Abstract
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 H$\alpha$ line-center and in $\pm$0.4 angstrom line-wing wavelengths by the 1-m New Vacuum Solar Telescope. We report the prominence bubble to be exhibiting a disparate morphology in the H$\alpha$ 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 counter-clockwise 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.
Highlights
It is crucial to understand the dynamical characteristics and magnetic field configuration of the solar prominences primarily due to their association with the solar eruptions
We investigate the mass motion in a quiescent prominence of October 20, 2017, located at the north-east limb of the solar disk (N24E87)
The bubble is seen in the form of a dark cavity in the Hα line center whereas the same appears bright surrounded by dark threads in the extreme ultra-violet (EUV) observations
Summary
It is crucial to understand the dynamical characteristics and magnetic field configuration of the solar prominences primarily due to their association with the solar eruptions. It is crucial to determine the physical mechanisms responsible for the formation, uprise, and expansion of the bubbles It is unclear what is inside the prominence bubble. Of particular interest was the observation of a hot rising structure (logT≈6.0) within a prominence bubble investigated in Berger et al [8], which was argued to play a crucial role in the formation and expansion of the bubble through pushing the cooler prominence material upwards. They further inferred “magneto-thermal convection” process to be responsible for the expansion of the prominence bubble.
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