Fr.: transition hyperfine
A high luminosity star with absolute visual magnitude around -10, about 106 times as luminous as the Sun. Hypergiant stars are evolved → massive stars belonging to the luminosity class Ia+ or Ia0. Their spectra show very broadened emission and absorption lines resulting from the high luminosity and low surface gravity which favor strong → stellar wind. See also → Humphreys-Davidson limit; → yellow hypergiant.
Hyperion (Saturn VII)
The sixteenth of → Saturn's known → natural satellites. It is shaped like a potato with dimensions of 410 x 260 x 220 km and has a bizarre porous, sponge-like appearance. Many of the sponge holes or craters have bright walls, which suggests an abundance of → water → ice. The crater floors are mostly the areas of the lowest → albedo and greatest red coloration. This may be because the average temperature of roughly -180 °C might be close enough to a temperature that would cause → volatiles to → sublimate, leaving the darker materials accumulated on the crater floors. Hyperion is one of the largest bodies in the → Solar System known to be so irregular. Its density is so low that it might house a vast system of caverns inside. Hyperion rotates chaotically and revolves around Saturn at a mean distance of 1,481,100 km. It was discovered by two astronomers independently in 1848, the American William C. Bond (1789-1859) and the British William Lassell (1799-1880).
Hyperion, in Gk. mythology was the Titan god of light, one of the sons of Ouranos (Heaven) and Gaia (Earth), and the father of the lights of heaven, Eos the Dawn, Helios the Sun, and Selene the Moon.
A condition of the eye that occurs when light rays entering the eye are focused behind the retina; also called farsightedness, hyperopia, long sight (opposed to → myopia).
Durbini "farsightedness," from dur "far" (Mid.Pers. dūr "far, distant, remote;" O.Pers. dūra- "far (in time or space)," dūraiy "afar, far away, far and wide;" Av. dūra-, dūirē "far," from dav- "to move away;" cf. Skt. dūrá- "far; distance (in space and time);" PIE base *deu- "to move forward, pass;" cf. Gk. den "for a long time," deros "lasting long") + bin- "to see" (present stem of didan; Mid.Pers. wyn-; O.Pers. vain- "to see;" Av. vaēn- "to see;" Skt. veda "I know;" Gk. oida "I know," idein "to see;" L. videre "to see;" PIE base *weid- "to know, to see") + -i noun suffix.
An unstable elementary particles, belonging to the class called → baryons, which have greater mass than the neutron but very short lives (10-8 to 10-10 seconds).
hypervelocity star (HVS)
Fr.: étoile hypervéloce
A star whose velocity is so great that it will escape the
→ gravitational potential of our
→ Galaxy. Depending on the location and direction of
motion, this criterion typically corresponds to a stellar velocity in
the Galactic → rest frame larger than
400 km s-1, and up to about 1200 km s-1.
The nature of the HVSs spans a wide range of types from
→ OB stars, to metal-poor
→ F-type stars and G/K dwarfs. While there is evidence from many
late-type B HVSs in the → halo
to originate from the Galactic
→ supermassive black hole (SMBH),
other HVSs seem to originate from the → galactic disk.
HVSs can obtain their large velocities from a number of different processes:
Fr.: opérateur d'identité
An operator which takes a real number to the same real number.
Fr.: température d'inflammation
The minimum temperature to which a fuel must be heated in order to initiate self sustained combustion independent of another heat source.
Fr.: inperare (L.)
Latin verb meaning "to command, rule, reign."
L. imperare "to command, give orders, exercise authority," from → in- "into, in" + parare "to make ready, supply, order," related to parire "produce, give birth to," from PIE root *pere- "to produce, procure;" cf. Skt. prthukah "child, calf, young of an animal;" Gk. poris "calf, bull;" Czech spratek "brat, premature calf;" Lith. periu, pereti "to brood;" O.H.G. farro, Ger. Farre, Du. varre "bull," O.E. fearr "bull;" see below for possible Iranian cognates.
Parmâtidan, from BMP plm'(d)y "to command, order," Sogd. framat- "to command," variants of farmudan, farmâyidan "to command, to order," ultimately from prefixed Proto-Ir. *fra-maH-, from *maH- "to measure," → experiment.
1) parmâte; 2) parmâti
Fr.: 1) inpératif; 2) impériux
1a) A command or order.
From L.L. imperativus "pertaining to a command," from imperat-, p.p. stem of → imperare "to command."
Parmât, noun from present stem of parmâtidan, → imperare; parmâtii, adj. from parmât.
kâte-ye parmâti, ~ farmâni
Fr.: cas impératif
The grammatical mood of a verb that expresses a command or a request, as in close the door!.
In an imperative manner.
Not perfect; faulty or incomplete.
A fault, flaw, or undesirable feature; the state or condition of being imperfect.
parmâtyâri, parmâtgâni, šâhi, šâhâne, šâhanšâhi
Of, relating to, or suggestive of an empire or a sovereign, especially an emperor or empress (TheFreeDictionary).
Adjective of → empire.
1) The extension of a nation's authority by territorial acquisition or by
the establishment of economic and political dominance over other nations.
Fr.: opérateur intégral
Math.: An operator whose inverse is a differential operator.