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

An elementary particle created in high-energy particle collisions having a short life and a strangeness quantum number of 1. For example, sigma and xi baryons are strange particles. A strange particle is produced when a strange quark is created in a high-energy collision. → strangeness.

→ strange; the concept of "strange" arose from the observation that these particles decay rapidly, in contrast to others that do not. → particle.

A quantum number used to describe certain short-lived particles. It is defined as the number of strange anti-quarks minus the number of strange quarks in a particle. Strangeness is conserved in any strong and electromagnetic interaction, but not in weak interactions.

Strangeness, the quality or condition of being → strange.

A data center dedicated to the collection and worldwide distribution of astronomical data and related information. It is located at the Strasbourg Astronomical Observatory, France. The CDS has several goals, mainly: collecting all of the useful information regarding astronomical objects in computerized form, including observational data produced by observatories on the ground or in space; upgrading these data by critical evaluations and comparisons; and distributing the results to the astronomical community. Currently the CDS services include: → SIMBAD, Aladin interactive sky atlas, and VizieR catalogues.

CDS, short for Centre de Données astronomiques de Strasbourg.

A layered structure of sedimentary rocks in which the individual layers can be traced a considerable distance. The layers can be caused by many differences which include materials of different composition, color, grain size or orientation.

Strati-, from → stratum + -fication from L. -ficare "to do, make."

Ciné, → stratum + bandi, from bastan "to bind, shut; to contract, get, acquire; to coagulate," (Mid.Pers. bastan/vastan "to bind, shut," Av./O.Pers. band- "to bind, fetter," banda- "band, tie," Skt. bandh- "to bind, tie, fasten," PIE *bhendh- "to bind," cf. Ger. binden, E. bind, → band).

Of, relating to, or determined by → stratigraphy.

→ stratum; → -graphic.

The study of → sedimentary rock units, including their geographic extent, age, classification, characteristics and formation.

→ stratum; → -graphy; → -logy.

The second major layer of Earth's atmosphere, just above the → troposphere and below the → mesosphere, extending from about 20 km to 90 km above the Earth. It is characterized by little vertical increase in temperature.

From Fr. stratosphère, literally "sphere of layers," coined by Fr. meteorologist Léon-Philippe Teisserenc de Bort (1855-1913) from L. stratus "a spreading out" (from p.p. stem of sternere "to spread out") + -sphère (→ sphere), as in atmosphère.

Cine-sepehr, from Ciné, → stratum, + sepehr, → sphere.

Of, relating to, or characteristic of the stratosphere.

→ stratosphere; → -ic.

A partnership of NASA and the German Aerospace Center, consisting of an extensively modified Boeing 747SP aircraft carrying a reflecting telescope with an effective diameter of 2.5 m. NASA Ames Research Center manages SOFIA's science and mission operations in cooperation with the Universities Space Research Association and the German SOFIA Institute. SOFIA is the largest airborne observatory in the world, with a planned 20-year lifetime.

→ stratospheric; → observatory; → infrared; → astronomy.

Geophysics: A layer of the atmosphere or the sea, regarded as lying between horizontal planes.
Geology: A single bed of → sedimentary rock, generally consisting of one kind of matter representing continuous deposition.

From L. stratum "thing spread out, pavement," from neuter p.p. of sternere "to spread out, lay down, stretch out," from PIE base *ster- "to spread, extend, stretch out;" cf. Pers. gostar-, gostardan "to spread;" Av. star- "to spread," starati "spreads;" Skt. star- "to spread out, extend, strew," strnati "spreads;" Gk. stornumi "I spread out," strotos "spread, laid out;" Ger. Strahlung "radiation," from strahlen "to radiate," from Strahl "ray;" from M.H.G. strāle; from O.H.G. strāla "arrow,stripe."

Ciné "layer," from cin present stem of cidan "to collect, gather;" Mid.Pers. cyn- "to gather, collect," Parthian Mid.Pers. (+*ni-) ncyn- "to pile up, heap up together," nycnyšn "stack;" Av. ci- (caē-, caii-) "to heap up, gather;" cf. Skt. ci- "to gather, heap up," cinoti "gathers."

1) A long, narrow mark, smear, band of color, or the like.
2) Mineralogy: The color that minerals leave behind when scratched against a black or white porcelain plate. It is used to identify the mineral.

From M.E. streke, from O.E. strica; akin to O.H.G. strich "line."

Xaš "streak, scratch, stria," maybe from xarâš-, xarâšidan "to scratch;" Proto-Ir. *xrāš- "to scratch" (Cheung 2007), or a variant of xatt, → line.

In → fluid mechanics, the curve defined by the positions of all particles which have passed through a given point. In laboratory experiments, streak line may be displayed by the stream of color resulting from injection of a dye into the flow.

→ streak; → line.

1) (n.) A general term for any river, brook, rivulet or course of running water.
A steady flow of a fluid, small solid particles, or radiant energy. → Magellanic stream. Related concepts: → current (jarayân = جریان); → flow (tacân = تچان).
2) (v.) To move or proceed continuously like a flowing stream.

O.E. stream "a course of water;" cf. O.S. strom, O.N. straumr, Dan. strøm, Swed. ström, Norw. straum, Du. stroom, O.H.G. stroum, Ger. Strom "current, river," from PIE base *sreu- "to flow;" cf. Pers. rud, from Mid.Pers. rôd "river;" O.Pers. rautah- "river;" Skt. srotas- "river," sru- "to flow;" Pali sota- "stream, flood;" Gk. rhoos "a stream, a flowing," from rhein "to flow."

1) Râbé, from dialectal Gilaki râbé "flowing of water or liquid," Semnâni rové "a stream of water flowing beyond control," Pers. colloquial râ (in râ gereftan "to overflow, flow beyond control"); probably from PIE base *rei- "to flow;" cf. Skt. ray- "to flow, run," raya- "stream;" L. rivus "stream, brook;" O.C.S. reka "river;" M.Ir. rian "river, way;" Goth. rinnan "run, flow," rinno "brook;" M.L.G. ride "brook;" O.E. riþ "stream."
2) Râbidan infinitive of râbé.

Hydrology: A steady current in a stream or river.
Oceanography: A deep, narrow, well-defined fast-moving ocean current.

→ stream; → current.

A → stream tube with a small cross section so that the variation of velocity over it is negligible.

→ stream; → filament.

A pipe-shaped volume obtained by drawing → streamlines through every point of a closed curve in the fluid. Since the stream tube is bounded on all sides by streamlines and since, by definition, there can be no velocity across a streamline, no fluid may enter or leave a stream tube, except through its ends. See also → stream filament.

→ stream; → tube.

Any long, narrow piece or thing, as a spray of a plant or a strip of cloud; something that streams. → coronal streamer; → helmet streamer

M.E. stremer, from → stream + -er.

Derafšak, from derafš "flag, banner;" Mid.Pers. drafš "banner;" Av. drafša- "banner;" cf. Skt. drapsá- "flag, banner; drop, spark;" also Fr. drapeau; It. drappo "flag;" Lith. drapana "dress."

1) Fluid mechanics: Any process or instance of flowing.
2) Computer science: A condition of a terminal or modem that has locked into a constant carrier signal, thus preventing the normal flow of data.

Verbal noun of → stream.

An imaginary continuous curve drawn in a fluid so that the tangent at every point of it at any instant of time coincides with the direction of the motion of the fluid at that point. The component of velocity at right angles to the streamline is always zero. If a number of streamlines is considered at a particular instant, the pattern they form gives a good indication of the flow then occurring. Same as → flow line. See also → path line, → stream tube.

→ stream; → line.

The ratio of the peak intensity of the central core of the image of a point source to the corresponding intensity contained in an image obtained in the absence of aberration. An optically perfect system has a Strehl ratio of unity. The ratio may be computed by integrating the area under a → modulation transfer function (MTF) curve and dividing it by the integral over the diffraction-limited MTF.

In honor of Karl Strehl (1864-1940), the German physicist and mathematician who introduced the concept; → ratio.