One of the most prominent features seen in images of the solar corona by EUV telescopes are the elegant arches of glowing plasma that trace magnetic field lines through the corona. Typically, these…

This federal contract award, valued at $599,775.37, was granted by the National Aeronautics and Space Administration (NASA) to the Regents of the University of Colorado, doing business as the University of Colorado (CU). The award is not associated with a set-aside designation.

The contract aims to advance the understanding of magnetic field dynamics and oscillations in the solar corona, which are believed to be linked to the occurrence of solar flares and coronal mass ejections. To achieve this, the research team at CU will conduct analytical calculations and numerical simulations to identify seismic diagnostics that can reveal the nature and dimensionality of the observed wave activity in the solar corona. Additionally, the team will analyze imagery from NASA's Atmospheric Imaging Assembly (AIA) and Solar Terrestrial Relations Observatory (STEREO) to search for the identified seismic signatures and assess their potential for monitoring the coronal magnetic field and predicting explosive solar events. This work is expected to contribute to the development of improved space weather forecasting capabilities.

One of the most prominent features seen in images of the solar corona by EUV telescopes are the elegant arches of glowing plasma that trace magnetic field lines through the corona. Typically, these loops are preferentially illuminated segments of a larger structure comprised of an arcade of arched field lines. These arcades occasionally fulminate in flares or coronal mass ejections (CMES), and the energy driving such eruptions comes from the magnetic energy of the corona itself. Thus, the ability to probe and assess the field strength and topology of the magnetic field prior to detonation is likely a necessity for predicting such behavior. Unfortunately, IT has proven challenging to spectroscopically measure the magnetic field within the corona. Our goal here is to circumvent this obstacle, by laying the ground work required to measure the corona's magnetic field seismically. Coronal loops are often observed to shimmer and undulate, sometimes in clear response to nearby solar flares but often without an obvious initiating event. A flurry of observational and theoretical effort has been devoted to the explanation and exploitation of these oscillations. However, before seismic techniques can be fruitfully applied, we must have a firm grasp on the nature of the waves and the geometry of the waveguide. The commonly accepted viewpoint is that each visible loop oscillates as an independent entity and acts as a separate 1D wave cavity for MHD kink waves. We believe that this generally accepted model for the wave cavity is fundamentally wrong. In particular, we argue that the entire 3D magnetic arcade in which the bright loops reside participates in the oscillation. Thus, the true wave cavity is larger than the individual loop and inherently multi-dimensional. Our ultimate scientific goal is to develop seismic diagnostics that can be used to predict the likelihood of explosive events such as flares and CMES. Since the magnetic energy in the corona feeds the explosive instability, achieving our goal will probably require the ability to regularly measure the magnetic field (which to date has proven elusive). The first step to acquiring this capability is to understand the nature of the observed oscillations and their waveguide. Thus, we suggest that detailed answers to the following questions must be gleaned: (1) what type of MHD wave mode produces the observed oscillations? Are they alfvenic? Are they fast magnetic-pressure waves? Or are they a coupling of these two possibilities? (2) what are the dimensionality, geometry, and spatial extent of the wave cavity in which the MHD waves reside? Where do the waves originate, propagate, and reflect? (3) are there certain classes of waves or oscillations that can be used to seismically monitor the status of an arcade prior to eruptive events? Here we propose to answer these fundamental questions through two tasks, one comprised of theory and numerical simulation and the other involving direct analysis of coronal imagery. For task a we will perform analytic calculations and numerical simulations of the propagation of MHD waves within the 3D waveguides that naturally form within magnetic arcades. We will compute the eigenfunctions and eigenfrequencies of the resonant MHD waves and explore a variety of driving mechanisms, including broadband stochastic driving at the magnetic fields footpoints and large impulsive driving events such as flares. The primary goal will be to identify seismic diagnostics that indicate the nature of the observed waves and dimensionality of the wave cavity. For task B, using coronal imagery from AIA and stereo, we will search for the identified diagnostics and apply seismic techniques that exploit information gleaned from multiple loops within an arcade. In addition we will assay the suitability of different classes of loop oscillations for use in monitoring the coronas magnetic field and in prediction of flares and CMES.