Fr.: pole de l'écliptique
Either of the two points on the celestial sphere that are 90° above and below the plane of ecliptic. The north ecliptic pole lies in → Draco, and the south ecliptic pole in → Dorado. Due to → precession, the → celestial pole moves in a circle around the ecliptic poles once every 25,800 years.
Fr.: système écliptique
Coordinate system with the ecliptic as the fundamental plane.
A combining form meaning "house, household, environment, nature, natural habitat."
Ultimately from Gk. oikos "house," cognate with L. villa "country house, farm," related to vicus "village, group of houses; " cf. Av. vis- "homestead, community;" O.Pers. viθ- "house, royal house, farm;" Mid.Pers. wis "village;" dialectal Pers. wiš-, vīš- "to set (of Sun)," wīs- "to enter" (Cheung 2007); Skt. viś- "settlement, house, tribe, people;" Goth. weihs "village;" Lith. viešpats "master of the house;" PIE *ueik'- "to settle (down)."
Bum-, from bum "region, land, a mansion or place where one dwells in saftey; nature, disposition;" Mid.Pers. bûm "land, earth, country;" O.Pers. būmi- "place of being/living, land, region;" Av. būmī- "earth," from bav- "to be, become, take place;" cf. Skt. bhūmi- "land, region;" PIE *bheu- "to be, come into being, become" (cf. Gk. phu- "become," phuein "to bring forth, make grow;" L. fui "I was" (perf. tense of esse), futurus "that is to be, future;" Ger. present first and second person sing. bin, bist; E. to be; O.Ir. bi'u "I am;" Lith. bu'ti "to be;" Rus. byt' "to be").
1) The scientific discipline that is concerned with the relationships between
living organisms and their past, present, and future environments.
1) Pertaining to the production, distribution, and use of income, wealth, and
Adjective, from → economics.
Fr.: croissance économique
An increase in the output that an economy produces over a period of time.
1) Avoiding waste or extravagance; thrifty.
The science that deals with description and analysis of the production, distribution, and consumption of goods and services.
1) To practice economy; avoid waste or extravagance.
1) Thrifty and efficient use of material resources of a community, society, or
household; frugality in expenditures.
From M.Fr. economie, → economics.
Bumdât, back formation from bumdâti, → economic.
From → eco- "house, dwelling place," + poiesis a combining form meaning "making, formation; poetry," from Gk. poesy, from poiein "to make, compose." Coined by Robert Hall Haynes (1931-1998), a Canadian geneticist and biophysicist.
Bum-âfarini, literally "creating environment," from bum "region, land," → eco- + âfarini "creation," from âfaridan, âfarin- "to create," from Mid.Pers. âfridan, âfrin- "to praise, bless; create," ultimately from Proto-Iranian āfrīta-, from prefixed frī- "to praise; to like;" cf. Av. frāy- "to satisfy, propitiate, pray;" Skt. prī- "to gladden, show favor to," prīta- "glad;" Gk. praus "gentle."
The space around a star in which a planet would experience external conditions that are not incompatible with the existence of life.
Any geographic area that includes all of the organisms and nonliving parts of their physical environment.
hadd-e Eddington (#)
Fr.: limite d'Eddington
The theoretical upper limit of → luminosity at which the → radiation pressure of a light-emitting body would exceed the body's → gravitational attraction. A star emitting radiation at greater than the Eddington limit would break up. The Eddington luminosity for a non-rotating star is expressed as: LEdd = 4πGMmpcσT-1, where G is the → gravitational constant, M the star mass, mp the → proton mass, c the → speed of light, and σT the → Thomson cross section. It can also be written as LEdd = 4πGMcκ-1, where κ is the → opacity. In terms of solar mass, the Eddington limit can be expressed by: LEdd = 1.26 × 1038 (M/Msun) erg s-1. See also → rotational Eddington limit.
Named after Arthur Stanley Eddington (1882-1944), prominent British astrophysicist; → limit.
Fr.: luminosité d'Eddington
Same as → Eddington limit.
Fr.: paramètre d'Eddington
A → dimensionless parameter indicating the degree to which a star is close to the → Eddington limit. It is expressed as Γ = L / LEdd = κ L / (4πGMc), where L and M are the star luminosity and mass respectively, κ is the opacity, c the speed of light, and G the → gravitational constant. At the Eddington limit, Γ = 1, the star would become unbound. Because stellar luminosity generally scales with a high power of the stellar mass (L∝ M3-4), → massive stars with M larger than 10 Msun generally have electron Eddington parameters of order Γ ≅ 0.1-1.
After Arthur Stanley Eddington (1882-1944), prominent British astrophysicist; → parameter.
giti-ye Eddington-Lemaître (#)
Fr.: Univers d'Eddington-Lemaître
A theoretical model in which the → cosmological constant plays a crucial role by allowing an initial phase that is identical to the Einstein static Universe. After an arbitrarily long time, the Universe begins to expand. The difficulty with this model is that the initiation of galaxy formation may actually cause a collapse rather than initiate an → expansion of the Universe.
Eddington-Sweet time scale
marpel-e zamâni-ye Eddington-Sweet
Fr.: échelle de temps d'Eddington-Sweet
The time required for the redistribution of → angular momentum due to → meridional circulation. The Eddington-Sweet time for a uniformly → rotating star is expressed as: τES = τKH . GM / (Ω2 R3), where τKH is the → Kelvin-Helmholtz time scale, R, M, and L designate the radius, mass, and luminosity respectively, Ω the → angular velocity, and G the → gravitational constant. The Eddington-Sweet time scale can be approximated by τES≅ τKH / χ, where χ is the ratio of the → centrifugal force to → gravity. For the Sun, χ ≅ 10-5 resulting in an Eddington-Sweet time scale which is too long (1012 years), i.e. unimportant. In contrast, for a rotating → massive star χ is not so much less than 1. Hence the Eddington-Sweet circulation is very important in massive stars.
Named after the prominent British astrophysicist Arthur S. Eddington (1882-1944), who was the first to suggest these currents (in The Internal Constitution of the Stars, Dover Pub. Inc., New York, 1926) and P. A. Sweet who later quantified them (1950, MNRAS 110, 548); → time scale.
A deviation in the steady flow of a fluid causing a vortex-like motion running
contrary to the general flow.
Late M.E., from O.E. ed- "turning" + ea "water;" akin to O.N. itha.
Gižâv, from dialectical Kurd. "whirlpool," from giž "turning," Pers. gij "giddy-headed, vertigio;" Laki géž "whirlpool," vagéža "whirlwind" + âv, variant âb "water" (Mid.Pers. âb "water;" O.Pers. ap- "water;" Av. ap- "water;" cf. Skt. áp- "water;" Hitt. happa- "water;" PIE āp-, ab- "water, river;" cf. Gk. Apidanos, proper noun, a river in Thessalia; L. amnis "stream, river" (from *abnis); O.Ir. ab "river," O.Prus. ape "stream," Lith. upé "stream;" Latv. upe "brook").
jarayân-e Foucault (#)
Fr.: courant de Foucault
An induced current circulating in masses of metal moving in a magnetic field or located in a changing magnetic field. Also known as → Foucault current.