Solar Prominence Bubble and Plumes Caused By an Eruptive Magnetic Flux Rope

Prominence bubbles and plumes often form near the lower prominence–corona boundary. They are believed to play an important role in mass supply and evolution of solar prominences. However, how they form is still an open question. In this Letter we present a unique high-resolution Hα observation of a quiescent prominence by the New Vacuum Solar Telescope. Two noteworthy bubble–plume events are studied in detail. The two events are almost identical, except that an erupting mini filament appeared below the prominence–bubble interface in the second event, unlike the first one or any of the reported bubble observations. Analysis of the Hα and extreme-ultraviolet data indicates that the rising magnetic flux rope (MFR) in the mini filament is the cause of bubble expansion and that the interaction between the prominence and MFR results in plume formation. These observations provided clear evidence that emerging MFR may be a common trigger of bubbles and suggested a new mechanism of plumes in addition to Rayleigh–Taylor instability and reconnection.

Turbulence characteristics of Solar Prominences due to Rayleigh Taylor Instabilities

<p>The purpose of our study is to deepen our understanding on the turbulence that arises from Rayleigh Taylor Instabilities in quiescent solar prominences. Quiescent prominences in the solar corona are cool and dense condensates that show internal dynamics over a wide range of spatial and temporal scales. These dynamics are dominated by vertical flows in the prominence body where the mean magnetic field is predominantly in the horizontal direction and the magnetic pressure suspends the dense prominence material. We perform numerical simulations using  MPI-AMRVAC (http://amrvac.org) to study the Rayleigh Taylor Instabilitiy at the prominence-corona transition region using the Ideal-magentohydrodyamics approach. High resolution simulations achieve a resolution of ∼23 km for ∼21 min transitioning from a multi-mode perturbation instability to the non-linear regime and finally a fully turbulent prominence. We use statistical methods to quantify the rich dynamics in quiescent prominence as being indicative of turbulence.</p>

Statistical analysis of UV spectra of a quiescent prominence observed by IRIS

Context. The paper analyzes the structure and dynamics of a quiescent prominence that occurred on October 22, 2013 and was observed by several instruments including the Interface Region Imaging Spectrograph (IRIS). Aims. We aim to determine the physical characteristics of the observed prominence using Mg II k and h (2796 and 2803 Å), C II (1334 and 1336 Å), and Si IV (1394 Å) lines observed by IRIS. In addition we study the dynamical behavior of the prominence. Methods. We employed the one-dimensional non-LTE (departures from the local thermodynamic equilibrium – LTE) modeling of Mg II lines assuming static isothermal-isobaric slabs. We selected a large grid of models with realistic input parameters expected for quiescent prominences (temperature, gas pressure, effective thickness, microturbulent velocity, height above the solar surface) and computed synthetic Mg II lines. The method of Scargle periodograms was used to detect possible prominence oscillations. Results. We analyzed 2160 points of the observed prominence in five different sections along the slit averaged over ten pixels due to low signal to noise ratio in the C II and Si IV lines. We computed the integrated intensity for all studied lines, while the central intensity and reversal ratio was determined only for both Mg II and C II 1334 lines. We plotted several correlations: time evolution of the integrated intensities and central intensities, scatter plots between all combinations of line integrated intensities, and reversal ratio as a function of integrated intensity. We also compared Mg II observations with the models. Results show that more than two-thirds of Mg II profiles and about one-half of C II 1334 profiles are reversed. Profiles of Si IV are generally unreversed. The Mg II and C II lines are optically thick, while the Si IV line is optically thin. Conclusions. The studied prominence shows no global oscillations in the Mg II and C II lines. Therefore, the observed time variations are caused by random motions of fine structures with velocities up to 10 km s−1. The observed average ratio of Mg II k to Mg II h line intensities can be used to determine the prominence’s characteristic temperature. Certain disagreements between observed and synthetic line intensities of Mg II lines point to the necessity of using more complex two-dimensional multi-thread modeling in the future.