Acoustic Wave Properties in Footpoints of Coronal Loops in 3D MHD Simulations

Riedl, Julia M.; Doorsselaere, Tom Van; Reale, F.; Goossens, Marcel; Petralia, Antonino; Pagano, Paolo

doi:10.3847/1538-4357/ac23c7

Cited by 7 publications

(17 citation statements)

References 83 publications

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“…Following the initial setup for the simulations of Riedl et al (2021), we use the same coronal loop model of Reale et al (2016) featuring a straightened, evacuated loop spanning from photosphere to photosphere in a cylindrical coordinate system. The initial equilibrium is obtained by numerically relaxing a hydrostatic model over time, featuring a photosphere, transition region (TR), and corona, with vertical and straight magnetic field (Guarrasi et al 2014).…”

Section: Modelmentioning

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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Section: Modelmentioning

confidence: 99%

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

Skirvin¹,

Gao

Doorsselaere³

2023

ApJ

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“…It was found that these modes couple efficiently to Alfvén waves through resonant absorption (Hansen & Cally 2009;Cally & Andries 2010;Khomenko & Cally 2012). Currently, investigations into what happens if the cross-field structuring is included in the wave propagation model are ongoing (Cally & Khomenko 2019;Riedl et al 2019Riedl et al , 2021. Another crucial ingredient is the wave's behaviour in strong (i.e., non-Wentzel-Kramers-Brillouin, non-WKB) stratification.…”

Section: Introductionmentioning

confidence: 99%

Cutoff of transverse waves through the solar transition region

Pelouze

Doorsselaere

Karampelas

et al. 2023

A&A

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Context. Transverse oscillations are ubiquitously observed in the solar corona, both in coronal loops and in open magnetic flux tubes. Numerical simulations suggest that their dissipation could heat coronal loops, thus counterbalancing radiative losses. These models rely on a continuous driver at the footpoint of the loops. However, analytical works predict that transverse waves are subject to a cutoff in the transition region. It is thus unclear whether they can reach the corona and indeed heat coronal loops. Aims. Our aims are to determine how the cutoff of kink waves affects their propagation into the corona and to characterize the variation of the cutoff frequency with altitude. Methods. Using 3D magnetohydrodynamic simulations, we modelled the propagation of kink waves in a magnetic flux tube, embedded in a realistic atmosphere with thermal conduction, which starts in the chromosphere and extends into the corona. We drove kink waves at four different frequencies and determined whether they experienced a cutoff. We then calculated the altitude at which the waves were cut off and compared it to the prediction of several analytical models. Results. We show that kink waves indeed experience a cutoff in the transition region, and we identified the analytical model that gives the best predictions. In addition, we show that waves with periods shorter than approximately 500 s can still reach the corona by tunnelling through the transition region with little to no attenuation of their amplitude. This means that such waves can still propagate from the footpoints of loop and result in heating in the corona.

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“…It was found that these modes couple efficiently to Alfvén waves through resonant absorption (Hansen & Cally 2009;Cally & Andries 2010;Khomenko & Cally 2012). Currently, investigations are ongoing to what happens if the cross-field structuring is included into the wave propagation model (Cally & Khomenko 2019;Riedl et al 2019Riedl et al , 2021. Another crucial ingredient is the wave's behaviour in strong (i.e.…”

Section: Introductionmentioning

confidence: 99%

Cut-off of transverse waves through the solar transition region

Pelouze¹,

Doorsselaere²,

Karampelas³

et al. 2023

Preprint

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Context. Transverse oscillations are ubiquitously observed in the solar corona, both in coronal loops and open magnetic flux tubes. Numerical simulations suggest that their dissipation could heat coronal loops, counterbalancing radiative losses. These models rely on a continuous driver at the footpoint of the loops. However, analytical works predict that transverse waves are subject to a cut-off in the transition region. It is thus unclear whether they can reach the corona, and indeed heat coronal loops. Aims. Our aims are to determine how the cut-off of kink waves affects their propagation into the corona, and to characterize the variation of the cut-off frequency with altitude. Methods. Using 3D magnetohydrodynamic simulations, we modelled the propagation of kink waves in a magnetic flux tube, embedded in a realistic atmosphere with thermal conduction, that starts in the chromosphere and extends into the corona. We drove kink waves at four different frequencies, and determined whether they experienced a cut-off. We then calculated the altitude at which the waves were cut-off, and compared it to the prediction of several analytical models. Results. We show that kink waves indeed experience a cut-off in the transition region, and we identified the analytical model that gives the best predictions. In addition, we show that waves with periods shorter than approximately 500 s can still reach the corona by tunnelling through the transition region, with little to no attenuation of their amplitude. This means that such waves can still propagate from the footpoints of loop, and result in heating in the corona.

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Acoustic Wave Properties in Footpoints of Coronal Loops in 3D MHD Simulations

Cited by 7 publications

References 83 publications

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

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

Cutoff of transverse waves through the solar transition region

Cut-off of transverse waves through the solar transition region

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