Spectral Observations and Modeling of a Solar White-light Flare Observed by CHASE |
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Ying Li Submitted: 2023-07-27 08:17
The heating mechanisms of solar white-light flares remain unclear. We present an X1.0 white-light flare on 2022 October 2 (SOL2022-10-02T20:25) observed by the Chinese Hα Solar Explorer that provides two-dimensional spectra in the visible light for the full solar disk with a seeing-free condition. The flare shows a prominent enhancement of ~40% in the photospheric Fe I line at 6569.2 Å, and the nearby continuum also exhibits a maximum enhancement of ~40%. For the continuum near the Fe I line at 6173 Å from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, it is enhanced up to ~20%. At the white-light kernels, the Fe I line at 6569.2 Å has a symmetric Gaussian profile that is still in absorption and the Hα line at 6562.8 Å displays a very broad emission profile with a central reversal plus a red or blue asymmetry. The white-light kernels are cospatial with the microwave footpoint sources observed by the Expanded Owens Valley Solar Array and the time profile of the white-light emission matches that of the hard X-ray emission above 30 keV from the Gamma-ray Burst Monitor (GBM) on Fermi. These facts indicate that the white-light emission is qualitatively related to a nonthermal electron beam. We also perform a radiative hydrodynamic simulation with the electron-beam parameters constrained by the hard X-ray observations from Fermi/GBM. The result reveals that the white-light enhancement cannot be well explained by a pure electron-beam heating together with its induced radiative backwarming but may need additional heating sources such as Alfvén waves.
Authors: De-Chao Song, Jun Tian, Y. Li, M. D. Ding, Yang Su, Sijie Yu, Jie Hong, Ye Qiu, Shihao Rao, Xiaofeng Liu, Qiao Li, Xingyao Chen, Chuan Li, Cheng Fang
Projects: Other
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Publication Status: ApJL published
Last Modified: 2023-08-02 14:34
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