2016/06/01 by Shinsuke Takasao, Kazunari Shibata · 3 citations
Earth and Planetary Sciences · Physics and Astronomy · #Coronal loop #Coronal mass ejection #Earthquake Detection and Analysis #Flare #Ionosphere and magnetosphere dynamics #Magnetohydrodynamic drive #Magnetohydrodynamics #Oscillation (cell signaling) #Plasma #Solar and Space Plasma Dynamics #Solar flare #Solar physics #astro-ph.SR
paper · pdf · doi:10.3847/0004-637x/823/2/150
30 pages, 9 figures, published in ApJ
openalex publication_date 2016/06/01 · arxiv created 2016/06/30 · arxiv updated 2016/07/01 · openalex created_date 2016/07/22 · openalex updated_date 2026/08/05
ABSTRACT Observations revealed that various kinds of oscillations are excited in solar flare regions. Quasi-periodic pulsations (QPPs) in flare emissions are commonly observed in a wide range of wavelengths. Recent observations have found that fast-mode magnetohydrodynamic (MHD) waves are quasi-periodically emitted from some flaring sites (quasi-periodic propagating fast-mode magnetoacoustic waves; QPFs). Both QPPs and QPFs imply a cyclic disturbance originating from the flaring sites. However, the physical mechanisms remain puzzling. By performing a set of two-dimensional MHD simulations of a solar flare, we discovered the local oscillation above the loops filled with evaporated plasma (above-the-loop-top region) and the generation of QPFs from such oscillating regions. Unlike all previous models for QPFs, our model includes essential physics for solar flares such as magnetic reconnection, heat conduction, and chromospheric evaporation. We revealed that QPFs can be spontaneously excited by the above-the-loop-top oscillation. We found that this oscillation is controlled by the backflow of the reconnection outflow. The new model revealed that flare loops and the above-the-loop-top region are full of shocks and waves, which is different from the previous expectations based on a standard flare model and previous simulations. In this paper, we show the QPF generation process based on our new picture of flare loops and will briefly discuss a possible relationship between QPFs and QPPs. Our findings will change the current view of solar flares to a new view in which they are a very dynamic phenomenon full of shocks and waves.