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Astron. Astrophys. 337, L9-L12 (1998)
Letter to the Editor
On a source of Alfvén waves heating the solar corona
Alexander Ruzmaikin 1 and
Mitchell A. Berger 2
1 Jet Propulsion Laboratory, California Institute of
Technology, Pasadena, CA 91109, USA (e-mail:
aruzmaikin@jplsp.jpl.nasa.gov)
2 Department of Mathematics, University College London,
London, WC1E 6BT, UK (e-mail: mberger@math.ucl.ac.uk)
Received 29 June 1998 / Accepted 14 July 1998
Abstract
Studies of the origin of coronal heating and acceleration of the solar wind invoke high-frequency Alfvén waves. Here we suggest a source for such waves associated with twisted magnetic loops emerging on the solar surface and reconnecting with the open field. We identify the loops with the ephemeral regions (small-scale bipoles) observed by ground-based instruments and by SOHO. To characterize the loops we employ the concept of a minimum energy state for topologically complex fields. Emerging loops release energy relaxing to the minimum state. Relaxation along the minimum state-due to a competition between footpoint twisting by photospheric motions and reconnections inside the loops- releases blinks of energy into the solar atmosphere. We estimate the power released and the range of wave frequencies.
Key words: Solar corona heating: magnetic fields
Send offprint requests to: A. Ruzmaikin
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Contents
- 1. Introduction
- 2. Minimum energy of topologically complex magnetic fields
- 3. Relaxation along the minimum state: the source of "nanoflares"
- 4. Generation of waves by reconnections of braided loops with open field lines
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998
Online publication: August 6, 1998
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