Spectral observations and modeling of a solar white-light flare observed by CHASE

Song, D.-C. et al. (2023) Spectral observations and modeling of a solar white-light flare observed by CHASE. Astrophysical Journal Letters, 952(1), L6. (doi: 10.3847/2041-8213/ace18c)

Abstract

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.

• Item Type: Articles
• Keywords: Solar activity, solar flare spectra, solar flares, solar x-ray emission, solar chromosphere, solar photosphere.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Chen, Dr Xingyao
• Authors: Song, D.-C., Tian, J., Li, Y., Ding, M. D., Su, Y., Yu, S., Hong, J., Qiu, Y., Rao, S., Liu, X., Li, Q., Chen, X., Li, C., and Fang, C.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Astrophysical Journal Letters
• Publisher: IOP Publishing
• ISSN: 2041-8205
• ISSN (Online): 2041-8213
• Copyright Holders: Copyright © 2023 The Authors
• First Published: First published in Astrophysical Journal Letters 952(1):L6
• Publisher Policy: Reproduced under a Creative Commons licence