bâd-e tâbeši, ~ tâbešzâd
Fr.: vent radiatif
The loss of matter from the → photosphere due to the acceleration imparted to the outer layers of the star by photons created inside the star. The coupling between radiation and matter creates a → radiative acceleration that may exceed the → gravity. This mechanism is particularly important in → massive stars, since the luminosity is high and therefore the number of energetic ultraviolet photons important. Same as → line-driven wind.
radiatively driven wind
Fr.: vent radiatif
Same as → radiation-driven wind
rowzane-ye râdioyi (#)
Fr.: fenêtre radio
A range of electromagnetic radiation in the radio frequencies to which the Earth's atmosphere is transparent.
Fr.: fenêtre rectangulaire
A → window function that is constant inside a specified interval.
bâd-e xoršid, ~ xoršidi
Fr.: vent solaire
A mass outflow, consisting of protons, electrons, and other subatomic particles, expelled constantly from the solar corona at about 500 km per second. The solar mass-loss rate in this phenomenon amounts to about 2 x 10-14 solar masses per year, or about 106 tons per second. → stellar wind.
Fr.: vent stellaire
The steady flow of gas away from a star resulting in → mass loss. They range from gentle solar wind (2 x 10-14 solar masses per year) to violent winds some 10 billions times stronger (10-4 solar masses per year) for hot, massive stars.
Fr.: vent super-Eddington
A galactic-scale wind driven by the collective effect of a large number of → supernovae and → winds from → massive stars occurring in the central region of a galaxy. Superwinds have been invoked, among other things, as the source by which the → intergalactic medium is provided with → enriched gas (see, e.g. Heckman et al. 1990, ApJS 74, 833).
Fr.: galaxie à super-vent
A galaxy with → superwind characteristics. M 82 and NGC 4666 are among superwind galaxy candidates.
weak wind problem
parâse-ye bâd-e nezâr, ~ ~ kamzur
Fr.: problème de faible vent
weak-wind O-type star
setâre-ye O bâ bâd-e nezâr, ~ ~ ~ ~ kamzur
Fr.: étoile O de faible vent
A → main sequence → O star with low luminosity and surprisingly weak → stellar wind compared to "classical" dwarfs. The → mass loss rates are lower than 10-8 solar masses per year and the → modified wind momenta nearly 2 orders of magnitude smaller than that expected from wind models for typical O stars. Weak-wind O-type stars occur in both → metal-rich and → metal-poor environments. Their nature is not yet fully understood. same as → weak wind problem.
Fr.: tourbillon de vent
1) bâd (#); 2) picidan
Fr.: 1) vent; 2) s'enrouler
1a) Meteo.: Air in motion, especially a natural and perceptible movement of air
relative to the ground.
1) M.E., O.E. wind (cf. O.S., O.Fris., Du. wind, O.H.G. wind,
Ger. Wind, Goth. winds).
1) Bâd, from Mid.Pers. wâd "wind;" Av. vāta- "wind;"
cf. Skt. vāta- "wind, god of wind;" Gk. anemos "wind;"
L. ventus "wind" (Fr. vent); cognate with E. wind, as above.
farbâl-e bâdi, ~ pat bâd
Fr.: accrétion par vent
A quasi-spherical accretion that is likely to occur in a → high-mass X-ray binary (HMXB) when the optical star of → early spectral class (O-B) does not fill its → Roche lobe, but has a significant → mass loss via → stellar wind. In → close binary systems another accretion regime, → disk accretion, occurs when the optical star overfills its Roche lobe.
Fr.: effet de couverture du vent
A process whereby dense winds of very luminous O type stars modify the temperature and internal structure of the underlying photosphere by scattering back a considerable part of the coming photospheric radiation. Not to be confused with → line blanketing .
Thus called because the wind acts like a blanket and heats the photosphere * by reflecting its radiation; → wind.
Fr.: grumelage de vent
Fr.: luminosité de vent
The final kinetic energy of the → stellar wind expressed by: (1/2)Mdot.v∞2 = (1/2)(v∞/c)L For an O6 star, L ~ 3 x 105Lsun and v∞ ~ 2000 km s-1, which give a wind luminosity of ~ 1 x 1037 erg s-1, about 1% of the → stellar luminosity. See also → photon tiring limit.
Fr.: moment angulaire de vent
Fr.: rose des vents
A diagram showing the relative frequency of winds blowing from each of the 8 or 16 main points of the compass, sometimes within specified speed ranges, at a given location over a considerable period.
An object that is balanced on a rotating axis and indicates the direction of the wind. Also called a weather vane.
→ wind + vane "a blade, plate," O.E. fanafana "piece of cloth," O.H.G. fano, Ger. Fahne "flag, standard."