1) Dimming of light by an intervening medium (the Earth's atmosphere or the interstellar medium).
It is usually due to both scattering and absorption.
Noun of extinct, from L. extinctus, p.p. of extinguere "to quench, wipe out," from → ex- "out" + stinguere "to quench," from PIE base *steig- "to prick, stick, pierce;" cf. Mod.Pers. tiz, tež, tig, tej, tij, tiq "sharp;" Av. tiγra- "pointed," tiγray- "arrow;" → deblur.
Xâmuši, noun of xâmuš "extinguished; silent," Mid.Pers. xâmôš "silent;" cf. Skt. amrs- "to bear patiently."
Fr.: coefficient d'extinction
Gradient of apparent magnitude with air mass.
Fr.: correction d'extinction
In → photometric calibration, the correction for energy loss undergone by radiation due to the → atmospheric extinction. Extinction correction is done using → standard stars observed at different → airmasses.
Fr.: courbe de l'extinction interstellaire
A graph representing the variation of the → interstellar extinction against → wavelength. Usually it displays the → normalized values of extinction as a function of (the → inverse) of the wavelength (in → microns). See, e.g., Sandage & Mathis, 1979, Ann. Rev. Astron. Astrophys. 17, 73.
Fr.: étoiles d'extinction
Stars specifically observed at selected air masses in view of determining the atmospheric extinction coefficients.
A facility at → European Southern Observatory (ESO)'s → La Silla Observatory funded by the European Research Council and the French Agence National de la Recherche with the purpose of detecting and studying → transiting → exoplanets. ExTrA will search for Earth-sized planets orbiting nearby → red dwarf stars. It uses three 0.6-metre telescopes. They regularly monitor the amount of light received from many red dwarf stars and look for a slight dip in brightness that could be caused by a planet passing across a star's disk and obscuring some of its light. The three ExTra telescopes collect light from the target star and four comparison stars and that light is then fed through optical fibres into a → multi-object spectrograph. This innovative approach of adding → spectroscopic information to traditional photometry helps mitigate the disruptive effect of Earth's atmosphere, as well as effects introduced by instruments and detectors, thus increasing the precision achievable.
ostar-, borun- (#)
Prefix meaning "outside; beyond the scope of; in addition to what is used or expected." Also extro-.
M.E., from L. extra, adverb and preposition, "outside, except, beyond," from exter "outward, on the outside."
Ostar-, from os-, → ex-, + -tar comparative suffix (Mid.Pers. -tar; Av. -tara; PIE base *-tero); borun-, from borun "out, the outside" (Mid.Pers. bêron, from bê "outside, out, away" + rôn "side, direction;" Av. ravan- "(course of a) river").
Of, pertaining to, or dealing with the space beyond the Milky Way.
axtaršenâi-ye ostar-kahkašâni, ~ borun-kahkašâni
Fr.: astronomie extragalactique
The branch of astronomy that deals with objects beyond the Milky Way, especially galaxies and quasars.
extragalactic background light (EBL)
nur-e paszimine-ye ostarkahkeši
Fr.: lumière du fond extragalactique
The integrated intensity of all of the light emitted throughout the history of the Universe across the whole of the → electromagnetic spectrum, including those which are not individually detected. The EBL spectrum includes cosmological backgrounds associated with either primordial phenomena, such as the → cosmic microwave background radiation (CMBR), or photons emitted by stars, galaxies and → active galactic nuclei (AGN) due to → nucleosynthesis or other → radiative processes, including → dust scattering, → absorption and reradiation. The EBL may also contain signals that are diffuse and extended, including high-energy photons associated with dark matter particle decays or annihilation.
1) Beyond what is usual, ordinary, regular, or established.
Fr.: rayon extraordinaire
Math.: To estimate the value of a result outside the range of a series of known values.
From borun, → extra- + yâftan, yâbidan "to find, discover; to obtain, acquire;" Mid.Pers. ayâftan, ayâpênitan "to reach, attain;" Manichean Mid.Pers. 'y'b "to attain;" Parthian, Sogdian (+ *pati-) pty'b "to reach, obtain;" Av. ap- "to reach, overtake," apayeiti "achieved, reached;" Skt. âp- "to reach, gain," âpnoti "reaches, gains;" Gk. hapto, haptomai "to touch, cling to, adhere to;" L. apiscor "touch, reach;" PIE base *ap- "to take, reach."
Predicting the value of unknown data points by projecting a function beyond the range of known data points.
Verbal noun of → extrapolate.
Not belonging to the → solar system; outside, or originating outside, the solar system.
Fr.: planète extrasolaire
Fr.: système extrasolaire
1) (adj.) Of or from outside the limits of the Earth.
Fr.: vie extraterrestre
Life that may exist and originate outside the planet Earth.
Farthest from the center or middle; outermost; exceeding the bounds of moderation. → extreme adaptive optics; → extreme HB star; → extreme horizontal branch star; → extreme infrared; → extreme mass ratio inspiral; → extreme ultraviolet; → extremely metal-poor star.
From L. extremus "outermost, utmost," superlative of exterus, "outer," comparative of ex "out of," → ex-.
Ostom "outermost, utmost" (Av. (ustəma- "outermost, highest, ultimate"), superlative of ost "out," → ex-, + -tom superlative suffix, from Mid.Pers. -tom (xwaštom "most pleasant," nevaktom "best," wattom "worst"), from O.Pers. -tama- (fratama- "first, front"); Av. -təma- (amavastəma- "strongest," hubaiδitəma- "most sweet-scented," baēšazyôtəma- "most healing," fratəma- "first, front"); cf. Skt. tama-.