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Astron. Astrophys. 353, 786-796 (2000)

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Coronal plasmoid dynamics

II. The nonstationary fine structure

A.N. Zhukov 1, I.S. Veselovsky 1, S. Koutchmy  *  2 and C. Delannée 3

1 Institute of Nuclear Physics, Moscow State University, 119899 Moscow, Russia
2 Institut d'Astrophysique, CNRS, 98 bis Boulevard Arago, 75014 Paris, France
3 Institut d'Astrophysique Spatiale, Université Paris XI, Bât. 121, 91405 Orsay, France

Received 22 July 1999 / Accepted 10 November 1999

Abstract

We analyze the non-uniform motion of a white light coronal plasmoid of 1.5 Mm in diameter, which has been followed at the prime focus of the Canada-France-Hawaii Telescope (CFHT) during the July 11, 1991 total solar eclipse. Two possibilities are considered to explain the acceleration of the plasmoid by the magnetic force: large amplitude oscillations and the rotation of the plasmoid magnetic dipole about the external inhomogeneous magnetic field vector. We then describe for the first time the fine structure of the plasmoid, its splitting and its interaction with the surrounding thread-like coronal structures. The smallest-scale inhomogeneities (knots inside the plasmoid) have a characteristic length of about 400 km. The observed complex behaviour of these plasma objects leads us to conclude that existing models of mass supply to the corona by expanding plasmoids and their input into the process of the solar wind acceleration seem to be oversimplified, mainly because the fine structure and the turbulent intermixing have not been realistically taken into account. We also conclude on the importance of dynamical processes at the smallest scales coronal structures when the heating problem is considered.

Key words: Sun: corona – Sun: magnetic fields

* Associated with the Pierre et Marie Curie University, Paris VI

Send offprint requests to: S. Koutchmy

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© European Southern Observatory (ESO) 2000

Online publication: December 17, 1999
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