Hostname: page-component-7bb8b95d7b-l4ctd Total loading time: 0 Render date: 2024-10-04T18:34:39.788Z Has data issue: false hasContentIssue false
  • English
  • Français

Models of Spots and Flares

Published online by Cambridge University Press:  12 April 2016

D.J. Mullan
D.J. Mullan*
Affiliation:
Bartol Research Foundation, University of Delaware Newark, Delaware 19711 USA

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

MHD effects in stars are seen in their most spectacular form in the processes which are typical of flares. At first sight, it appears that the phenomena of dark spots (whose long lifetimes give an impression of quasi-equilibrium) are inevitably less interesting. However, this is not necessarily true. Laboratory experiments in recent years have shown that there are many more ways to drive a plasma out of equilibrium than to preserve equilibrium. In that sense, then, it is perhaps “easier to understand” why flares should occur in a stellar atmosphere (where convective jostling of field lines creates potential for driving a large number of instabilities) than why a long-lived feature such as a dark spot should persist. Various instabilities which may contribute to flares are discussed by Priest and Spicer (this volume). Here, we summarize work on the equilibrium structure of cool spots in the sun and stars. Since spots involve complex interactions between convective flows and magnetic fields, we need to refer to observations for help in identifying the dominant processes which should enter into the modelling. This summary therefore begins by discussing certain relevant properties of spots in the solar atmosphere.

Type
Session IV: Theoretical Aspects
Information
International Astronomical Union Colloquium , Volume 71: Activity in Red-Dwarf Stars , 1983 , pp. 527 - 543
Copyright
Copyright © Reidel 1983

References

REFERENCES

Baum, P.J. and Bratenahl, A.: 1980, Solar Phys. 67, 245.CrossRefGoogle Scholar
Beckers, J.: 1977, Ap. J. 213, 900.CrossRefGoogle Scholar
Caton, D.B.: 1981, Publ. Obs. Appalachian St. Univ., Vol.1, part 2.Google Scholar
Cowling, T.G.: 1976, Mon. Not. Roy. Astron. Soc. 177, 409.CrossRefGoogle Scholar
Cox, A.N. et al.: 1981, Ap. J. Letters, 245, L37.Google Scholar
DeJager, C.: 1968, in Structure and Evolution of Active Regions, ed. Kiepenheuer, K. (Dordrecht: Reidei), p. 480.CrossRefGoogle Scholar
Frazier, E.N.: 1977, Astron. Ap. 64, 355.Google Scholar
Hartmann, L. and Rosner, R.: 1979, Ap. J. 230, 802.CrossRefGoogle Scholar
Low, B.C.: 1980, Solar Phys. 67, 57.CrossRefGoogle Scholar
Meyer, F. et al.: 1974, Mon. Not. Roy. Astron. Soc. 169, 35.Google Scholar
Meyer, F. et al.: 1977, Mon. Not. Roy. Astron. Soc. 179, 741.CrossRefGoogle Scholar
Moore, R.L.: 1981, Space Sei. Rev. 28, 387.CrossRefGoogle Scholar
Mullan, D.J.: 1973, Ap. J. 186, 1059.CrossRefGoogle Scholar
Mullan, D.J.: 1974a, Ap. J. 187, 621.Google Scholar
Mullan, D.J.: 1974b, Ap. J. 192, 149.CrossRefGoogle Scholar
Mullan, D.J.: 1975a, Astron. Ap. 40, 41.Google Scholar
Mullan, D.J.: 1975b, Ap. J. 200, 641.Google Scholar
Mullan, D.J.: 1979, Irish AJ 14, 73.Google Scholar
Mullan, D.J.: 1981, Solar Phys. 70, 381 CrossRefGoogle Scholar
Orrall, F.Q.: 1981, Space Sci. Rev. 28, 423.CrossRefGoogle Scholar
Pardon, L. et al.: 1979, Sol. Phys. 63, 247.CrossRefGoogle Scholar
Parker, E.N.: 1979, Ap. J. 230, 905.CrossRefGoogle Scholar
Piddington, J.H.: 1973, Solar Phys. 31, 229.CrossRefGoogle Scholar
Piddington, J.H.: 1976, Ap. Space Sci. 40, 73.CrossRefGoogle Scholar
Rucinski, S.: 1979, Acta Astron. 29, 203.Google Scholar
Schatten, K.H.: 1981, Ap. J. 247, L139.Google Scholar
Spitzer, L.: 1962, Physics of Fully Ionized Gases (Interscience).Google Scholar
Spruit, H.C.: 1977, dissertation, Utrecht.Google Scholar
Spruit, H.C.: 1982, Astron. Ap. 108, 348.Google Scholar
Staude, J.: 1978, Bull. Aston. Inst. Czechoslov. 29, 71.Google Scholar
Stellmacher, A. and Weihr, E.: 1976, Astron. Ap. 47, 479.Google Scholar
Stenflo, J.O.: 1973, Solar Phys. 32, 41.Google Scholar
Thomas, J.H.: 1978, Ap. J. 225, 275.CrossRefGoogle Scholar
Vrabec, D.: 1974, in IAU Symo. 56, 201.Google Scholar
Willson, R.C. et al.: 1981, Science 211, 700.CrossRefGoogle Scholar
Zhugzhda, Y.: 1982, Solar Phys. 81, 245.Google Scholar
Zwaan, C.: 1978, Solar Phys. 60, 213.Google Scholar