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

A rotation mode in which internal rotation of a star depends essentially on depth and little on latitude: Ω(r,θ) = Ω(r), where r is the mean distance to the stellar center of the considered level surface (or → isobar). This particular mode was introduced by J.-P. Zahn (1992, A&A 265, 115) to simplify the treatment of rotational → mixing, but also on more physical grounds. Indeed differential rotation tends to be smoothed out in latitude through → shear turbulence. See also → von Zeipel theorem; → meridional circulation .

Shellular, the structure of this term is not clear; it may be a combination of → shell (referring to star's assumed division in differentially rotating concentric shells) + (circ)ular, → circular. The first bibliographic occurrence of shellular is seemingly in Ghosal & Spiegel (1991, On the Thermonuclear Convection: I. Shellular Instability, Geophys. Astrophys. Fluid Dyn. 61, 161). However, surprisingly the term appears only in the title, and nowhere in the body of the article; → rotation.

Carxeš, → rotation; puste-yi, adj. of pusté, → shell.

A person who takes care of sheep; a pastor. → shepherd moon.

From M.E. shepherde; O.E. sceaphierde, from sceap "sheep" + hierde "herder," from heord "a herd;" cf. M.L.G., M.Du. schaphirde, M.H.G. schafhirte, Ger. dial. schafhirt.

Cupân "shepherd," variants šobân, šabân; Mid.Pers. šubân, from šu + -bân. The first component from Av. pasu-, fšu- "sheep;" Mid.Pers. pâh, pasvīk "cattle;" Laki and Tâti pas "sheep;" Kurd. pez/paz; Ossetain (Digor.) fus, (Iron.) fys; Zazaki pes "small cattle;" Lâri pah; Qasrâni cu; Sogd. psw "cattle, sheep;" cf. Skt. paśu- "cattle;" L. pecu "flock, farm animals, cattle," pecunia "money, property;" Goth. faihu "money, fortune;" O.E. feoh "cattle, money;" Ger. Vieh "cattle;" Lith. pekus "cattle;" PIE base *peku- "cattle." The second component -pân/-bân a suffix denoting "keeper, guard," sometimes forming agent nouns or indicating relation, → host.

A → natural satellite in orbit near the edge of a → planetary ring, whose → gravitational force on the ring particles strongly controls the distribution of material within the ring, creating ringlets and density waves within the ring and sharp edges at ring boundaries. Examples include → Saturn's → Prometheus and → Pandora, which shepherd the narrow outer → F ring and the → Uranus satellites → Cordelia and → Ophelia and the epsilon ring. The faster-moving inside satellite accelerates the inner ring particles as it passes them, causing them to spiral out to larger orbits. At the same time the slower-moving outer satellite decelerates the outer ring particles as they pass by, causing them to spiral inward. The result is a narrow, well-defined ring.

→ shepherd; → moon.

1) A broad piece of armor carried on the arm as a defense against swords, arrows, etc.
2) A person or thing that protects or defends. → heat shield; → ozone shield; → self-shielding; → shielding effect.

M.E. shelde, from O.E. scield, scild, related to sciell "seashell, eggshell;" cf. Du. schild, Ger. Schild, Goth. skildus; PIE base *(s)kel- "to cut."

Separ "shield," from Mid.Pers. spar "shield;" cf. Skt. phalaka- "board, lath, leaf, shield," phálati "(he) splits;" Gk. aspalon "skin, hide," spolas "flayed skin," sphalassein "to cleave, to disrupt;" O.H.G. spaltan "to split;" Goth. spilda "board;" PIE base *(s)p(h)el- "to split, to break off."

The decrease in attraction between an electron and the nucleus in any atom with more than one → electron shell. The repulsion forces from other electrons in shells cause the net force on electrons in outer shells to be significantly smaller in magnitude. Also known as → screening effect.

→ shield; → effect;

A change in place or position, in particular a change in wavelength, causing a movement of a spectral band or line. → redshift; → blueshift.

Shift, M.E., from O.E. sciftan "to divide, arrange"; akin to O.N. skipa "to arrange, assign."

Kib "shift" from kibidan "to shift, displace, turn on one side," kibidé "displaced, turned on one side."

→ tibia.

→ tibia

Doroštney, literally "big reed," from dorošt, → macro-, + ney "reed, cane."

1) To emit rays of light.
2) Brightness caused by the emission of light.

M.E. s(c)hinen (v.); O.E. scinan "shed light, be radiant;" cf. M.H.G. schinen, O.H.G. skinan; Du. schijnen; Ger. scheinen; Gothic skeinan "to shine, appear;" PIE base *skai- "bright;" cf. Mod.Pers. sâyé "shadow;" Mid.Pers. sâyak "shadow;" Av. a-saya- "throwing no shadow;" Skt. chāya- "shadow;" Gk. skia "shade;" Rus. sijat' "to shine."

Tâbidan, tâb, → radiate; foruq, → gegenschein.

A sharp change in the properties of a gas (density, pressure, temperature).

Shock "sudden blow," from M.Fr. choc "violent attack," from O.Fr. choquer "to strike against, clash;" cf. Du. schokken "to shake, jolt, jerk."

Toš, from Tabari toš "violent blow," batoštən "to strike suddenly," Kurd. tuš "collision," maybe related to Pers. tuš "strength, vigor;" Av. təviši- "strength," tavah- "power;" O.Pers. tauman- "power, strength," tunuvant- "powerful," from tav- "to have power, to be strong, to be able" (related to tavân "power, strength," tavânestan "to be powerful, able;" variants tâv, tâb "power"); cf. Skt. tu- "to be strong, to have authority," tavas-, tavisa- "strong, energetic," tavisi- "power, strength."
Šok, loan from Fr., as above.

A burst of very bright → ultraviolet or → soft X-ray radiation expected to occur in → core-collapse supernovae at the instant when the → supernova shock breaks out of the stellar surface. During the collapse of the progenitor → massive star, the density in the iron core increases drastically. Once the core material reaches → nuclear density, the core rebounds generating a → shock wave that moves outward through the star. When the shock reaches the outermost layers, it ejects them out into space at → relativistic speeds.

→ shock; breakout "a forceful escape from being confined or restrained," from break, from M.E. breken, O.E. brecan (cf. Du. breken, O.H.G. brehhan, Ger. brechen), from PIE base *bhreg- "to break" (see also → fraction) + → out.

Borunzani "emergence, evasion," from borun, → out, + zani verbal noun of zadan "to strike, beat," from Mid.Pers. zatan, žatan; O.Pers./Av. jan-, gan- "to strike, hit, smite, kill" (jantar- "smiter"); cf. Skt. han- "to strike, beat" (hantar- "smiter, killer"); Gk. theinein "to strike;" L. fendere "to strike, push;" Gmc. *gundjo "war, battle;" PIE *g^when- "to strike, kill."

Any of a series of rings/disks that are formed in a jet flow exhausting a → nozzle when there is a huge difference between the exit pressure and the ambient pressure. At sea level, the exhaust pressure might be lower than the thick atmosphere. In contrast, at very high altitudes, the exhaust pressure might be higher than the thin atmosphere. Shock diamonds can appear just as a rocket is taking off, or at high altitudes when it shifts into → supersonic speed. Shock diamonds are also known as Mach diamonds, → Mach disks, Mach rings, doughnut tails, or thrust diamonds.

→ shock; → diamond.

The boundary over which the physical conditions undergo an abrupt change because of a → shock wave.

→ shock; → front.

A narrow region of abrupt, nearly discontinuous change in the physical characteristics of a medium in which the flow of a fluid changes from subsonic to supersonic. Across a shock wave there is always an extremely rapid rise in pressure, temperature, and density of the fluid.

→ shock; → wave.

A form of quartz that has a deformed microscopic structure caused by intense pressure which alters the crystalline structure of quartz along planes inside the crystal. It was first discovered after underground nuclear bomb testing. It is found worldwide at the boundary between Cretaceous and Tertiary rocks. This is further evidence (in addition to iridium enrichment) that the transition between the two geological eras was caused by a large meteorite impact.

→ shock; → impact.

Colloquial name for → meteor.

Shooting, from shoot (v.); M.E. shoten; O.E. sceotan "to shoot" (cf. O.N. skjota, Du. schieten, Ger. schießen), from PIE base *skeud- "to shoot, to chase, to throw;" → star.

Šahâb, → meteor.

1) Having little length. Not tall or high.
2) Lasting for only a small amount of time.

M.E. schort; O.E. sceort; cf. O.N. skorta "to be short of," skort "shortness;" O.H.G. scurz "short."

Kutâh "short," related to kucak "small," kudak "child, infant;" Mid.Pers. kôtâh "low," kôtak "small, young; baby;" Av. kutaka- "little, small."

A relatively low → resistance contact, usually accidental, between two points of an → electric circuit with initially different → potential. A short circuit brings about a flow of excess → electric current that can damage the circuit and present a danger for the user.

→ short; → circuit.

Gardrâhband, literally "link, bind, bond in circuit," from gardrâh, → circuit, + band, → band.

A comet with a period less than 200 years. Same as → periodic comet.

→ short; → period; → comet.

A variable star that has a relatively short period with respect to stars of similar types.

→ short; → period; → variable.

1) A deficiency in quantity.
2) The amount of such → deficiency.

From → short + suffix -age.

Kambud, from kam "little, few, deficient, scarce" + bud, from budan, → exist.