Âten, from Fr. antenne, from L. as above.
Fr.: gain d'antenne
A measure of the directivity of a radio telescope. It is the ratio of the amount of power received in the direction the dish is pointing to the smaller amount of power from other directions in the sidelobes.
Fr.: lobe d'antenne
A three-dimensional section of the → radiation pattern ofa directional antenna, bounded by one or more cones of nulls or by regions of diminished irradiance.
Fr.: diagramme de rayonnement
The response of an antenna to incident radiation as a function of the direction of incidence of the radiation. A generic antenna pattern consists of a → main lobe and a number of smaller → side lobes. Also called → radiation pattern.
Fr.: température d'antenne
In radio astronomy, a measure of the power absorbed by the antenna. In an ideal, loss-free radio telescope, the antenna temperature is equal to the brightness temperature if the intensity of the received radiation is constant within the main lobe. → antenna; → temperature.
antenna; → temperature.
Fr.: galaxies des Antennes
The pair of colliding galaxies NGC4038 and NGC4039 and the long arcing insect-like "antennae" of luminous matter revealed by optical telescopes. The "antennae" are believed to have been produced by the collision between the galaxies that began about 100 million years ago and is still occurring. The Antennae Galaxies, about 60 million → light-years from Earth, lie in the constellation → Corvus.
Kahkešânhâ, plural of kahkešân→ galaxy; šâxak "insect antenna," from šâx "horn" (Mid.Pers šâk, cf. Skt. sakha- "a branch, a limb," Arm. cax, Lit. šaka, O.S. soxa, PIE *kakhâ "branch") + -ak suffix denoting relation, affinity, similarity (as in dastak, pos(tak, pas(mak, xarak, nâxonak, mus(ak, eynak);