Solar atmospheric seismology aims to determine physical parameters that are difficult to measure by direct means in magnetic and plasma structures. It is a remote diagnostics method that combines observations of oscillations and waves in magnetic structures, together with theoretical results from the analysis of oscillatory properties of given theoretical models. The philosophy behind this discipline is akin to that of Earth seismology, the sounding of the Earth interior using seismic waves, and helio-seismology, the acoustic diagnostic of the solar interior. It was first suggested by Uchida (1970) and Roberts et al. (1984), in the coronal context, and by Tandberg-Hanssen (1995) in the prominence context. The increase in the number and quality of high resolution observations in the 1990s has lead to the rapid development of solar atmospheric seismology. In the context of coronal loop oscillations, recent applications of this technique have allowed the estimation and/or restriction of parameters such as the magnetic field strength (Nakariakov and Ofman, 2001), the Alfvén speed in coronal loops (Zaqarashvili, 2003; Arregui et al., 2007a; Goossens et al., 2008), the transversal density structuring (Goossens et al., 2002; Verwichte et al., 2006) or the coronal density scale height (Andries et al., 2005; Verth et al., 2008).
The application of inversion techniques to prominence seismology is less developed. This is due to the complexity of these objects in comparison to, e.g., coronal loops. The recent refinement of theoretical models that incorporate the fine structuring of prominences and the high resolution observations of small amplitude oscillations have produced an increase in prominence seismology studies. Several techniques for the inversion of physical parameters have been developed that make use of observational estimates for quantities such as phase velocities, periods, damping times, and flow speeds. In general, the solution to the inverse problem cannot provide a single value for all the physical parameters of interest. However, important information about unknown physical quantities can be obtained using this method. The most relevant results of the MHD prominence seismology technique are here discussed.
The theoretical models decribed in Section 4 make use of different conceptual views of prominences, such as the string model, the slab model, and the thread model for their fine structure. Seismology efforts in the area have followed the same pattern. We describe them in increasing intricacy order, starting with a mechanical analogue (Section 6.1), followed by slab models (Section 6.2), and ending with the seismology of fine structure oscillations (Sections 6.3 to 6.6).
Living Rev. Solar Phys. 9, (2012), 2
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