Quiescent Prominence Dynamics Observed with the Hinode Solar Optical Telescope. II. Prominence Bubble Boundary Layer Characteristics and the Onset of a Coupled Kelvin–Helmholtz Rayleigh–Taylor Instability

Berger, Thomas; Hillier, Andrew; Liu, W.

doi:10.3847/1538-4357/aa95b6

Cited by 46 publications

(77 citation statements)

References 66 publications

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“…Since the earliest appearance of the bubble, we find the signatures of rapid rotational motion within the bubble with a speed much faster relative to the intrinsic motions exhibited by the prominence material. These flows are found to be present within the bubble (Figure 2) as well as along its boundary (Figure 4) and can be characterized as shear flows (Berger et al, 2017). During the uprise and expansion phase of the bubble, prominence material gets accumulated on the boundary of the bubble.…”

Section: Discussionmentioning

confidence: 98%

Mass Motion in a Prominence Bubble Revealing a Kinked Flux Rope Configuration

Awasthi¹,

Li²

2019

Front. Phys.

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Prominence bubbles are cavities rising into quiescent prominences from below. The bubble-prominence interface is often the active location for the formation of plumes, which flow turbulently into quiescent prominences. Not only the origin of prominence bubbles is poorly understood, but most of their physical characteristics are still largely unknown. Here, we investigate the dynamical properties of a bubble, which is observed since its early emergence beneath the spine of a quiescent prominence on 20 October 2017 in the Hα line-center and in ±0.4Å line-wing wavelengths by the 1m New Vacuum Solar Telescope. We report the prominence bubble to be exhibiting a disparate morphology in the Hα line-center compared to its line-wings' images, indicating a complex pattern of mass motion along the line-of-sight. Combining Doppler maps with flow maps in the plane of sky derived from a Nonlinear Affine Velocity Estimator, we obtained a comprehensive picture of mass motions revealing a counterclockwise rotation inside the bubble; with blue-shifted material flowing upward and red-shifted material flowing downward. This sequence of mass motions is interpreted to be either outlining a kinked flux rope configuration of the prominence bubble or providing observational evidence of the internal kink instability in the prominence plasma.

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Section: Discussionmentioning

confidence: 98%

Mass Motion in a Prominence Bubble Revealing a Kinked Flux Rope Configuration

Awasthi¹,

Li²

2019

Front. Phys.

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“…Therefore, the most unstable modes become those that vary little along the field. This instability has been found to occur in a number of different situations in the solar atmosphere including in the interaction between prominences and bubbles that form below them (Ryutova et al 2010;Berger et al 2010Berger et al , 2017, or internal prominence motions (Hillier & Polito 2018;Yang et al 2018), and as a result of eruptions in the solar atmosphere (Foullon et al 2011;Ofman & Thompson 2011;Möstl et al 2013). Soler et al (2010) investigated how this instability develops on the surface of a rotating flux tube, a model used because of its geometrical connection to coronal loops, finding that the fundamental physics of the linear instability are not greatly altered by the change in geometry.…”

Section: Introductionmentioning

confidence: 99%

Coronal Cooling as a Result of Mixing by the Nonlinear Kelvin–Helmholtz Instability

Hillier

Arregui

2019

ApJ

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Recent observations show cool, oscillating prominence threads fading when observed in cool spectral lines and appearing in warm spectral lines. A proposed mechanism to explain the observed temperature evolution is that the threads were heated by turbulence driven by the Kelvin-Helmholtz instability that developed as a result of wave-driven shear flows on the surface of the thread. As the Kelvin-Helmholtz instability is an instability that works to mix the two fluids either side of the velocity shear layer, in the solar corona it can be expected to work by mixing the cool prominence material with that of the hot corona to form a warm boundary layer. In this paper we develop a simple phenomenological model of nonlinear Kelvin-Helmholtz mixing, using it to determine the characteristic density and temperature of the mixing layer, which for the case under study with constant pressure across the two fluids are ρ mixed = √ ρ 1 ρ 2 and T mixed = √ T 1 T 2 . One result from the model is that it provides an accurate, as determined by comparison with simulation results, determination of the kinetic energy in the mean velocity field. A consequence of this is that the magnitude of turbulence, and with it the energy that can be dissipated on fast time-scales, as driven by this instability can be determined. For the prominence-corona system, the mean temperature rise possible from turbulent heating is estimated to be less than 1% of the characteristic temperature (which is found to be T mixed = 10 5 K). These results highlight that mixing, and not heating, are likely to be the cause of the observed transition between cool to warm material in Okamoto et al. (2015). One consequence of this result is that the mixing creates a region with higher radiative loss rates on average than either of the original fluids, meaning that this instability could contribute a net loss of thermal energy from the corona, i.e. coronal cooling.

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“…In the solar atmosphere, KH instability is observed at a variety of scales, e.g., as growing ripples at the interface between a prominence and the corona (Ryutova et al 2010;Berger et al 2017;Yang et al 2018;Hillier & Polito 2018). KH and other plasma instabilities are believed to be the key processes in dispersing and evaporating cool prominence material into the hot corona (Berger et al 2017;Hillier & Polito 2018;Li et al 2018a). Ofman & Thompson (2011) reported the growth and saturation of KH vortices at the interface between erupting and non-erupting plasmas during a coronal material ejection (CME) event.…”

Section: Introductionmentioning

confidence: 99%

Multilayered Kelvin–Helmholtz Instability in the Solar Corona

Yuan

Shen

Liu

et al. 2019

ApJL

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The Kelvin-Helmholtz (KH) instability is commonly found in many astrophysical, laboratory, and space plasmas. It could mix plasma components of different properties and convert dynamic fluid energy from large scale structure to smaller ones. In this study, we combined the ground-based New Vacuum Solar Telescope (NVST) and the Solar Dynamic Observatories (SDO) / Atmospheric Imaging Assembly (AIA) to observe the plasma dynamics associated with active region 12673 on 09 September 2017. In this multi-temperature view, we identified three adjacent layers of plasma flowing at different speeds, and detected KH instabilities at their interfaces. We could unambiguously track a typical KH vortex and measure its motion. We found that the speed of this vortex suddenly tripled at a certain stage. This acceleration was synchronized with the enhancements in emission measure and average intensity of the 193Å data. We interpret this as evidence that KH instability triggers plasma heating. The intriguing feature in this event is that the KH instability observed in the NVST channel was nearly complementary to that in the AIA 193Å. Such a multi-thermal energy exchange process is easily overlooked in previous studies, as the cold plasma component is usually not visible in the extreme ultraviolet channels that are only sensitive to high temperature plasma emissions. Our finding indicates that embedded cold layers could interact with hot plasma as invisible matters. We speculate that this process could occur at a variety of length scales and could contribute to plasma heating.

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Quiescent Prominence Dynamics Observed with the Hinode Solar Optical Telescope. II. Prominence Bubble Boundary Layer Characteristics and the Onset of a Coupled Kelvin–Helmholtz Rayleigh–Taylor Instability

Cited by 46 publications

References 66 publications

Mass Motion in a Prominence Bubble Revealing a Kinked Flux Rope Configuration

Mass Motion in a Prominence Bubble Revealing a Kinked Flux Rope Configuration

Coronal Cooling as a Result of Mixing by the Nonlinear Kelvin–Helmholtz Instability

Multilayered Kelvin–Helmholtz Instability in the Solar Corona

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