Fr.: processus de Blandford-Zanjek
A mechanism for the extraction of energy from a rotating → Kerr black hole. It relies on the assumption that the material → accreted by a → black hole would probably be → magnetized and increasingly so as the material gets closer to the → event horizon. Since all black holes of current astrophysical interest are probably accreting from magnetized disks, this has led to suggestions that the Blandford-Znajek process plays a vital role in → active galactic nuclei (AGN) and other accreting black hole systems. The power, P, generated is given by: P = (4π/μ0) B2RS2c, where B is the → magnetic field of the → accretion disk, and RS is the → Schwarzschild radius of the black hole. As an example, for a 108 solar mass black hole with a 1 T magnetic field, the power generated is approximately 2.7 × 1038 W. In perspective, the annual energy consumption of the world is estimated around 5 × 1020 J. The example case presented produces more energy in a single second than the entire globe consumes in a year. While this is a bold claim to make, it is only an example case where not all the energy produced is extractable as useable energy. However, at that point, even a system which is less that < 10-15 % efficient would be sufficient to supply enough energy to power the world for a full year. Of course, the system itself is limited in its lifetime due to the extraction of energy by slowing down the rotation of the black hole. Hence, the system can only exist as long as the black hole has angular momentum, continuing to rotate. At some point, the rotation will cease and the energy source will be unusable (D. Nagasawa, PH240, Stanford University, Fall 2011).
Blandford, R. D., & Znajek, R. L., 1977, MNRAS 179, 433; → process.
1) A large piece of thick cloth for use as a bed covering, animal covering, etc,
enabling a person or animal to retain natural body heat.
From M.E., from O.Fr. blanchet, diminutive of blanc "white; white cloth."
Patu "blanket; a kind of woolen cloth," Kermâni dialect poto "wollen; woolly;" cf. Skt. patta- "cloth, colored or fine cloth."
Fr.: modèle à effet de couverture
Fr.: effet de couverture
Fr.: effet de couverture
Blazar, a combination of BL Lac and quasar.
Fr.: flambée; blaze
O.E. blæse "a torch, flame," from P.Gmc. *blason, from PIE *bhel- "to shine."
Beliz, from Lori beleyz "flame, blaze," Kordi belise "flame, blaze," Mid.Pers. brâh, Av. braz- "to shine, gleam, flash, radiate," cf. Skt. bhâ- "to shine," bhrajate "shines, glitters," O.H.G. beraht "bright," O.E. beorht "bright;" PIE *bhereg- "to shine."
Fr.: angle de blaze
The angle between the operating facet of the grooves and the overall plane of a diffraction grating.
→ blaze; → angle.
Fr.: longueur d'onde de blaze
The wavelength in a given diffraction order for which the efficiency curve reaches its maximum.
Fr.: réseau échelette
Turi, noun from tur "a net, a fishing net;" belizi adj. from beliz, → blaze.
Fr.: effet Blazhko
A long term, generally irregular modulation of → light curves of a large subclass of → RR Lyrae stars. Most of the modulations occur on the time scale of some 60 periods, although the range extends from some tens to some hundreds of periods. Since its discovery over a hundred years ago, a number of explanations have been proposed for this effect, but its nature is still a matter of investigation. The explanations include: closely spaced pulsation modes, a modal 1 : 2 resonance, an oblique rotator model, a non-radial modal interaction, convective cycles, and nonlinear resonant mode coupling between the 9th overtone and the fundamental mode (see, e.g., R. Buchler and Z. Kolláth 2011, astro-ph/1101.1502).
Named after Sergei N. Blazhko (1870-1956), a Russian astronomer who discovered the effect for the star EW Dra (1907, Astron. Nachr. 175, 325); → effect.
Fr.: étoile à effet Blazhko
A star showing the → Blazhko effect.
The capcity of a diffraction grating, in certain configurations, to concentrate a large percentage of the incident light into a specific diffraction order.
Blazing, noun from → blaze.
Belizeš, noun from beliz "blaze."
General: A flaw or defect.
From O.Fr. blemiss "to turn pale," extended stem of blemir, blesmir "to injure, make pale."
Âk "defect, blemish," Mid.Pers. ak, âk "evil, harm," Av. aka- "bad, wicked;" cf. Skt. aka- "pain , trouble."
1) tuham; 2) tuham šodan
Fr.: 1a) blend; 1b) mot-valise; 2) mélanger
1a) Description of two or more adjacent → spectral lines
which are mixed due to insufficient → resolving power
of the → spectrograph.
M.E., from O.N. blanda; akin to O.E. blandan "to mix," Lith. blandus "impure, cloudy."
Tuham, from tu "inside" + ham "together," → com-.
xatthâ-ye tuham, tânhâ-ye ~
Fr.: raies mélangées
→ Spectral lines intermingled.
Unable to see; sightless.
M.E., from O.E. blind "blind," akin to Du., Ger. blind, O.N. blindr, Goth. blinds "blind."
Kur "blind," variants kul "squint-eyed," kolok, kalek, kelek, kalâž, kâž, kâj, kâc "squint-eyed," Lori, Laki, Kurd. xêl "cross-eyed, squinting;" Mid.Pers. kôr "blind;" akin to O.Irish coll "one-eyed;" M.Irish goll "blind;" Gk. (Hes.) kellas "one-eyed;" Skt. kāná- "blind of one eye;" PIE *kolnos "one-eyed." The Pers. luc "crossed-eyed" may be related to a separate group containing L. lusca, luscus "one-eyed" (Fr. louche "squinting").
The state or condition of being sightless.
1) To close and open the eyes rapidly.
M.E. blinken, variant of blenken "to blench;" cf. Du. and Ger. blinken.
Možidan, from možé "eyelash," Mid.Pers. mec "eyelash," mecitan "to blink," cf. Skt. mes "to open the eyes," O.C.S. po-mežiti "to close the eyes." → twinkling.
Fr.: comparateur à clignotement
An instrument for comparing two photographs of the same stellar field, taken at different times, by quickly alternating from one to the other. The purpose of the comparison is to detect subtle changes in the position or brightness of the stars.