Magnetohydrodynamics of the Sun

Priest, E. R.

doi:10.1017/cbo9781139020732

Cited by 549 publications

(392 citation statements)

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“…We obtain the mean value 30 km for the flux tube diameter, 230 km for the average distance between flux tubes, and 1.3 kG for the mean flux tube field strength. This is similar to the minimum flux tube width of 10 km estimated by Priest [] on theoretical grounds.…”

Section: Resultssupporting

confidence: 89%

Milne‐Eddington inversion for unresolved magnetic structures in the quiet Sun photosphere

Bommier

2016

JGR Space Physics

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This paper is first devoted to present our method for modeling unresolved magnetic structures in the Milne‐Eddington inversion of spectropolarimetric data. The related definitions and other approaches and different used inversion algorithms are recalled for comparison. In a second part, we apply our method to quiet Sun data outside active regions. We obtain the quiet Sun photospheric magnetic field as composed of unresolved opening and connected magnetic flux tubes, which form a loop carpet of field lines. We then analyze the spatial correlation, which we also observed for the magnetic field vector, in terms of flux tube diameter, distance, and field strength. We find that different observations with the Zurich imaging polarimeter and THEMIS polarimeter mounted on the THEMIS telescope give very close results, and we add results also very close derived from HINODE/Solar Optical Telescope/spectropolarimeter observations analyzed with the same method. We obtain a mean flux tube diameter of 30 km, a mean flux tube distance of 230 km, and a mean flux tube magnetic field of 1.3 kG.

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Section: Resultssupporting

confidence: 89%

Milne‐Eddington inversion for unresolved magnetic structures in the quiet Sun photosphere

Bommier

2016

JGR Space Physics

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“…The "Sun in time" review of Güdel (2007) also contains much useful background. Various aspects of the Solar wind and Solar massloss specifically are reviewed in Bruno and Carbone (2013), Ofman (2010), Marsch (2006), Owens and Forsyth (2013), as well as in the textbooks by Priest (2014) and Aschwanden (2005). We have drawn on these for the brief summary below.…”

Section: Mass Lossmentioning

confidence: 99%

Magnetism, dynamo action and the solar-stellar connection

Brun

Browning

2017

Living Rev Sol Phys

243

182

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The Sun and other stars are magnetic: magnetism pervades their interiors and affects their evolution in a variety of ways. In the Sun, both the fields themselves and their influence on other phenomena can be uncovered in exquisite detail, but these observations sample only a moment in a single star's life. By turning to observations of other stars, and to theory and simulation, we may infer other aspects of the magnetism-e.g., its dependence on stellar age, mass, or rotation rate-that would be invisible from close study of the Sun alone. Here, we review observations and theory of magnetism in the Sun and other stars, with a partial focus on the "Solar-stellar connection": i.e., ways in which studies of other stars have influenced our understanding of the Sun and vice versa. We briefly review techniques by which magnetic fields can be measured (or their presence otherwise inferred) in stars, and then highlight some key observational findings uncovered by such measurements, focusing (in many cases) on those that offer particularly direct constraints on theories of how the fields are built and maintained. We turn then to a discussion of how the fields arise in different objects: first, we summarize some essential elements of convection and dynamo theory, including a very brief discussion of mean-field theory and related concepts. Next we turn to simulations of convection and magnetism in stellar interiors, highlighting both some peculiarities of field generation in different types of stars and some unifying physical processes that likely influence dynamo action in general. We conclude with a brief

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“…The physics of the radiation imply that it is most effective only at temperatures below about 0.1 MK. The energy flux through heat conduction, q, is highly dependent on temperature, being most efficient at high temperatures [11]. Consequently, in a model with heating being constant in space, the energy input locally in the transition region will play a minor role and the radiative losses there will be balanced mainly by the heat conduction back from the corona [55].…”

Section: (F) Heating Heat Conduction and Radiationmentioning

confidence: 99%

What can large-scale magnetohydrodynamic numerical experiments tell us about coronal heating?

Peter

2015

Phil. Trans. R. Soc. A.

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The upper atmosphere of the Sun is governed by the complex structure of the magnetic field. This controls the heating of the coronal plasma to over a million kelvin. Numerical experiments in the form of threedimensional magnetohydrodynamic simulations are used to investigate the intimate interaction between magnetic field and plasma. These models allow one to synthesize the coronal emission just as it would be observed by real solar instrumentation. Largescale models encompassing a whole active region form evolving coronal loops with properties similar to those seen in extreme ultraviolet light from the Sun, and reproduce a number of average observed quantities. This suggests that the spatial and temporal distributions of the heating as well as the energy distribution of individual heat deposition events in the model are a good representation of the real Sun. This provides evidence that the braiding of fieldlines through magneto-convective motions in the photosphere is a good concept to heat the upper atmosphere of the Sun.

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Magnetohydrodynamics of the Sun

Cited by 549 publications

References 0 publications

Milne‐Eddington inversion for unresolved magnetic structures in the quiet Sun photosphere

Milne‐Eddington inversion for unresolved magnetic structures in the quiet Sun photosphere

Magnetism, dynamo action and the solar-stellar connection

What can large-scale magnetohydrodynamic numerical experiments tell us about coronal heating?

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