Fr.: source atoll
→ atoll; the name derives from the fact that on X-ray → color-color diagrams these sources often resemble a band of points at constant hard X-ray color, with "islands" of points appearing on time-scales of weeks and months.
Fr.: source cohérente
One of two light beams derived from the same source in → interference experiments. It is impossible to obtain interference from two separate sources because their → wavefronts do not have a constant → phase difference. In → Young's experiment, → Fresnel's biprism, → Fresnel's mirrors, and → Lloyd's mirror the two sources always have a point-to-point correspondence of phase, since they are both derived from the same source.
compact radio source
xan-e râdioyi-ye hampak
Fr.: source radio compacte
An object emitting intense energy in radio wavelength from a small, unresolved central region.
discrete radio source
xan-e râdioyi-ye jodâ
Fr.: radiosource discrète
A localized source on the celestial sphere that can be observationally separated at radio wavelengths from its background emission.
double-lobed radio source
xan-e râdioyi bâ lap-e dotâyi
Fr.: radio source à double lobe
A → galaxy that emits radio energy from two regions located on opposite sides of the galaxy.
Fr.: source étendue
In radio astronomy, a source whose angular extent could be measured, as distinguished from a point source.
xan-e partowhâ-ye gâmma
Fr.: source de rayons gamma
1) An astronomical object that emits → gamma rays.
Fr.: source de bruit
An electronic device designed to generate known amounts of radio noise in order to test and calibrate the receivers of radio telescopes.
Fr.: observation hors source
An observation when the telescope is pointed away from the source in order to measure the sky background contribution.
xan-e OH (hidroksil)
Fr.: source OH
An astronomical source emitting microwave radiation characteristic of the hydroxyl OH molecule, especially one showing a maser effect. OH sources are found in molecular clouds in interstellar medium and in the cool envelopes of evolved stars.
OH, chemical compound hydroxyl; → source.
Fr.: observation sur la source
In comparison with → off-source observation, an observation which is concerned with the source itself.
To obtain under contract with an outside supplier.
noqté xan, pandé xan, xan-e noqtevâr, pande-ye ~
Fr.: source ponctuelle
A source of radiation at a great distance from the observer; an ideal source of infinitesimal size.
quasi-stellar radio source
râdio-xan-e cunân setâré, ~ ~ setâré-vaš
Fr.: radiosource quasi-stellaire
A quasar with detectable radio emission.
râdio-xan, xan-e râdioyi
Fr.: radio source, source radio
A point or small portion of the sky giving stronger radio emission than the sky in its vicinity.
Fr.: source de référence
An astronomical source in a field used as a reference for the detection of another object, astrometry, etc.
1) A source of supply, support, or aid, especially one that can be readily drawn
upon when needed.
General: Any thing or place from which something comes, arises, or is obtained.
M.E., from O.Fr. sourse "a rising, beginning, fountainhead of a river or stream," from p.p. of sourdre "to rise, spring up," from L. surgere "to rise," → surge.
Xan "source," variant xân (Gilaki xoni, Tabari xoni,Laki kyani, Tâleši xâni, xoni,); Mid.Pers. xân, xânig "source, spring," Av. xâ-, xan- "source, fountain, spring," xayana- "belonging to a spring;" cf. Khotanese khâhâ- "spring, fountain;" Skt. khâ'- "spring, source."
Fr.: fonction source
For a radiating material, the ratio of emissivity to opacity.
transient X-ray source
xan-e partow-e iks-e gozarâ
Fr.: source de rayons X transitoire
An X-ray source that appears suddenly in the sky, strongly increases its intensity over a few days, and then declines with a lifetime of several months.