Magnetohydrodynamic waves and coronal seismology: an overview of recent results

Magnetic fields permeate the entire solar atmosphere weaving an extremely complex pattern on both local and global scales. In order to understand the nature of this tangled web of magnetic fields, its magnetic skeleton, which forms the boundaries between topologically distinct flux domains, may be determined. The magnetic skeleton consists of null points, separatrix surfaces, spines and separators. The skeleton is often used to clearly visualize key elements of the magnetic configuration, but parts of the skeleton are also locations where currents and waves may collect and dissipate. In this review, the nature of the magnetic skeleton on both global and local scales, over solar cycle time scales, is explained. The behaviour of wave pulses in the vicinity of both nulls and separators is discussed and so too is the formation of current layers and reconnection at the same features. Each of these processes leads to heating of the solar atmosphere, but collectively do they provide enough heat, spread over a wide enough area, to explain the energy losses throughout the solar atmosphere? Here, we consider this question for the three different solar regions: active regions, open-field regions and the quiet Sun. We find that the heating of active regions and open-field regions is highly unlikely to be due to reconnection or wave dissipation at topological features, but it is possible that these may play a role in the heating of the quiet Sun. In active regions, the absence of a complex topology may play an important role in allowing large energies to build up and then, subsequently, be explosively released in the form of a solar flare. Additionally, knowledge of the intricate boundaries of open-field regions (which the magnetic skeleton provides) could be very important in determining the main acceleration mechanism(s) of the solar wind.

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“…[69]), resonant absorption (e.g. [70]) or mode coupling (for a review of wave dissipation mechanisms, see [71]). …”

Section: Discussionmentioning

confidence: 99%

Is magnetic topology important for heating the solar atmosphere?

Parnell

Stevenson

Threlfall

et al. 2015

Phil. Trans. R. Soc. A.

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“…As well as potentially being directly involved in heating, the detection of waves and oscillations has opened up the field of coronal seismology, potentially allowing parameters such as magnetic field strengths to be inferred (see [15] for a recent review).…”

Section: (A) Advances In Observationsmentioning

confidence: 99%

Recent advances in coronal heating

Moortel

Browning

2015

Phil. Trans. R. Soc. A.

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111

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The solar corona, the tenuous outer atmosphere of the Sun, is orders of magnitude hotter than the solar surface. This 'coronal heating problem' requires the identification of a heat source to balance losses due to thermal conduction, radiation and (in some locations) convection. The review papers in this Theo Murphy meeting issue present an overview of recent observational findings, large- and small-scale numerical modelling of physical processes occurring in the solar atmosphere and other aspects which may affect our understanding of the proposed heating mechanisms. At the same time, they also set out the directions and challenges which must be tackled by future research. In this brief introduction, we summarize some of the issues and themes which reoccur throughout this issue

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“…However, attention is increasingly turning to understanding the wave types and their behaviour in nonlinear three-dimensional media. In particular, the latest suite of space-and ground-based telescopes now regularly observes a wide range of wave modes, including Alfvénic waves and kink modes, which, as discussed by De Moortel and Nakariakov [22] may well play important roles in a wide range of different solar phenomena. Although extremely difficult to observe, waves will inevitably be present in almost all astrophysical objects, and so their existence and importance should not be forgotten when seeking explanations to observed astrophysical phenomena.…”

Section: Fundamental Plasma Processesmentioning

confidence: 99%

Astrophysical processes on the Sun

Parnell

2012

Phil. Trans. R. Soc. A.

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Over the past two decades, there have been a series of major solar space missions, namely Yohkoh, SOHO, TRACE, and in the past 5 years, STEREO, Hinode and SDO, studying various aspects of the Sun and providing images and spectroscopic data with amazing temporal, spatial and spectral resolution. Over the same period, the type and nature of numerical models in solar physics have been completely revolutionized as a result of widespread accessibility to parallel computers. These unprecedented advances on both observational and theoretical fronts have led to significant improvements in our understanding of many aspects of the Sun's behaviour and furthered our knowledge of plasma physics processes that govern solar and other astrophysical phenomena. In this Theme Issue, the current perspectives on the main astrophysical processes that shape our Sun are reviewed. In this Introduction, they are discussed briefly to help set the scene.

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Magnetohydrodynamic waves and coronal seismology: an overview of recent results

Cited by 331 publications

References 158 publications

Is magnetic topology important for heating the solar atmosphere?

Is magnetic topology important for heating the solar atmosphere?

Recent advances in coronal heating

Astrophysical processes on the Sun

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