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MHD Seismology of the Solar Corona with SOHO and TRACE

Published online by Cambridge University Press:  13 May 2016

V. M. Nakariakov
V. M. Nakariakov*
Affiliation:
Physics Department, University of Warwick, Coventry CV4 7AL, UK email: [email protected]

Abstract

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Recent discoveries of MHD wave motions in the solar corona done with EUV imaging telescopes onboard SOHO and TRACE provide an observational basis for the MHD seismology of the corona. Measuring the properties of MHD waves and oscillations (periods, wavelengths, amplitudes, temporal and spatial signatures), combined with theoretical modeling of the wave phenomena, allow us to determine values of the mean parameters of the corona (the magnetic field strength, transport coefficients, etc.). As an example, we consider post-flare decaying oscillations of loops, observed with TRACE (14th July 1998 at 12:55 UT). An analysis of the oscillations shows that they are quasi-harmonic, with a period of about 265 s, and quickly decaying with the decay time of about 14.5 min. The period of oscillations allows us to determine the Alfvén speed in the oscillating loop about 770 km/s. This value can be used for deduction of the value of the magnetic field in the loop (giving 10-30 G). The decay time, in the assumption that the decay is caused by viscous (or resistive) dissipation, gives us the Reynolds number of 105.3-6.1 (or the Lundquist number of 105.0-5.8).

Type
Session IV: Structure and Dynamics of the Transiton Region and Corona
Information
Symposium - International Astronomical Union , Volume 203: Recent Insights into the Physics of the Sun and Heliosphere: Highlights from Soho and Other Space Missions , 2001 , pp. 353 - 355
Copyright
Copyright © Astronomical Society of the Pacific 2001 

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