Observations of a white-light flare associated with a filament eruption

TL;DR

This study documents a white-light flare linked to a filament eruption, revealing detailed multi-wavelength observations and magnetic field analysis that support the back-warming mechanism and magnetic reconnection as key processes.

Contribution

It provides new insights into the magnetic topology and temporal evolution of a white-light flare associated with filament eruption, using multi-wavelength data and magnetic field extrapolations.

Findings

White-light emission lagged HXR and microwave emissions by 1-2 minutes.

Magnetic field analysis shows a fan-spine structure with a flux rope underneath.

Reconnection processes likely cause the observed white-light enhancement.

Abstract

We present observations of an M5.7 white-light flare (WLF) associated with a small filament eruption in NOAA active region 11476 on 2012 May 10. During this flare, a circular flare ribbon appeared in the east and a remote brightening occurred in the northwest of the active region. Multi-wavelength data are employed to analyze the WLF, including white light (WL), ultraviolet, extreme ultraviolet, hard X-ray (HXR) and microwave. A close spatial and temporal relationship between the WL, HXR and microwave emissions is found in this WLF. However, the peak time of the WL emission lagged that of the HXR and microwave emissions by about 1-2 minutes. Such a result tends to support the back-warming mechanism for the WL emission. Interestingly, the enhanced WL emission occurred at the two footpoints of the filament. Through forced and potential field extrapolations, we find that the three-dimensional magnetic field in the flare region has a fan-spine feature and that a flux rope lies under the dome-like field structure. We describe the entire process of flare evolution into several steps, each producing the sequent brightening below the filament, the circular flare ribbons and the WL enhancement respectively. We suggest that reconnection between the magnetic field of the filament and the overlying magnetic field or reconnection within the flux rope leads to the WL enhancement.