Multi-wavelength study of waves and solar atmospheric magneto-seismology

Abstract

Corona, the outermost layer of the solar atmosphere, is made up with very hot and taneous plasma material. The density and temperature structuring of this layer, is largely inhomogenous. Temperatures, at certain locations, can reach upto tens of million kelvin (MK). One of the key questions regarding the coronal physics is to identify the ubiquitous source(s) which can sustain this high temperature profile of the coronal plasma. One of the potential candidates in this case, is the family of magnetohydrodynamic (MHD) waves. These waves can propagate from the lower atmosphere to the solar corona and can partially (or fully) dissipate their energy to the surrounding coronal medium. In fact, different physical parameters such as the density, magnetic field and temperature of the host structure can also be inferred by studying the different properties of the propagating MHD wave.

This thesis is focused on examining the different properties of solar magnetohydro- dynamic (MHD) waves, specifically the slow magnetoacoustic mode (also known as

‘slow wave’), as seen with modern high resolution space based telescopes. Three key aspects: Generation, Propagation and Damping of these waves are studied rigorously in this thesis. A combination of high resolution spectroscopic and imaging data from the ‘Extreme-ultraviolet Imaging Spectrometer’, onboard Hinode and ‘Atmospheric Imaging Assembly’ (AIA), onboard Solar Dynamics Observatory (SDO), are used for the unambiguous detection of slow waves. Data from the ‘Helioseismic and Magnetic Imager’ (HMI) onboard SDO, and the ‘X-Ray Telescope’ (XRT) onboard Hinode, are also used to study the generation of these waves. Apart from the generation, we also

study the damping of these waves while they propagate through large coronal struc- tures, such as active region loops, polar plumes-interplumes etc. A large volume of

AIA imaging data have been analyzed to statistically determine the various properties

of the damping mechanisms. To supplement the observed results, we performed 3- D numerical simulations, along with the advanced ‘forward modelling’ technique and explained the observed wave properties.