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arXiv · 2412.19984

The magnetic origin of the mystery of rare H$\alpha$ Moreton waves

Ze Zhong·Yao Chen·Y. W. Ni·P. F. Chen·Ruisheng Zheng·Xiangliang Kong·Chuan Li
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Abstract

Over the past three decades, a lot of coronal fast-mode waves were detected by space missions, but their counterparts in the chromosphere, called the Moreton waves, were rarely captured. How this happens remains a mystery. Here, to shed light on this problem, we investigate the photospheric vector magnetograms of the Moreton wave events associated with M- and X-class solar flares in 2010--2023. The H$\alpha$ data are taken with the Global Oscillation Network Group (GONG) and the Chinese H$\alpha$ Solar Explorer (CHASE). Our statistical results show that more than 80\% of the events occur at the edge of active regions and propagate non-radially due to asymmetric magnetic fields above the flares. According to the reconstructed magnetic field and atmospheric model, Moreton waves propagate in the direction along which the horizontal fast-mode wave speed drops the fastest. The result supports that the inclined magnetic configuration of the eruption is crucial to generate Moreton waves, even for X-class flares. It may explain the low occurrence rate of Moreton waves and why some X-class flares accompanied with coronal mass ejections (CMEs) do not generate Moreton waves.

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Ze Zhong, Yao Chen, Y. W. Ni, P. F. Chen, Ruisheng Zheng, Xiangliang Kong, Chuan Li. 2024-12-28. The magnetic origin of the mystery of rare H$\alpha$ Moreton waves. https://arxiv.org/abs/2412.19984

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