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

An alternative cosmology, initially conceived by Hannes Alfvén in the 1960s, that attempts to explain the development of the visible Universe through the interaction of electromagnetic forces on astrophysical plasma. Like the steady state model, plasma cosmology hypothesizes an evolving Universe without beginning or end.

→ plasma; → cosmology.

A system of logic with more than two → truth values, as opposed to → classical logic. A polyvalent logic may have a continuous scale of values with → true and → false as limiting → extremes.

→ polyvalent; → logic.

The generic term for systems of → formal logic like → first-order logic and → second-order logic. Predicate logic contains → variables which can be quantified (→ quantify, → quantification).

→ predicate; → logic.

A branch of logic that deals with the → truth values of logical statements (→ sentences, → propositions) and uses → logical connectives to build more complex → expressions. The distinctive feature of propositional logic is that it does not deal with logical relationships and properties that involve the parts of a statement smaller than the simple statements making it up. The propositions are evaluated as → true or → false. A more expressive system is provided by the → first-order logic.

→ proposition; → -al; → logic.

The study and use of radiation and radioactive substances for the treatment of diseases.

→ radio; + → -logy.

A catalog of → H II regions in the → southern  → Milky Way based on observations obtained at Mount Stromlo Observatory (Australia). It contains 181 → H-alpha emission objects characterized by their positions, dimensions, and estimated brightness.

Rodgers,A.W., Campbell, C.T., Whiteoak, J.B., 1960, MNRAS, 121, 103; → catalog.

A branch of physics dealing with the way matter flows and deforms.

From rheo- "flow, current, stream," from Gk. rheos "stream," cognate with Pers. rud "river," → Eridanus, + → -logy.

Ravâné, from ravân "flowing, running," pr.p. of raftan "to go, walk; to flow;" (Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack") + šenâsi, → -logy.

Ross, Frank E., 1926, "New proper-motion stars, (second list)", Astronomical Journal 36, 856.

Frank Elmore Ross (1874-1960) was the succeeded to E. E. Barnard at Yerkes Observatory. He inheriting Barnard's collection of photographic plates. Ross decided to repeat the same series of images and compare the results with a → blink comparator. He discovered 379 new variable stars and over 1000 stars of high proper motion.

A deep → objective prism survey of the → Large Magellanic Cloud carried out with the Curtis Schmidt telescope on Cerro Tololo in Chile. A total of 1272 stars, generally brighter than → photographic magnitude ~ 14, are listed in the catalog as proven or probable LMC members. The stars are identified on the charts in the LMC Atlas of Hodge & Wright (1967).

By Nicholas Sanduleak (1933-1990), American astronomer, published in 1970 as Contribution No. 89 of the Cerro Tololo Inter-American Observatory; → catalog.

A general whole-sky catalog compiled by the Smithsonian Astrophysical Observatory which results from the combination of several earlier catalogs. The compilation gives positions and proper motions for 258,997 stars, of which 8,712 are double and 499 variable, with an average distribution of 6 stars per square degree. The star positions have an average standard deviation of 0''.2 at their original epochs (0''.5 at epoch 1963.5). The equinox is 1950.0 and the system that of the FK4.

SAO acrynome of the Smithsonian Astrophysical Observatory; → star; → catalog.

An n extension of → first-order logic that quantifies not only → variables that range over → individuals, but also quantifies over → relations.

→ second; → order; → predicate; → logic.

The branch of geophysics that is concerned with the study of earthquakes and measurement of the mechanical properties of the Earth.

→ seismo-; → -logy.

Same as → propositional logic.

→ sentential; → logic.

A catalog of 1,249 galaxies, brighter than the 13th magnitude, published in 1932. A revised version was published by A.R. Sandage and G. A. Tammann in 1981.

By the American astronomer Harlow Shapley (1885-1972) and the American woman astronomer Adelaide Ames (1900-1932), who died in a drowning accident; → catalog.

A list of 313 individual → H II regions in the → northern → Milky Way (north of declination -27°). It includes several → planetary nebulae, → supernova remnants, and → reflection nebulae. The first edition (Sh-1) was published in 1953 with 142 objects and second and final version (Sh-2) was published in 1959. The catalog categorizes the H II regions in terms of several parameters, such as diameter, form (circular, elliptical, irregular), structure (amorphous/filamentary), brightness, and number of associated stars, which are further discussed in terms of their spectral classes.

Stewart Sharpless (1959) A Catalogue of H II Regions, ApJ Suppl. 4, 257; → catalog.

The science or study of the origin, development, organization, and functioning of human society; the science of the fundamental laws of social relations, institutions, etc. (Dictionary.com).

→ society; → -logy.

A member of a class of unevolved or slightly evolved → Population I disk stars with an → effective temperature, degree of evolution, → metallicity, and kinematic property not very different from those of the Sun. See also → solar-like star; → solar twin.

→ solar; → analogue.

The systematic application of science, technology, and engineering to the exploration and utilization of outer space.

→ space; → technology.

The conventional → Big Bang model, which is based on two assumptions: the → cosmological principle of homogeneity and isotropy leading to the → Robertson-Walker metric, and → Einstein's field equations of general relativity along with familiar properties of matter. This model is a remarkably successful operating hypothesis describing the evolution of the Universe from 1/100 second after the initial event through to the present day. It provides explanations for several basic problems such as: → Hubble's law of recession of galaxies, interpreted in terms of the expansion of the Universe; the abundances of the → light elements, in excellent agreement with the predictions of → primordial nucleosynthesis; and the thermal spectrum and angular isotropy of the → cosmic microwave background (CMB) radiation, as expected from a hot, dense early phase of expansion. For a non-standard model, see → ekpyrotic Universe.

→ standard; → cosmology.

A listing of stars usually ordered by right ascension with observational data elements such as coordinates, magnitude, distance, proper motion, and so on.

→ star; → catalog.