Fr.: source atoll
A member of a class of → low-mass X-ray binary systems containing low-magnetic field → neutron stars. They have soft spectra and no pulsations. An example is 4U 1705-44. See also → Z source.
→ 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.
→ compact; → radio source.
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.
→ off-; → source; → observation.
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.
→ on-; → dource; → observation.
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.
From Fr. ressourse, from O.Fr. resourdre "to rally, raise again," from L. resurgere "rise again," → re-, + → source.
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.
→ transient; → X-ray source.