Unravelling the components of a multi-thermal coronal loop using magnetohydrodynamic seismology

Abstract

Coronal loops, constituting the basic building blocks of the active Sun, serve as primary targets to help understand the mechanisms responsible for maintaining multi-million Kelvin temperatures in the solar and stellar coronae. Despite significant advances in observations and theory, our knowledge on the fundamental properties of these structures is limited. Here, we present unprecedented observations of accelerating slow magnetoacoustic waves along a coronal loop that show differential propagation speeds in two distinct temperature channels, revealing the multi-stranded and multi-thermal nature of the loop. Utilizing the observed speeds and employing nonlinear force-free magnetic field extrapolations, we derive the actual temperature variation along the loop in both channels, and thus are able to resolve two individual components of the multi-thermal loop for the first time. The obtained positive temperature gradients indicate uniform heating along the loop, rather than isolated footpoint heating.

arXiv commentaccepted for publication in ApJ

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• The polytropic index of solar coronal plasma in sunspot fan loops and its temperature dependence
• Statistical Signatures of Nanoflare Activity. I. Monte Carlo Simulations and Parameter-space Exploration
• Novel data analysis techniques in coronal seismology
• A new look at the frequency-dependent damping of slow-mode waves in the solar corona
• Coronal seismology by slow waves in non-adiabatic conditions
• Observational and numerical characterization of a recurrent arc-shaped front propagating along a coronal fan