Solar Physics: From the Deep Interior to the Hot Corona

  • Dermott J. Mullan
Conference paper
Part of the Lecture Notes in Physics book series (LNP, volume 556)


We present an overview of the thermal properties of the Sun from the hot interior to the hot corona. For pedagogical reasons, we confine the discussion to certain relevant solutions of the energy conservation equation. In the interior, quantitative information can be obtained by using a polytropic equation of state: internal temperatures obtained in this way are found to be reliable to about 10%, and we can obtain a good estimate of the depth of the convection zone. In the chromosphere, acoustic waves originating in the convection zone do work on the gas: as the gas heats up, the atomic energy levels of many elements (especially hydrogen) exert a strong thermostatic control so that the temperature is confined to a steady value in the range 5000-104 K. In long-lived coronal loops, a steady state balance between thermal conduction and radiative losses causes the temperature of the electrons to lie in the range (1-2) million K. Coronal ions are heated to greater temperatures than electrons. In flares, processes of heating and cooling are explicitly non-steady, and short-lived excursions to temperatures as high as 25 million K (or more) are observed in the largest flares.


Solar Wind Coronal Hole Solar Corona Solar Atmosphere Convection Zone 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    J. Christensen-Dalsgaard: Solar model with helium diffusion and settling (1999) (JCD): available online at website
  2. 2.
    D. J. Mullan and R. K. Ulrich: Ap. J. 331, 1013 (1988)CrossRefADSGoogle Scholar
  3. 3.
    D. J. Mullan: Ap. J. 337, 1017 (1989)CrossRefADSGoogle Scholar
  4. 4.
    G. Isaak et al.: in Advances in Helio-and Asteroseismology, ed. by J. Christensen-Dalsgaard (Reidel, Dordrecht 1986) pp. 53–57Google Scholar
  5. 5.
    M. Schwarzschild: Structure and Evolution of the Stars, (Princeton Univ. Press 1958)Google Scholar
  6. 6.
    F. W. Sears: Thermodynamics, 2nd edn. (Addison Wesley, Reading MA 1959), pp. 267–269Google Scholar
  7. 7.
    R. Kurucz: Rosseland mean opacities for solar composition (1992): available online at website
  8. 8.
    M. Hossain and D. J. Mullan: Ap. J. 416, 733 (1993)CrossRefADSGoogle Scholar
  9. 9.
    R. F. Stein and A. Nordlund: Ap. J. 499, 914 (1998)CrossRefADSGoogle Scholar
  10. 10.
    P. Foukal: Solar Astrophysics, (Wiley Interscience, New York 1990), p. 116Google Scholar
  11. 11.
    O. Namba and W. E. Diemel: Solar Phys. 7, 167 (1969)CrossRefADSGoogle Scholar
  12. 12.
    Lord Rayleigh,: Phil. Mag., Ser. 6, 32, 529 (1916)CrossRefGoogle Scholar
  13. 13.
    J. M. Beckers: Solar Phys. 3, 258 (1968)CrossRefADSGoogle Scholar
  14. 14.
    A. M. Title et al.: Ap. J. 336, 475 (1989)CrossRefADSGoogle Scholar
  15. 15.
    L. Biermann and R. Lust: in Stellar Atmospheres ed. by J. L. Greenstein (Univ. of Chicago Press, Chicago 1960) p. 272Google Scholar
  16. 16.
    Z. Musielak et al.: Ap. J. 423, 474 (1994)CrossRefADSGoogle Scholar
  17. 17.
    L. Spitzer: Physics of Fully Ionized Gases, (Interscience, New York 1962), p. 128Google Scholar
  18. 18.
    D. J. McComas et al.: Geophys. Res. Lett. 25, 1 (1998): the figure is available online at website swoops.html CrossRefADSGoogle Scholar
  19. 19.
    E. N. Parker: Interplanetary Dynamical Processes, (Interscience, New York 1963), p. 75zbMATHGoogle Scholar
  20. 20.
    R. Esser et al.: Ap. J. Lett. 510, L67 (1999)CrossRefADSGoogle Scholar
  21. 21.
    I. Cuseri et al.: Ap. J. 514, 989 (1999)CrossRefADSGoogle Scholar
  22. 22.
    S. R. Cranmer et al.: Ap. J. 518, 937 (1999)CrossRefADSGoogle Scholar
  23. 23.
    D. J. Mullan and O. I. Yakovlev: Irish Astron. J. 22, 119 (1995)ADSGoogle Scholar
  24. 24.
    O. I. Yakovlev and D. J. Mullan: Irish Astron. J. 23, 7 (1996)ADSGoogle Scholar
  25. 25.
    J. T. Schmeltz et al.: Ap. J. 434, 786 (1994)CrossRefADSGoogle Scholar
  26. 26.
    U. Feldman et al.: Ap. J. 460, 1034 (1996)CrossRefADSGoogle Scholar
  27. 27.
    D. S. Spicer and J. C. Brown: in The Sun as a Star ed. by S. Jordan (NASA SP-450 1982), pp. 413–471Google Scholar
  28. 28.
    D. S. Spicer: in: Activity in Red Dwarf Stars ed. by P. B. Byrne and M. Rodono (Reidel, Dordrecht 1982), p. 560Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • Dermott J. Mullan
    • 1
  1. 1.Bartol Research InstituteUniversity of DelawareNewarkUSA

Personalised recommendations