Research Topics
Seismology of the Solar Corona
Seismology refers to the process of deriving the physical conditions of a medium by analysing properties of the oscillations or the waves travelling through the medium. In this sense, Helioseismology became an efficient tool to probe the internal structure of the Sun, while thanks to space-based high-resolution observations, which provided with strong evidence about the presence of oscillations and waves in coronal magnetic structures, Solar Atmospheric Seismology became also a reality. MHD waves and oscillations provide with an indirect path to determine physical parameters [coronal magnetic field, transport coefficients (viscosity, resistivity, thermal conductivity, etc.), heating function, filling factors, inhomogeneity scale] of the solar corona. Therefore, MHD seismology is a method of remote diagnostics of plasma structures combining observations of oscillatory motions with an interpretation in terms of MHD waves.
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Behaviour of Solar Activity
Solar activity is produced by the emergence of magnetic flux through the photosphere forming active regions which include sunspots. The most characteristic feature of solar activity is its basic 11-year cycle (or 22-year magnetic cycle) and, although models with periodic solutions which reproduce the essential features of the solar cycle have been constructed, the sunspot cycle is basically aperiodic displaying intervals (Maunder minimum, Spörer minimum) with very low solar activity, which suggests that the solar dynamo behaves like a non-linear oscillator in a regime where chaos has developed. The chaotic behaviour of the solar cycle has been investigated as well as the North-South asymmetry of sunspots distribution. On the other hand, short-term periodicities in solar flares were also discovered which have been interpreted in terms of periodic emergence of magnetic flux triggered by instabilities of Rossby waves in the tachocline.
Waves and Instabilities in prominences
Prominences are intriguing, but poorly understood, magnetic structures of the solar corona. The dynamics of solar prominences Prominence oscillatios are usually interpreted in terms of MHD waveshas been the subject of a large number of studies, and of particular interest is the study of prominence oscillations. Ground- and space-based observations have confirmed the presence of oscillatory motions in prominences and they have been interpreted in terms of magnetohydrodynamic (MHD) waves. This interpretation opens the door to perform prominence seismology, whose main aim is to determine physical parameters in magnetic and plasma structures (prominences) that are difficult to measure by direct means. On the other hand, the dynamics of prominence is very complex and suggests that different MHD instabilities are taking place in a continuous way.