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A&A 372, L53-L56 (2001)
DOI: 10.1051/0004-6361:20010607

Determination of the coronal magnetic field by coronal loop oscillations

V. M. Nakariakov¹ and L. Ofman<sup>2

1</sup>  Physics Department, University of Warwick, Coventry CV4 7AL, UK
²  CUA/NASA Goddard Space Flight Center, 682, Greenbelt, MD 20771, USA
    e-mail: leon.ofman@gsfc.nasa.gov

(Received 30 October 2000 / Accepted 26 April 2001)

Abstract
We develop a new method for the determination of the absolute value of the magnetic field strength in coronal closed magnetic structures, based on the analysis of flare-generated oscillations of coronal loops. Interpretation of the oscillations observed in terms of global standing kink waves allows to connect the period of the oscillations and the loops length with the magnetic field strength in the loops. For loop oscillations observed with TRACE on 14th July 1998 and 4th July 1999, we estimate the magnetic field strength as 4-30 G. Using TRACE 171 Åand 195 Åimages of the loop, taken on 4th July 1999 to determine the plasma density, we estimate the magnetic field in the loop as G. Improved diagnostic of the loop length, the oscillation period, and the plasma density in the loop will significantly improve the method's precision.

Key words: magnetohydrodynamics (MHD) -- waves -- Sun: corona -- Sun: activity -- Sun: oscillations -- Sun: UV radiation

Offprint request: V. M. Nakariakov, valery@astro.warwick.ac.uk

© ESO 2001

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