Possible Signature of Sausage Waves in Photospheric Bright Points

Gao, Yuhang; Li, Fuyu; Li, Bo; Cao, Wenda; Song, Yongliang; Guo, Mingzhe

doi:10.1007/s11207-021-01928-9

Cited by 10 publications

(6 citation statements)

References 55 publications

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“…Riedl et al (2021) have shown that a purely vertical driver excites tube waves which are axisymmetric, when the background is also axisymmetric, corresponding to the m = 0 sausage mode of a magnetic cylinder. This result is not entirely unexpected and may explain the axisymmetric perturbations of structures observed in the lower solar atmosphere (Morton et al 2012;Moreels et al 2015;Gao et al 2021;Grant et al 2022). However, with an inclined driver, we expect that tube waves which are non-axisymmetric in nature, i.e., kink waves, should also be excited within the magnetic structure.…”

Section: Wave Modes Excitedmentioning

confidence: 59%

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: Wave Modes Excitedmentioning

confidence: 59%

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

Skirvin¹,

Gao

Doorsselaere³

2023

ApJ

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“…Therefore, while kink-mode waves, associated with the overall centroid motion of the bright point, have been studied extensively, other wave modes associated with the shape of the flux tube cross section are yet underexplored. While efforts have been made to probe wave modes associated with bright point area changes (e.g., Gao et al 2021), observations have been very limited in the wave modes that can be studied.…”

Section: Introductionmentioning

confidence: 99%

Using Bright Point Shapes to Constrain Wave Heating of the Solar Corona: Predictions for DKIST

Van Kooten,

Cranmer

2024

ApJ

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Magnetic bright points on the solar photosphere mark the footpoints of kilogauss magnetic flux tubes extending toward the corona. Convective buffeting of these tubes is believed to excite magnetohydrodynamic waves, which can propagate to the corona and deposit heat there. Measuring wave excitation via bright point motion can thus constrain coronal and heliospheric models, and this has been done extensively with centroid tracking, which can estimate kink-mode wave excitation. DKIST is the first telescope to provide well-resolved observations of bright points, allowing shape and size measurements to probe the excitation of other wave modes that have been difficult, if not impossible, to study to date. In this work, we demonstrate a method of automatic bright point tracking that robustly identifies the shapes of bright points, and we develop a technique for interpreting measured bright point shape changes as the driving of a range of thin-tube wave modes. We demonstrate these techniques on a MURaM simulation of DKIST-like resolution. These initial results suggest that modes other than the long-studied kink mode could increase the total available energy budget for wave heating by 50%. Pending observational verification as well as modeling of the propagation and dissipation of these additional wave modes, this could represent a significant increase in the potency of wave-turbulence heating models.

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“…BPs are considered as tracers of the footpoints of magnetic flux tubes on the photosphere (Berger et al 1998;De Pontieu 2002;Schüssler et al 2003;Yang et al 2016). In addition, BPs are pushed into intergranular lanes, which continuously oscillate under the buffeting of granules, and excited magnetohydrodynamic waves propagate upward through the flux tube and transfer energy into the chromosphere and lower corona to heat these regions of the solar atmosphere (Jess et al 2009;Fedun et al 2010;van Ballegooijen et al 2011;Vigeesh et al 2012;Gao et al 2021;Magyar et al 2021). Thus, BPs play a key role in the various behaviors of magnetic elements in photospheres and in coronal heating .…”

Section: Introductionmentioning

confidence: 99%

Hybrid Detection Algorithm and Study on the Quantity and Brightness Evolution Characteristics of Photospheric Bright Point Groups

Bai,

Yang,

Zhao

et al. 2023

ApJ

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Photospheric bright points (BPs), the smallest magnetic elements in the photosphere, are constantly moving and changing. Studying the characteristics of these small-scale strong magnetic fields with kilogauss magnitudes could be of significant importance for investigating the coronal heating problem. Compared to the study of a few specific BPs, investigating the collective features of BP groups can provide us with a better understanding of the overall characteristics of BPs. However, there is still a lack of research on the evolution of BP groups, and the detection algorithm of BPs still has a lot of space for improvement. We propose a hybrid BP detection model (HBD-Model) that combines traditional algorithms and deep learning to improve detection accuracy. Using the HBD-Model, we focus on studying the evolution characteristics of the quantity and brightness of BP groups at different brightness levels and how these characteristics differ between quiet and active regions. Results show that the activity of BP groups is not random or disorderly. In different brightness levels and regions, their quantity and brightness evolution exhibit periodic or complex changes.

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Possible Signature of Sausage Waves in Photospheric Bright Points

Cited by 10 publications

References 55 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

Using Bright Point Shapes to Constrain Wave Heating of the Solar Corona: Predictions for DKIST

Hybrid Detection Algorithm and Study on the Quantity and Brightness Evolution Characteristics of Photospheric Bright Point Groups

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