Abstract
The ignition of coronal shock waves by flares is investigated. It is assumed that an explosive expansion of the source region caused by impulsive heating generates a fast-mode MHD blast wave which subsequently transforms into a shock wave. The solutions of 1-D MHD equations for the flaring region and for the external region are matched at their boundary. The obtained results show under what conditions flares can ignite shock waves that excite the metric type II bursts. The heat input rate per unit mass has to be sufficiently high and the preflare value of the plasma parameter β in the flaring region has to be larger than β0 crit. The critical values depend on the flare dimensions and impulsiveness. Larger and more impulsive flares are more effective in generating type II bursts. Shock waves of a higher Mach number require a higher preflare value of β and a more powerful heating per unit mass. The results demonstrate why only a small fraction of flares is associated with type II bursts and why the association rate increases with the flare importance.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Aurass, H., Vršnak, B., Hofmann, A., and Ruždjak, V.: 1999, Solar Phys. 190, 267.
Cliver, E. W., Webb, D. F., and Howard, R. A.: 1999, Solar Phys. 187, 89.
Dennis, B. R. and Schwartz, R. A.: 1989, Solar Phys. 121, 75.
Drago, F. G. and Tagliaferri, G. L.: 1967, Osservatorio Astrofisico Arcetri, Contributo
Dulk, G. A. and McLean, D. J.: 1978, Solar Phys. 57, 279.
Harvey, G. A.: 1965, J. Geophys. Res. 70, 13.
Karlický, M. and Odstrčil, D.: 1994, Solar Phys. 155, 171.
Klassen, A., Aurass, H., Klein, K.-L., Hofmann, A., and Mann, G.: 1999, Astron. Astrophys. 343, 287.
Kosugi, T.: 1994, in S. Enome and T. Hirayama (eds.) Nobeyama Radio. Obs. Report 360, 11.
Moreton, G. E.: 1960, Astrophys. J. 65, 494.
Nelson, G. J. and Melrose, D. B.: 1985, in D. J. McLean and N. R. Labrum (eds.), Solar Radiophysics, Cambridge University Press, Cambridge, p. 333.
Pearson, D. H., Nelson, R., Kojoian, G., and Seal, J.: 1989, Astrophys.J. 336, 1050.
Priest, E. R.: 1982, Solar Magnetohydrodynamics, D. Reidel Publ. Co., Dordrecht, The Netherlands.
Priest, E. R. and Forbes, T. G.: 1986, J. Geophys. Res. 91, 5579.
Smith, S. F. and Harvey, K. L.: 1971, in C. J. Macris (ed.), Physics of Solar Corona, D. Reidel Publ. Co., Dordrecht, The Netherlands, p. 156.
Strong, K. T., Benz, A. O., Dennis, B. R., Leibacher, J. W., Mewe, R., Poland, A. I., Schrijver, J., Simnett, G., Smith, J. B. and Sylwester, J.: 1984, Solar Phys. 91, 325.
švestka, Z. and Fritzová-švestková L.: 1974, Solar Phys. 36, 417.
Tandberg-Hanssen, E., Martin, S. F., and Hansen, R. T.: 1980, Solar Phys. 65, 357.
Uchida, Y.: 1974, Solar Phys. 39, 431.
Vršnak, B.: 1989, Solar Phys. 120, 79.
Vršnak, B.: 2000, in A. Hanslmeier and M. Messerotti (eds.), The Dynamic Sun, Astrophysics and Space Science Library, Kluwer Academic Publishers, Dordrecht, The Netherlands (in press)
Vršnak, B. and Lulić, S.: 2000, Solar Phys. 196, 157 (this issue).
Vršnak, B., Ruždjak, V., Zlobec, P., and Aurass, H.: 1995, Solar Phys. 158, 331.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Vršnak, B., Lulić, S. Formation of coronal MHD shock waves – II. The Pressure Pulse Mechanism. Solar Physics 196, 181–197 (2000). https://doi.org/10.1023/A:1005288310697
Issue Date:
DOI: https://doi.org/10.1023/A:1005288310697