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

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.

The speed at which the → stellar wind is forced away from the star. Wind velocities of → hot stars are directly measured from → P Cygni profiles, which indicate velocities from several hundred to several thousand km s^-1. See also → escape velocity, → terminal velocity, → velocity law, → radiation-driven wind, → CAK model.

→ wind; → velocity.

The problem encountered in the explanation of the → spiral arms of galaxies if the material making up a spiral arm is static, that is remains in the arm. Since galaxies exhibit → differential rotation, stars near the center take less time to orbit the center than those farther from the center. The arm would, after a few → galactic rotations, become increasingly curved and wind around the → galaxy ever tighter until it ultimately disappears. This is inconsistent with observations.

1) Anything likened to a window in appearance or function.
2) In particular, the wavelength region in the electromagnetic spectrum that is relatively unaffected by atmospheric absorption. → atmospheric windows; → infrared window; → optical window; → radio window.

Window literally "wind eye," from O.N. vindauga, from vindr, → wind, + auga, → eye.

Rowzané, from rowzan "window, aperture;" Mid.Pers. rocânak "window," rôšn "light; bright, luminous," from Av. raocana- "bright, shining, radiant," raocah- "light, luminous; daylight," related to Mod.Pers. ruz "day," from Mid.Pers. rôc, O.Pers. raucah-; akin to Skt. rocaná- "bright, shining," roka- "brightness, light;" Gk. leukos "white, clear;" L. lux "light" (also lumen, luna); PIE base *leuk- "light, brightness." The Persian words rowšan "bright, clear," foruq "light," and afruxtan "to light, kindle" also belong to this family, as well as the E. light, Ger. Licht, and Fr. lumière; forusorx→ infrarouge.

A function whose value is zero outside a given interval. Applications of window functions include signal filtering and spectral analysis. The various types of windw functions include: → rectangular window, cosine window, triangular window, Gaussian window, Hanning window, and so on.

→ window; → function.

The fermented juice of grapes, made in many varieties, such as red, white, sweet, dry, still, and sparkling, for use as a beverage, in cooking, in religious rites, etc., and usually having an alcoholic content of 14 percent or less (Dictionary.com).

M.E., O.E. win, cognate with O.H.G. win, Du. wijn, Ger. Wein, from L. vinum "wine," from PIE *woin-o-, related Gk. word oinos.

Mey, variant mol "wine;" Mid.Pers. mad, may "wine;" Av. maδu- "wine;" cf. Skt. madhu- "wine, sweet drink, sweet;" Gk. methy "wine;" O.C.S. medu; Lith. medus "honey;" O.Irish mid; Welsh medd; Breton mez "mead;" O.E. medu; E. mead "fermented honey drink;" Russ. medved "(honey-eater) bear."
Bâdé, from Mid.Pers. bâdag, from O.Pers. *bātu- "wine" (from bātu-gara- "cup, bowl"); cf. Khotanese Saka bātaa- "wine;" O.Pers. *batiaka- "cup, bowl" (cf. Pers. bâdiyé "bowl") loaned in Gk. batiaké "bowl, cup."
Nabid, "wine, date-wine," ultimately from Proto-Ir. *paH- "to drink;" cf. Av. paitīš- "drink" in vīspô.paitīš- "having all sorts of drinks;" pitu- "juice, food;" Wakhi puv-, pəv-, pit-; Sanglechi pöv-/pövδ- "to drink;" Skt. pā- "to drink;" Gk. pinein "to drink;" L. bibere "to drink," related to potare "to drink."

1) Either of the two limbs of a bird allowing her to fly. → Pegasus.
2) Either of the large flat structures in an aircraft's body that provide the main source of lift.
3) In spectroscopy, same as → line wing.

M.E. wenge from O.N. vængr "wing of a bird, aisle, etc." (cf. Dan., Swed. vinge "wing").

Bâl "wing," Mid.Pers. bâl, variant of par / parr "feather, " with the conversion of p to b and r to l; Av. parəna- "feather;" cf. Skt. parnam; O.H.G. farn "fern;" PIE pornom "feather."

A spectral feature at 9850-10200 Å appearing in the spectrum of some late-type → M dwarfs. It is attributed to iron hybrid (FeH), a typical signature of the atmospheres of the coolest stars.

First detected by R. F. Wing and W. K. Ford (1969, PASP 81, 527); → band.

The season beginning at the → winter solstice, about December 22 and lasting until the → vernal equinox, about March 21.

M.E., OE; cf. O.Fris., Du. winter, O.S., O.H.G. wintar, Ger. winter, Dan., Swed. vinter, Goth. wintrus "winter"),

Zemestân "winter," related to zam "cold," Mid.Pers. zam, zamistân "winter;" Av. zimô "winter;" cf. Skt. hima- "cold, frost;" Ossetic zymæg/zumæg "winter;" Gk. xeimon "winter;" L. hiems "winter;" Lith. ziema "winter;" PIE *gheim- "snow, winter."

The moment in the northern hemisphere when the → Sun attains its lowest → declination of -23°26' (or -23°.44) with respect the → equator plane. It happens when the Earth's axis is orientated directly away from the Sun, on 21 or 22 December. During the northern winter solstice the Sun appears to be directly overhead at noon for places situated at → latitude 23.44 degrees south, known as the → tropic of Capricorn. The winter solstice can occur at any moment during the day. Two successive winter solstices are shifted in time by about 6 h. The winter solstice in the northern hemisphere is the → summer solstice in the southern hemisphere.

→ winter; → solstice..

A slender flexible thread or rod of metal.

M.E., O.E. wir, cf. O.N. viravirka "filigree work," Swed. vira "to twist," O.H.G. wiara "fine gold work."

Sim "wire," initially "strand of silver," from sim "silver," from Mid.Pers. asêm "silver," from Gk. asemon "without mark, uncoined, shapeless, formless," from argurion asemon "uncoined money." For semantic similarity, see → silver.

The quality or state of being → wise; knowledge of what is true or right coupled with just judgment as to action; sagacity, discernment, or insight (Dictionary.com). Wisdom is gained over the years through experience. It is the insight in knowing the probable outcome learned through experience. In contrast, → reason is using the → rational → reasoning to evaluate pros and cons in making a decision.

M.E.; O.E. wisdom, from wis "→ wise" + -dom. The first component is related to → vision and Pers. bin, didan "to see."

Xerad "understanding, judjement, intellect, wisdom;" Mid.Pers. xrad "reason, intellect, intelligence, wisdom, understanding;" O.Pers. xraθu- "wisdom;" Av. xratu- "intelligence, understanding, wisdom; will, purpose, council;" cf. Skt. krátu- "power, will-power;" Gk. kratos "power, strength."

Having the power of discerning and judging properly as to what is true or right; possessing discernment, judgment, or discretion (Dictionary.com).

From M.E. wis, wys, from O.E. wis ("wise"), cognate with Du. wijs, Ger. weise, Norw. and Swed. vis.

Xeradmand, from xerad, → wisdom, + -mand relatrion and possession suffix.

A → Wolf-Rayet star whose spectrum is dominated by emission lines of ionized nitrogen: N II 3995 Å, N III 4634-4661 Å, N III 5314 Å, N IV 3479-3484 Å, N IV 4058 Å, N V 4603 Å, N V 4619 Å, and N V 4933-4944 Å. This type is divided in sub-types WN2 to WN11.

W short for Wolf-Rayet star, N for → nitrogen.

An object showing signatures of both → WN Wolf-Rayet stars and → WC Wolf-Rayet stars in the same spectrum, originating from individual stars rather than from WN + WC → binary systems. Such a WN/WC signature implies that the surface composition of the star is → nitrogen and → carbon enriched. This hybrid state results from a mixing process between He-burning → convective core and the overlying nitrogen enriched layers. According to model predictions, this situation corresponds to a short transition phase, lasting 10³ to 10⁴ years, during which a WN star evolves into a WC star. The WN/WC stars so far detected are all of early types.

→ WN Wolf-Rayet; → WC Wolf-Rayet.

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N III 4634-4641, 5314 Å as strong as N II 3995 Å, Balmer lines, He I with → P Cygni profile.

W, from → Wolf-Rayet; N, from → nitrogen; → star.