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

The value of the exponent in the → initial mass function as derived by Salpeter (1955) for solar to → intermediate mass stars in the Solar neighborhood: &Gamma = 1.35 or &alpha = 2.35, or x = -1.35. Also known as Sapleter index.

→ Salpeter function; → slope.

1) A crystalline compound, sodium chloride, NaCl, occurring as a mineral, used for food seasoning and preservation.
2) Chem.: A solid compound formed when the hydrogen of an acid has been replaced by a metal.

O.E. sealt; cf. O.N., O.Fris., Goth. salt, Du. zout, Ger. Salz from PIE *sal- "salt;" cf. Gk. hals (genitive halos) "salt, sea;" L. sal; O.Ir. salann; Welsh halen; O.C.S. sali "salt."

Namak "salt;" Mid.Pers. namak "salt."

Oceanography: One of several alternating columns of rising and descending water resulting from a → mixing process that occurs when warm salty water overlies a colder and relatively fresher layer of water. If the overlying salty water loses enough heat, it sinks down into the colder, fresher water, lengthening into a finger of salty water. Becuse the finger loses heat faster than it loses salt, the salt finger will continue to sink (salty water is denser than fresh water of the same temperature). Hence the salt finger loses more heat and displaces the colder water around it, which rises up and mixes into the warm salty layer above. Salt fingers are an example of → double-diffusive convection and play an important role in oceanic mixing. See also → fingering instability, → fingering convection.

→ salt; → finger.

A chemical compound, potassium nitrate, KNO₃. It is a naturally occurring mineral source of nitrogen, and is used in the manufacture of fireworks, fluxes, gunpowder, etc.

M.E. sal peter, salpetre, from O.Fr. salpetre, from M.L. sal petrae "salt of rock," from L. sal, → salt + petra "rock, stone."

Šuré, related to šur "salty;" Mid.Pers. šôr "salty," šorag "salt land;" cf. Skt. ksurá- "razor, sharp knife;" Gk. ksuron "razor;" PIE base *kseu- "to rub, whet."

Statistics: A portion of the units of a population. The units are selected based on a randomized process with a known probability of selection. The sample is used to make inferences about the population by examining or measuring the units in the sample. → specimen = nemuné (نمونه).

M.E., from O.Fr. essample, from L. exemplum "a sample," literally "that which is taken out," from eximere "to take out, remove."

Nemunân, from nemun, from nemudan "to show;" Mid.Pers. nimūdan, nimây- "to show," from O.Pers./Av. ni- "down; into," → ni- (PIE), + māy- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure."

Statistics: Each possible outcome in a → sample space.

→ sample; → point.

The number of sampling units which are to be included in the sample. In the case of a multi-stage sample this number refers to the number of units at the final stage in the sampling.

→ sample; → size.

Statistics: A set which consists of all possible outcomes of a random experiment.

→ sample; → space.

The act, process, or technique of selecting a number of cases from all the cases in a particular population.

→ sample + → -ing.

Nemunân-giri, literally "taking sample," from nemunân→ sample + giri verbal noun of gereftan "to take, seize, hold;" Mid.Pers. griftan, gir- "to take, hold, restrain;" O.Pers./Av. grab- "to take, seize," cf. Skt. grah-, grabh- "to seize, take," graha- "seizing, holding, perceiving," M.L.G. grabben "to grab," from P.Gmc. *grab, E. grab "to take or grasp suddenly;" PIE *ghrebh- "to seize."

That part of the difference between the expected value of the sample estimator and the true value of the characteristic which results from the sampling procedure, the estimating procedure, or their combination.

→ sampling; → bias.

That part of the difference between a population value and an estimate thereof, derived from a random sample, which is due to the fact that only a sample of values is observed; as distinct from errors due to imperfect selection, bias in response or estimation, errors of observation and recording, etc.

→ sampling; → error.

Same as → Nyquist-Shannon sampling theorem.

→ sampling; → theorem.

One of the units into which an aggregate is divided for the purpose of sampling, each unit being regarded as individual and indivisible when the selection is made.

→ sampling; → unit.

Hard granular powder, consisting of fine grains of rock or minerals, usually quartz fragments, found on beaches, in deserts, and in soil.

O.E. sand; cf. O.N. sandr, O.Fris. sond, M.Du. sant, Ger. Sand; PIE base *samatha- (cf. Gk. psammos "sand," L. sabulum).

Mâsé "sand," of unknown origin.

Variously colored → sedimentary rock composed mainly of sand-like quartz grains cemented by calcite, clay, or iron oxide. The sand accumulated originally underwater in shallow seas or lakes, or on the ground along shorelines or in desert regions.

→ sand; → stone.

A strong wind carrying sand through the air.

→ sand; → storm.

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.

One of the 5 or 6 → epagomenal days added to the 12 months of 30 days each in the → French Republican Calendar. Sansculottides began on September 17 or 18 and approximately ended on the → autumnal equinox, on September 22 or 23 of the → Gregorian calendar. These days were kept as festivals of Virtue, Genius, Labor, Opinion, and Rewards. There was a sixth Sanculottide, called Revolution, in → leap years.

From Fr. sans-culotte, literally "without knee breeches," a revolutionary of the lower class in the French revolution. The appellation was originally a term of contempt applied by the aristocrats but later was adopted as a popular name by the French revolutionaries. It refers to the fashionable culottes (silk knee breeches) of the aristocrats as distinguished from the working class sans-culottes, who traditionally wore pantalons (long trousers).

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.

The period of 223 → synodic month, equaling 6585.32 days or 18 years, 11.33 days, after which the Sun, Earth, and Moon return to approximately the same relative geometry. When two eclipses are separated by a period of one Saros, they occur at the same node with the Moon at nearly the same distance from Earth and at the same time of year. Thus, the Saros is a useful tool for organizing eclipses into families or series. Each series typically lasts 12 or 13 centuries and contains 70 or more eclipses (F. Espenak, NASA).

Gk. saros, from Akkadian shār, Sumerian shar "multitude, large number." The ancient astronomers knew the Saros cycle, but they did not use the term Saros. In the Almagest, Ptolemy refers to the Saros as the "periodic time" (periodikos chronos) and gives it the following properties: 223 → synodic months = 239 → anomalistic months = 242 → draconistic months = 6,585 ¹/₃ days = 241 revolutions in longitude plus 10 ²/₃ degrees. Edmund Halley seems to have been the first to apply this term to an eclipse cycle, in 1691.