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

A → square matrix that is not a → singular matrix.

→ non-; → singular; → matrix.

See also → non-thermal.

→ non-; → thermal.

Same as → suprathermal escape.

→ non-; → thermal; → escape.

Fluid mechanics: Having no → viscosity. Same as → inviscid.

From → non- + → viscous.

The time of day when the Sun crosses the observer's meridian and is at its highest point above the horizon. At this point, the Sun lies due south of an observer in the northern hemisphere and due north of an observer in the southern hemisphere.

M.E. none; O.E. non, from L. nona hora "ninth hour" of daylight by Roman reckoning, about 3 p.m.

Nimruz, from nim "mid-, half" (Mid.Pers. nêm, nêmag "half;" Av. naēma- "half;" cf. Sk. néma- "half") + ruz→ day.

The dispersion in which a shorter wavelength is associated with a higher → refractive index. Contrasted with the → anomalous dispersion.

→ normal; → dispersion.

A theoretical frequency distribution for a set of variable data, usually represented by a bell-shaped curve with a mean at the center of the curve and tail widths proportional to the standard deviation of the data about the mean. Same as → Gaussian distribution.

→ normal; → distribution.

1) A mathematical technique for adjusting a series of values (typically representing a set of measurements) according to some transformation function in order to make them comparable with some specific point of reference.
2) Process of introducing a numerical factor into an equation so that the area under the corresponding graph (if finite) shall be made equal to unity.
3) To change in scale so that the sum of squares or the integral of squares of the transformed quantity is zero.

Verbal noun of → normalize.

Representation of numbers, quantities, or other entities by symbols; a system of symbols for such a purpose.

From L. notationem (nom. notatio) "a marking, explanation," from notatus, p.p. of notare "to note."

Namâdgân, from namâd, → symbol, + -gân suffix denoting order, organization, multiplicity.

A general understanding; vague or imperfect conception or idea of something.

From L. notio "concept, conception, idea," from noscere "to know," → knowledge.

Pendâré, noun from pendâštan "to imagine, consider, think," → imaginary number.

→ nuclear burning.

→ nuclear; → combustion.

Apparent cross-section possessed by an atomic nucleus when it undergoes a particular type of collision process.

→ nuclear; → cross section.

A → nuclear reaction in which a heavy atomic nucleus splits into two or more approximately equal parts, usually as the result of the capture of a slow, or → thermal neutron by the nucleus. It is normally accompanied by the emission of further neutrons or → gamma rays and very large amounts of energy. The neutrons can continue the process as a → chain reaction, so that it becomes the source of energy in a → nuclear reactor or an atomic bomb. It may also be a trigger for → nuclear fusion in a hydrogen bomb. Fission occurs spontaneously in nuclei of uranium-235, the main fuel used in nuclear reactors.

→ nuclear; → fission.

A → nuclear reaction between atomic nuclei as a result of which a heavier → atomic nucleus is formed, a small fraction of mass is lost, and a large quantity of energy is released. Nuclear fusion is the source of the energy of stars.

→ nuclear; → fusion.

An analysis technique applied to some atomic nuclei that have the property to behave as small magnets and respond to the application of a magnetic field by absorbing or emitting electromagnetic radiation. When nuclei which have a magnetic moment (such as ¹H, ¹³C, ²⁹Si, or ³¹P) are submitted to a constant magnetic field and at the same time to a radio-frequency alternating magnetic field, the nuclear magnetic moment is excited to higher energy states if the alternating field has the specific resonance frequency. This technique is especially used in spectroscopic studies of molecular structure and in particular provides valuable information in medicine that can be used to deduce the structure of organic compounds.

→ nuclear; → magnetic; → resonance.

A process in which the energy, composition, or structure of an atomic nucleus changes.

→ nuclear; → reaction.

A change in the → energy level or state of an atomic → nucleus involving a → quantum of energy.

→ nuclear; → transition.

The changing of atoms of one element into those of another by suitable nuclear reactions.

→ nuclear; → transmutation.

A constituent of the atomic nucleus, i.e. a proton or a neutron.

From nucle(us), → nucleus, + -on a suffix used in the names of subatomic particles, probably extracted from → ion.

Haston, from hast(é)→ nucleus + -on, as above.

The practical applications of nuclear physics, and the techniques associated with those applications.

From → nucleon + → -ics.