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

Deviating from the normal or common order, form, or rule. → anomaly.

From Gk. anomalos "uneven, irregular," from → an- "not" + homalos "even," from homos "same".

Nâsân, from Pers. nâ- "not" + sân "rule, custom, law, fashion," literally "out of rule".

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; → dispersion.

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.

→ anomalous; → luminosity; → effect.

The high redshift of a quasar which is seemingly physically associated with a galaxy of low redshift.

→ anomalous; → redshift.

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; → X-ray; → pulsar.

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.

→ anomalous; → Zeeman effect.