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

Abstract

We analyze solar quiescent prominence bubble characteristics and instability dynamics using Hinode/Solar Optical Telescope (SOT) data. We measure bubble expansion rate, prominence downflows, and the profile of the boundary layer brightness and thickness as a function of time. The largest bubble analyzed rises into the prominence with a speed of about 1.3 km/s until it is destabilized by a localized shear flow on the boundary. Boundary layer thickness grows gradually as prominence downflows deposit plasma onto the bubble with characteristic speeds of 20 - 35 km/s. Lateral downflows initiate from the thickened boundary layer with characteristic speeds of 25 - 50 km/s, "draining" the layer of plasma. Strong shear flow across one bubble boundary leads to an apparent coupled Kelvin-Helmholtz Rayleigh-Taylor (KH-RT) instability. We measure shear flow speeds above the bubble of 10 km/s and infer interior bubble flow speeds on the order of 100 km/s. Comparing the measured growth rate of the instability to analytic expressions, we infer a magnetic flux density across the bubble boundary of ~10^{-3} T (10 gauss) at an angle of ~70 degrees to the prominence plane. The results are consistent with the hypothesis that prominence bubbles are caused by magnetic flux that emerges below a prominence, setting up the conditions for RT, or combined KH-RT, instability flows that transport flux, helicity, and hot plasma upward into the overlying coronal magnetic flux rope.

17 pages, 7 figures

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Cited by in corpus (13)

• Multi-layered Kelvin-Helmholtz Instability in the Solar Corona
• Coronal cooling as a result of mixing by the nonlinear Kelvin--Helmholtz instability
• The Evolution of Magnetic Rayleigh-Taylor Unstable Plumes and Hybrid KH-RT Instability into A Loop-like Eruptive Prominence
• Large ion-neutral drift velocities and plasma heating in partially ionized coronal rain blobs
• Flow instabilities in solar jets in their upstream and downstream regimes
• Reconstructing 3D Magnetic Topology of On-disk Prominence Bubbles from Stereoscopic Observations
• Mass motion in a prominence bubble revealing a kinked flux rope configuration
• A formation mechanism for the large plumes in the prominence
• Magnetic Rayleigh-Taylor Instability at a Contact Discontinuity With Oblique Magnetic Field
• Shocks and instabilities in the partially ionised solar atmosphere
• Response of the solar atmosphere to flux emergence: With emergence-driven prominence formation
• Nonlinear Fast Magnetosonic Waves in Solar Prominence Pillars
• Observation of Large-Scale Kelvin-Helmholtz Instability Wave Driven by a Coronal Mass Ejection