Abstract
In previous publications (Keppens et al.: 2002, Astrophys. J. 569, L121; Goedbloed et al.: 2004a, Phys. Plasmas 11, 28), we have demonstrated that stationary rotation of magnetized plasma about a compact central object permits an enormous number of different MHD instabilities, with the well-known magneto-rotational instability (Velikhov, E. P.: 1959, Soviet Phys.–JETP Lett. 36, 995; Chandrasekhar, S.: 1960, Proc. Natl. Acad. Sci. U.S.A. 46, 253; Balbus, S. A. and Hawley, J. F.: 1991, Astrophys. J. 376, 214) as just one of them. We here concentrate on the new instabilities found that are driven by transonic transitions of the poloidal flow. A particularly promising class of instabilities, from the point of view of MHD turbulence in accretion disks, is the class of trans-slow Alfv’en continuum modes, that occur when the poloidal flow exceeds a critical value of the slow magnetosonic speed. When this happens, virtually every magnetic/flow surface of the disk becomes unstable with respect to highly localized modes of the continuous spectrum. The mode structures rotate, in turn, about the rotating disk. These structures lock and become explosively unstable when the mass of the central object is increased beyond a certain critical value. Their growth rates then become huge, of the order of the Alfv’en transit time. These instabilities appear to have all requisite properties to facilitate accretion flows across magnetic surfaces and jet formation.
Similar content being viewed by others
References
Balbus, S. A. and Hawley, J. F.: 1991, Astrophys. J. 376, 214.
Beliën, A. J. C., Botchev, M. A., Goedbloed, J. P., van der Holst, B., and Keppens, R.: 2002, J. Comp. Phys. 182, 91.
Casse, F. and Keppens, R.: 2002, Astrophys. J. 581, 988.
Casse, F. and Keppens, R.: 2004, Astrophys. J. 601, 90.
Chandrasekhar, S.: 1960, Proc. Natl. Acad. Sci. U.S.A. 46, 253.
Frank, J., King, A., and Raine, D.: 2002, Accretion Power in Astrophysics, 3rd edn., Cambridge University Press, Cambridge.
Goedbloed, J. P.: 2004, Phys. Plasmas 11, L81.
Goedbloed, J. P., Beliën, A. J. C., van der Holst, B., and Keppens, R.: 2004a, Phys. Plasmas 11, 28.
Goedbloed, J. P., Beliën, A. J. C., van der Holst, B., and Keppens, R.: 2004b, Phys. Plasmas 11, 4332.
Goedbloed, J. P. and Poedts, S.: 2004, Principles of Magnetohydrodynamics, with Applications to Laboratory and Astrophysical Plasmas, Cambridge University Press, Cambridge, 2004.http://www.titles.cambridge.org/catalogue.asp?isbn=0521626072
Keppens, R., Casse, F., and Goedbloed, J. P.: 2002, Astrophys. J. 569, L121.
Tóth, G.: 1996, Astrophys. Lett. Comm. 34, 245.http://www.phys.uu.nl/toth/
Velikhov, E. P.: 1959, Soviet Phys.–JETP Lett. 36, 995.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Goedbloed, H., Keppens, R. MHD Spectroscopy of Transonic Flows. Space Sci Rev 121, 55–63 (2005). https://doi.org/10.1007/s11214-006-2729-0
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11214-006-2729-0