Solar Physics

, Volume 212, Issue 2, pp 239–250 | Cite as

On the sun's absolute disk-center and mean disk intensities, its limb darkening, and its `limb temperature' (λλ330 to 1099 nm)

  • Heinz Neckel


The coefficients A0 of the limb-darkening functions I(μ)/Icenter=P5(μ)=ΣAiμi (i=0,...5, μ=cos θ), published by Neckel and Labs (1994), and the corresponding disk-center intensities Icenter=I(μ=1), which were taken from the absolutely calibrated Kitt Peak FTS Atlas of the disk center (Brault et al., see Neckel and Labs, 1984, and Neckel 1999), are used to derive `limb intensities' Ilimb=I(μ=0)=A0Icenter. The corresponding `limb temperatures' Tlimb vary only slightly with wavelength; the mean value (≃4750 K) and the wavelength of maximum intensity (≃605 nm) conform to Wien's law (λmaxT=0.288 cm K). Further, Tlimb agrees closely with that temperature, which follows from Avrett's (2000) model of the photosphere for τ500≃0.006; for this layer the optical thickness along the line of sight is close to 1 (`the limb'; compare Unsöld, 1968). The slight variation of Tlimb with wavelength is presumably due to systematic errors in the Neckel and Labs intensity data: it corresponds almost precisely to the differences between their data and the more recent ones provided by, e.g., Burlov-Vasiljev, Gurtovenko, and Matvejev (1995), and Burlov-Vasiljev, Matvejev, and Vasiljeva (1998). Two simple correction functions (for λ≦550 nm and λ≧550 nm) are proposed, which apply to all Neckel and Labs intensity data (disk center and full disk, line spectrum and (quasi) continuum), and to the absolutely calibrated Kitt-Peak FTS Atlas (spectra of disk center and full disk) as well.


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  1. Avrett, E.: 2000, in A. N. Cox (ed.), Allen's Astrophysical Quantities, 4th ed., Springer-Verlag, New York, pp. 349-350.Google Scholar
  2. Burlov-Vasiljev, K. A., Gurtovenko, E. A., and Matvejev, Yu. B.: 1995, Solar Phys. 157, 51 (= BGM; N.B.: BGM + BMV = BGMV).Google Scholar
  3. Burlov-Vasiljev, K. A., Matvejev, Yu. B., and Vasiljeva, I. E.: 1998, Solar Phys. 177, 25 (= BMV; N.B.: BGM + BMV = BGMV).Google Scholar
  4. Kourganoff, V.: 1949, C. R. Acad. Sci. Paris 228, 2011 (Contr. Inst. Astrophys. Paris A, No. 46).Google Scholar
  5. Labs, D. and Neckel, H.: 1970, Solar Phys. 15, 79.Google Scholar
  6. Livingston, W. and Wallace, L.: 2003, Solar Phys. 212, 227 (this issue).Google Scholar
  7. Makarova, E. A., Roshchina, E. M., and Sarychev, A. P.: 1990, Kinematics Fiz. Nebesn. Tel. 6, 21.Google Scholar
  8. Minnaert, M.: 1953, in P. Kuiper (ed.), The Sun, The University of Chicago Press, Chicago, I11., p. 104.Google Scholar
  9. Neckel, H.: 1995, Solar Phys. 156, 7.Google Scholar
  10. Neckel, H.: 1996, Solar Phys. 167, 9.Google Scholar
  11. Neckel, H.: 1999, Solar Phys. 184, 421.Google Scholar
  12. Neckel, H. and Labs, D.: 1984, Solar Phys. 90, 205 (= NL84).Google Scholar
  13. Neckel, H. and Labs, D.: 1994, Solar Phys. 153, 91 (= NL94).Google Scholar
  14. Thuillier, G., Hersé, M., Simon, P. C., Labs, D., Mandel, H., Gillotay, D., and Foujols, T.: 1998, Solar Phys. 177, 41.Google Scholar
  15. Unsöld, A.: 1968, Physik der Sternatmosphären, 2nd ed. (Nachdruck), Springer-Verlag, Berlin, pp. 613-617.Google Scholar

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  • Heinz Neckel
    • 1
  1. 1.Hamburger SternwarteHamburgGermany

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