Alfvénic waves in the inhomogeneous solar atmosphere

Morton, R. J.; Sharma, Rahul; Tajfirouze, E.; H., Miriyala,

doi:10.1007/s41614-023-00118-3

Cited by 20 publications

(8 citation statements)

References 250 publications

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“…Indeed, transverse waves are found to exhibit a significant amount of energy flux in the solar chromosphere (De Pontieu et al 2007;Srivastava et al 2017) and corona (Hassler et al 1990;Banerjee et al 1998Banerjee et al , 2009McIntosh et al 2011;Hahn & Savin 2013), although whether it is sufficient for the coronal heating is controversial (Tomczyk et al 2007;Okamoto & De Pontieu 2011;Thurgood et al 2014). In considering the wave propagation into the corona, we often assume that the horizontal random buffeting motion of photospheric MCs (Berger & Title 1996;Berger et al 1998;van Ballegooijen et al 1998;Nisenson et al 2003;Chitta et al 2012) is responsible for the wave generation (see the review by Morton et al 2023).…”

Section: Introductionmentioning

confidence: 99%

Magnetic Tornado Properties: A Substantial Contribution to the Solar Coronal Heating via Efficient Energy Transfer

Kuniyoshi

Shoda

Iijima

et al. 2023

ApJ

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In solving the solar coronal heating problem, it is crucial to comprehend the mechanisms by which energy is conveyed from the photosphere to the corona. Recently, magnetic tornadoes, characterized as coherent, rotating magnetic-field structures extending from the photosphere to the corona, have drawn growing interest as a possible means of efficient energy transfer. Despite its acknowledged importance, the underlying physics of magnetic tornadoes remains elusive. In this study, we conduct a three-dimensional radiative magnetohydrodynamic simulation that encompasses the upper convective layer and extends into the corona, with a view to investigating how magnetic tornadoes are generated and efficiently transfer energy into the corona. We find that a single event of magnetic flux concentration merger on the photosphere gives rise to the formation of a single magnetic tornado. The Poynting flux transferred into the corona is found to be four times greater in the presence of the magnetic tornado, as compared to its absence. This increase is attributed to a reduction in energy loss in the chromosphere, resulting from the weakened magnetic-energy cascade. Based on an evaluation of the fraction of the merging events, our results suggest that magnetic tornadoes contribute approximately 50% of the Poynting flux into the corona in regions where the coronal magnetic-field strength is 10 G. Potentially, the contribution could be even greater in areas with a stronger coronal magnetic field.

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Section: Introductionmentioning

confidence: 99%

Magnetic Tornado Properties: A Substantial Contribution to the Solar Coronal Heating via Efficient Energy Transfer

Kuniyoshi

Shoda

Iijima

et al. 2023

ApJ

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“…It is widely believed that Alfvénic waves, and their associated energy dissipation mechanisms, may contribute to the problems of coronal heating and acceleration of the solar wind (e.g., see the review by Van Doorsselaere et al 2020). Excellent recent reviews on Alfvénic waves in a solar context can be found in Banerjee et al (2021) and Morton et al (2023).…”

Section: Introductionmentioning

confidence: 99%

Alfvénic Motions Arising from Asymmetric Acoustic Wave Drivers in Solar Magnetic Structures

Skirvin¹,

Gao

Doorsselaere³

2023

ApJ

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Alfvénic motions are ubiquitous in the solar atmosphere and their observed properties are closely linked to those of photospheric p-modes. However, it is still unclear how a predominantly acoustic wave driver can produce these transverse oscillations in the magnetically dominated solar corona. In this study we conduct a 3D magnetohydrodynamic numerical simulation to model a straight, expanding coronal loop in a gravitationally stratified solar atmosphere which includes a transition region and chromosphere. We implement a driver locally at one foot-point corresponding to an acoustic–gravity wave which is inclined by θ = 15° with respect to the vertical axis of the magnetic structure and is equivalent to a vertical driver incident on an inclined loop. We show that transverse motions are produced in the magnetic loop, which displace the axis of the waveguide due to the breaking of azimuthal symmetry, and study the resulting modes in the theoretical framework of a magnetic cylinder model. By conducting an azimuthal Fourier analysis of the perturbed velocity signals, the contribution from different cylindrical modes is obtained. Furthermore, the perturbed vorticity is computed to demonstrate how the transverse motions manifest themselves throughout the whole non-uniform space. Finally we present some physical properties of the Alfvénic perturbations and present transverse motions with velocity amplitudes in the range 0.2–0.75 km s−1 which exhibit two distinct oscillation regimes corresponding to 42 and 364 s, where the latter value is close to the period of the p-mode driver in the simulation.

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“…Torsional Alfvén waves were also detected in the photosphere of a pore based on the optical flow detection of angular rotation (Stangalini et al 2021). Some of the key insights into these transverse waves in the solar chromosphere are found in excellent reviews (e.g., Srivastava et al 2021;Jess et al 2023;Morton et al 2023).…”

Section: Introductionmentioning

confidence: 99%

“…By applying the transmitting boundary condition, we obtain the formula of Alfvén wave transmission through this layer as a function of frequency, which is then used for the estimate of the velocity amplitude at different atmospheric levels. For simplicity, plasma density and magnetic field are assumed to be uniform across the magnetic fields, so processes like mode conversion, phase mixing, and resonance absorption (e.g., Goossens et al 2011;Morton et al 2023) are not taken into account. We also assume that the kink waves behave like shear Alfvén waves in the way of wave transport along the magnetic field lines.…”

Section: Introductionmentioning

confidence: 99%

Alfvén Wave Connection between the Chromosphere and the Corona of the Sun: An Analytical Study

Chae,

Lee

2023

ApJ

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Alfvén waves are closely relevant to the three outstanding problems in the solar corona: coronal heating, solar wind acceleration, and the fractionization of low first ionization potential (FIP) elements. There has been increasing observational evidence for the Alfvén waves, not only in the corona, but also in the chromosphere. Here we investigate the Alfvén wave connection between the chromosphere and the corona based on the analytical solution of Alfvén waves in a layer where Alfvén speed varies along magnetic field lines with a constant gradient. The wave transmission of the layer is determined by two parameters: the Alfvénic cutoff frequency and the dimensionless thickness of the layer. It is shown that the ponderomotive acceleration originating from Alfvén waves is always directed upward in the solar atmosphere with the peak occurring in the chromosphere-corona transition region in association with downward low-frequency waves. We also find that some velocity amplitudes observed in the chromosphere of quiet regions and all the velocity amplitudes observed in active regions fall short of the theoretical estimates obtained with the assumption that the Alfvén waves generated below the chromosphere transport upward the energy required for the corona. We suggest considering the possibility that the Alfvén waves responsible for the coronal heating and the FIP fractionization originate from above the chromosphere.

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Alfvénic waves in the inhomogeneous solar atmosphere

Cited by 20 publications

References 250 publications

Magnetic Tornado Properties: A Substantial Contribution to the Solar Coronal Heating via Efficient Energy Transfer

Magnetic Tornado Properties: A Substantial Contribution to the Solar Coronal Heating via Efficient Energy Transfer

Alfvénic Motions Arising from Asymmetric Acoustic Wave Drivers in Solar Magnetic Structures

Alfvén Wave Connection between the Chromosphere and the Corona of the Sun: An Analytical Study

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