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

A large cloud of faint stars extending eastward from the → Small Magellanic Cloud to the → Large Magellanic Cloud. The wing is in fact the tail of a much larger → neutral hydrogen structure linking the SMC to the LMC. Models and observations suggest that the structure known as the → Magellanic Stream results from the Clouds' interaction with each other and the Milky Way. Several works support the finding that the SMC wing is pointing toward the LMC, and is therefore closer to us than the SMC bar.

Named after the American astronomer Harlow Shapley (1885-1972), who discovered this structure (1940, Harvard Bull., 914, 8); → wing.

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.

→ linear astrolabe.

Named after the Iranian mathematician and astronomer Sharafeddin Tusi (c1135-1213), who invented the instrument. Not to be confused with Nasireddin Tusi (1201-1274), → Nasireddin couple; → staff.

1a) The full or proper portion or part allotted or belonging to or contributed or owed by an individual or group.
1b) One of the equal fractional parts into which the capital stock of a joint-stock company or a corporation is divided.
2a) To divide and distribute in shares; apportion.
2b) To use, participate in, enjoy, receive, etc., jointly (Dictionary.com).

M.E., from O.E. scearu "a cutting, shearing; a part or division," related to sceran "to cut;" O.H.G. scara "troop, share of forced labor," Ger. Schar "troop, band," properly "a part of an army," O.N. skör "rim;" from PIE root *(s)ker- "to cut."

Bâš, from Kurd. (Sorani) baš "share, part;" variant of baxš "share, portion;" baxšidan "to divide," → division; bâž "tribute, toll, impost," → distribute.

1) Having a thin cutting edge or a fine point.
2) Of an image, clearly defined; distinct. → sharp image.

M.E.; O.E. scearp "cutting, keen, sharp;" cf. Du. scherp, Ger. scharf "sharp;" PIE base *(s)ker- "to cut."

Tiz "sharp," variants tež, tej, tij, tiq, tik, tig; Mid.Pers. tigr, têz, têž "sharp;" O.Pers. tigra- "pointed," tigra.xauda- "pointed helmet (epithet of Scythians);" Av. tiγra- "pointed," tiγray- "arrow," tiži.arštay- "with the pointed spear;" cf. Skt. tikta- "sharp, pungent, bitter," tejas- "sharpness, edge, point or top of a flame;" PIE base *st(e)ig- "to stick; pointed." Cognates in other IE languages: Gk. stizein "to prick, puncture," stigma "mark made by a pointed instrument;" L. in-stigare "to goad;" O.H.G. stehhan; Ger. stechen "to stab, prick;" Du. stecken; O.E. sticca "rod, twig, spoon;" E. stick.

An image with clear and distinct details. Opposite of → blurred image.

→ sharp; → image.

1) To make sharp or sharper.
2) To increase the spatial resolution or the clearness of an image; same as → deblur; → deconvolve.

Verbal form of → sharp.

Tigidan "to sharpen," verbal form of tig→ sharp.

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 second brightest star in the constellation → Scorpius, lying at a distance of 570 → light-years. With → Lesath (Upsilon Scorpii) both stars make up the Scorpion's stinger. Shaula is a → multiple star with three visible → components. The first one, Lambda Scorpii A, is classified as a B2 IV → subgiant. The 15th magnitude Lambda Scorpii B has a separation of 42 arcseconds from component A, while the 12th magnitude Lambda Scorpii C is 95 arcseconds from A. It is not known whether or not these components are physically associated with component A. The component A is actually a → triple system consisting of two → B-type stars and a → pre-main sequence star.

Shaula, from Ar. ash-shaulah (الشولاء) the "raised tail" of Scorpion.

Same as → supra-horizontal branch star.

→ supra-; → horizontal; → branch; → star.

1) (n.) General: A scissors of large size.
Physics: A → stress applied to a body in the plane of its faces or perpendicular to its axis. As a consequence, parallel planes in the body remain parallel, but are displaced in a direction parallel to themselves. See also → strain.
2) (v.) General: To cut hair, fleece, or foliage from the surface of something using a sharp tool.
Physics: To cause something to deform or break by applying forces acting parallel to the plane.

M.E. sheren, O.E. sceran, scieran; cf. O.H.G. scrinden "to split;", Du. scheren, Ger. scheren "to shear;" from PIE *(s)ker- "to cut, to scrape, to hack;" cf. Pers. kârd "knife;" Av. kart- "to cut;" Skt. krntáti "cuts;" Gk. keirein "to cut, shear;" Lith. skiriu "to separate."

1) Karn, from Laki caré, Farâhâni carra, Tabari carci "a scissors for cutting sheep wool," cognate with Pers. kârd "knife; " Mid.Pers. kârt "knife," karēnītan, karītan "to cut;" Av. karət- "to cut;" cf. Skt. kart- "to cut," krpāna- "sword, knife;" Gk. karpos "fruit;" L. carpere "to cut, divide, pluck;" PIE base *(s)ker- "to cut."
Karnidan infinitive from karn.

The ratio of the applied → stress to the change in shape (→ strain) produced in an → elastic body. The bigger this quantity the more rigid is the material since for the same change in strain a bigger force is needed. Also called → shear modulus.

→ shear; → modulus.

A type of → instability occurring within a → fluid as a result of the → shear caused by → differential rotation. The condition for shear instability is expressed by the → Richardson criterion. Shear turbulence is likely the most efficient → mixing process in stellar → radiative zones.

→ shear; → turbulence.

A wave that occurs in an elastic medium with the disturbances perpendicular to the direction of motion of the wave. Shear waves do not propagate through a fluid. Also called S-wave, secondary wave, and transverse wave.

→ shear; → wave.

The brightest star in the constellation → Cassiopeia. It is a supergiant K0 III star with a visual magnitude of 2.23 at a distance of 230 light-years. It has a large luminosity, 855 times that of our Sun, and a notable size, 48 times that of the Sun. Its effective temperature is 4530 K. Name variants: Schedar, Shedar, and Schedir. Also known as HR 168 and HD 3712.

From Ar. as-sadr (الصدر) "chest, breast," contraction of as-sadr-al-Zat-al-kursi (الصدر‌الذات‌الکرسی) "the chest of the throne's owner" or "the chest of the seated one" referring to the Ar. rendering of the character in Gk. mythology.

A domesticated ruminant mammal with a thick woolly coat and (typically only in the male) curving horns. It is kept in flocks for its wool or meat (OxfordDictionaries.com).

M.E., from O.E. sceap; related to O.Frisian skep, O.Saxon scap, O.H.G. scaf, Ger. Schaf.

Gusfand, guspand, from Mid.Pers. gôspand "cattle in general," especially "sheep, goats," as distinguished from horses and cows, Av. gaospənta- "sanctified, consecrated cow," from gao-, → cow, + spənta- "sanctfied, holy," → holiday.

1) General: A relatively thin external form covering a hollow space.
2) The hard exterior of an egg; a hard outer covering of an animal, such as a mollusk.
3) Physics: → electron shell.
4) → seashell.
5) Astro.: → shell burning; → shell galaxy; → shell star; → shellular rotation; → SNR shell.

M.E.; from O.E. scell, sciell; cognate with Dutch schil "peel, skin," O.Norse skel "shell," from PIE root *(s)ker "to cut," → bark.

Pusté "shell," from pust "skin;" Mid.Pers. pôst "skin;" O.Pers. pavastā- "thin clay envelope used to protect unbaked clay tablets;" Av. pastô-, in pastô.fraθanhəm "of the breadth of the skin;" Skt. pavásta- "cover," Proto-Indo-Iranian *pauastā- "cloth."
Pukel, from (Nahâvand, Hamadân, Ilâm) pukel "egg shell," (Kurd.) tukel, probably (prefixed) from PIE root *(s)ker- "to cut," → bark, → scalp.

The nuclear reactions in a shell around a star's core that continue after the fuel in the core itself has been exhausted. As the fuel is progressively exhausted, the shell moves outward until it enters regions too cool for the reactions to continue. For example, after the exhaustion of hydrogen in the core, helium burning might take place in the core with a shell of hydrogen burning surrounding it. Stars may have more than one region of shell burning during their stellar evolution, each shell with its own nuclear reactions. → hydrogen shell burning; → helium shell burning.

→ shell; → burning.

An elliptical galaxy that is surrounded by thin shells of stars which are thought to have been ejected during a galaxy merger. Shell galaxies are different from ring galaxies in that the shells are much further away from the galaxy's centre and much fainter than the rings. Spectroscopy of the stars in the shell show that they are old whereas the stars in a ring galaxy are young.

→ shell; → galaxy.

A main-sequence star, usually of spectral class B to F, whose spectrum shows bright emission lines superimposed on the normal absorption lines. The emission spectrum is explained by the presence of a circumstellar shell of gas surrounding the star at the equator. Shell stars are fast rotators.

→ shell; → star.