An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

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.

→ radiation; → drive; → wind.

Same as → radiation-driven wind

→ radiative; → drive; → wind.

A range of electromagnetic radiation in the radio frequencies to which the Earth's atmosphere is transparent.

→ radio; → window.

A → window function that is constant inside a specified interval.

→ rectangular; → window.

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.

→ solar; → wind.

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.

→ stellar; → wind.

A → stellar wind accelerated by radiation pressure in the continuum from a star with a luminosity above the → Eddington limit.

→ super-; → Eddington limit; → wind.

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).

→ super-; → wind.

A galaxy with → superwind characteristics. M 82 and NGC 4666 are among superwind galaxy candidates.

→ superwind; → galaxy.

The discrepancy between the observed → mass loss rates and the predicted values for → weak-wind O-type stars.

→ weak; → wind; → problem.

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.

→ weak; → wind; → O-type star.

A general term for a small-scale, rotating column of air. More specific terms are → dust whirl, → dust devil, → waterspout, and → tornado.

→ whirl; → wind.

1a) Meteo.: Air in motion, especially a natural and perceptible movement of air relative to the ground.
1b) Astro.→ radiation-driven wind; → solar wind; → Galactic wind; → stellar wind.
2) To change direction; turn; to have a circular or spiral course or direction; to coil or twine about something.

1) M.E., O.E. wind (cf. O.S., O.Fris., Du. wind, O.H.G. wind, Ger. Wind, Goth. winds).
2) M.E. windan, from O.E. windan "to turn, twist, curl," cognate with Du. winden, O.H.G. wintan, Ger. winden, from PIE *wendh- "to turn, wind, weave."

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.
2) Picidan "to twist, entwine, coil," → spiral.

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.

→ wind; → accretion.

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.

The inhomogeneous property of a → radiation-driven wind, or the physical mechanism accounting for the → clumped wind.

→ clumpy; → wind.

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.

→ wind; → luminosity.

The product of the → mass loss rate and → terminal velocity used in the → radiation-driven wind theory. See also → modified wind momentum.

→ wind; → momentum.

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.

Translation of Ger. Windrose "compass card," from Wind→ wind + Rose "rose," → Rosette Nebula.

Bâdnaqš, from bâd, → wind, + naqš "painting, engraving, printing," → map.

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."

Bbâdnemâ "wind indicator," from bâd, → wind, + nemâ, from nemudan, → planetarium.