| 释义 |
luminosity|l(j)uːmɪˈnɒsɪtɪ|
[f. luminous: see -ity, -osity.]
1. a. The quality or condition of being luminous.
1634Bp. Hall Contempl., N.T. iv. vii, As it is in the sun..the luminosity of it being no whit impaired by that perpetual emission of lightsome beams. 1851–9Owen in Man. Sci. Enq. 369 The phenomena of oceanic luminosity. 1865E. C. Clayton Cruel Fortune II. 148 To impart additional luminosity to your ideas. 1871Darwin Desc. Man I. x. 345 The purpose of the luminosity in the female glowworm is..not understood. 1895Zangwill Master ii. i. 120 Luminosity of colour, richness of handling, grip of composition.
b. The effectiveness of light of any particular wavelength in producing the sensation of brightness when perceived.
[1888Amer. Jrnl. Sci. CXXXVI. 359 While..the luminosity of any spectral ray increases proportionately to the heat in this ray, and indeed is but another manifestation of the same energy..there is..a failure to recognize how totally different optical effects may be produced..according to the wave-length.] 1898Astrophysical Jrnl. VII. 303 That particular property of any color which determines its value as an illuminant is called its ‘luminosity’. 1936Proc. R. Soc. A. CLV. 664 The relative luminosity (visibility) in the red region has been measured..as far as 770 mµ. In this paper an account is given of measurements up to 900 mµ. At this wavelength the relative luminosity is one-sixty millionth of that at 556 mµ. 1950F. H. Adler Physiol. Eye xx. 645 The luminosity of any one wave length is usually compared to that of 550 mµ. 1966C. W. Wilman Seeing & Perceiving xiv. 116 Curve Ph in Fig. 78 represents the relative luminosity (brightness) of various parts of the spectrum.
c. Astr. The intrinsic brightness of a heavenly body (as distinct from its apparent brightness, diminished by distance); the rate of emission of electromagnetic radiation (visible or invisible) within any part of the spectrum.
1906Astrophysical Jrnl. XXIII. 248 Prevailing opinion.. admits the presence in the heavens of at least a few stars of extraordinary intrinsic brilliancy{ddd}stars having a luminosity exceeding that of the Sun by ten-thousand fold or more. 1924H. Dingle Mod. Astrophysics vi. 74 By brightness we mean—at present, at any rate—the apparent brightness of a star, which will be determined by the star's distance from us as well as by its intrinsic luminosity. 1930R. H. Baker Astron. ix. 369 The apparent magnitude of a star relates to its brightness as we observe it, depending on its real brightness, or luminosity, and on its distance. 1974Nature 1 Mar. 34/2 We have..assumed a thermal spectrum, with an electron temperature of 2 × 106 K, in deriving an upper limit to the X-ray luminosity of the source. Ibid., A 3σ upper limit was obtained to the source luminosity of 4·0 ({pm}1·0) × 1032 erg s-1 for the energy range 0·5 to 1·5 keV.
2. Something luminous; a luminous point or area.
1853Kane Grinnell Exp. xxvii. (1856) 223, I thought I saw a luminosity overhead. 1873Browning Red Cott. Nt.-cap 232 Then his face grew one luminosity. 1895Zangwill Master ii. ii. 142 The strange warm luminosities Matt professed to see on London tiles.
3. Special Comb.: luminosity curve, a graph showing how emitted energy, or perceived brightness, varies with wavelength; luminosity function Astr., a function giving the number or proportion of heavenly bodies with an absolute magnitude equal to, or greater than, any chosen value.
1886Abney & Festing in Phil. Trans. R. Soc. CLXXVII. 425 By successive alterations in the distance of the comparison-light other pairs of points in the spectrum are determined until the limits of the visible spectrum are reached. The curves of intensities of different parts of the spectrum plotted from these observations will be found to be fairly smooth. This curve we call the ‘luminosity curve’. Ibid. 452 We..determined the luminosity-curve of a candle. 1900Astrophysical Jrnl. XI. 220 (heading) Determining the luminosity curve of the solar spectrum. 1937Nature 6 Mar. 409/2 The maximum of this luminosity curve was at 510 mµ. This was a mean value for forty-eight young observers. 1941J. D. Cobine Gaseous Conductors xiii. 514 The luminosity curve for an incandescent lamp is shifted slightly toward the long wave lengths compared with sunlight. 1951Proc. IRE XXXIX. 1143/2 The luminosity curve expresses the relation..between the luminance and the radiance of spectrum colors. Ibid. 1144/1 Based on the new definition of the lumen, and on the new International Temperature Scale, the peak value of the luminosity curve corresponds to 680 lumens per watt.
1924Astrophysical Jrnl. LIX. 13 The comparison..is easily made with the aid of what may be called the apparent luminosity function..which expresses the frequencies of absolute magnitudes among the stars brighter than m0. 1958Ibid. Suppl. III. 211 Distances of galaxies are correlated with their apparent magnitude; however the uncertainty of the luminosity function of galaxies complicates and weakens the statistical treatment.
Add:[1.] d. Particle Physics. A parameter of a colliding-beam accelerator, equal to the ratio of the rate of interactions to the reaction cross-section, and proportional to the product of the rates of arrival of particles in the two beams divided by the cross-sectional area of the intersecting region.
1964F. Amman et al. in Proc. Internat. Conf. High Energy Accelerators 1963 250/2 The interaction rate per beam crossing region, ṅ for an event whose cross section is σ..is given by: ṅ= ..= Lσ (events/sec)..; the quantity L, measured in cm-2.s-1 or cm-2.h-1 , includes all the ring parameters and is called luminosity. 1976Physics Bull. Apr. 159/2 In general, colliding beam devices suffer in comparison with accelerators and conventional solid targets from a relatively low beam-beam interaction rate (or ‘luminosity’) at the intersection. 1980Nature 7 Feb. 515/2 As the luminosity of storage rings increases rapidly with energy, it is hoped to raise the present 50 per day event rate by a factor of ten. 1985Sci. Amer. June 64/2 The luminosity of each beam of the SSC is to be 1033 per second per square centimeter. |