The fast filament eruption leading to the X-flare on March 29, 2014

Abstract

We investigate the sequence of events leading to the solar X1 flare SOL2014-03-29T17:48. Because of the unprecedented joint observations of an X-flare with the ground-based Dunn Solar Telescope and the spacecraft IRIS, Hinode, RHESSI, STEREO, and SDO, we can sample many solar layers from the photosphere to the corona. A filament eruption was observed above a region of previous flux emergence, which possibly led to a change in magnetic field configuration, causing the X-flare. This was concluded from the timing and location of the hard X-ray emission, which started to increase slightly less than a minute after the filament accelerated. The filament showed Doppler velocities of $\sim$2-5 km s${}^{-1}$ at chromospheric temperatures for at least one hour before the flare occurred, mostly blueshifts, but also redshifts near its footpoints. 15 minutes before the flare, its chromospheric Doppler shifts increased to $\sim$6-10 km s${}^{-1}$ and plasma heating could be observed, before it lifted off with at least 600 km s${}^{-1}$, as seen in IRIS data. Compared to previous studies, this acceleration ($\sim$3-5 km s${}^{-2}$) is very fast, while the velocities are in the common range for coronal mass ejections. An interesting feature was a low-lying twisted second filament near the erupting filament, which did not seem to participate in the eruption. After the flare ribbons started on each of the second filament's sides, it seems to have untangled and vanished during the flare. These observations are some of the highest resolution data of an X-class flare to date and reveal some small-scale features yet to be explained.

Accepted for publication by ApJ

References in corpus (4)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• Observations and modeling of the early acceleration phase of erupting filaments involved in coronal mass ejections
• On the Origin of a Sunquake during the 29 March 2014 X1 Flare
• Hα spectroscopy and multiwavelength imaging of a solar flare caused by filament eruption

Cited by in corpus (14)

• Magnetic Properties of Solar Active Regions that Govern Large Solar Flares and Eruptions
• The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares I: Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29
• Spectral signatures of chromospheric condensation in a major solar flare
• Numerical Simulations of Flare-productive Active Regions: delta-sunspots, Sheared Polarity Inversion Lines, Energy Storage, and Predictions
• First Detection of Chromospheric Magnetic Field Changes During an X1-Flare
• Non-Gaussian Velocity Distributions in Solar Flares from Extreme Ultraviolet Lines: A Possible Diagnostic of Ion Acceleration
• Observations and Modelling of the Pre-Flare Period of the 29 March 2014 X1 Flare
• Determining the dynamics and magnetic fields in He I 10830 Å during a solar filament eruption
• Moreton and EUV Waves Associated with an X1.0 Flare and CME Ejection
• Strong Blue Asymmetry in Hα line as a Preflare Activity
• Electric current evolution at the footpoints of solar eruptions
• High-resolution Observation of Downflows at One End of a Pre-eruption Filament
• Continuum enhancements, line profiles and magnetic field evolution during consecutive flares
• Self-consistent Nonlinear Force-free Field Reconstruction from Weighted Boundary Conditions