How flux feeding causes eruptions of solar magnetic flux ropes with the hyperbolic flux tube configuration

¹ CAS Key Laboratory of Geospace Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, PR China
e-mail: zhangqh@ustc.edu.cn
² CAS Center for Excellence in Comparative Planetology, University of Science and Technology of China, Hefei 230026, PR China
³ Mengcheng National Geophysical Observatory, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, PR China
⁴ Collaborative Innovation Center of Astronautical Science and Technology, Hefei, Anhui 230026, PR China
⁵ School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, Guangdong 519000, PR China
⁶ Institute for the Study of Earth, Ocean, and Space, University of New Hampshire, Durham, NH 03824, USA

Received: 20 November 2020
Accepted: 26 January 2021

Abstract

Coronal magnetic flux ropes are generally considered to be the core structure of large-scale solar eruptions. Recent observations found that solar eruptions could be initiated by a sequence of flux feeding, during which chromospheric fibrils rise upward from below, and merge with a pre-existing prominence. Further theoretical study has confirmed that the flux feeding mechanism is efficient in causing the eruption of flux ropes that are wrapped by bald patch separatrix surfaces. But it is unclear how flux feeding influences coronal flux ropes that are wrapped by hyperbolic flux tubes (HFTs), and whether it is able to cause the flux-rope eruption. In this paper, we use a 2.5-dimensional magnetohydrodynamic model to simulate the flux feeding processes in HFT configurations. It is found that flux feeding injects axial magnetic flux into the flux rope, whereas the poloidal flux of the rope is reduced after flux feeding. Flux feeding is able to cause the flux rope to erupt, provided that the injected axial flux is large enough so that the critical axial flux of the rope is reached. Otherwise, the flux-rope system evolves to a stable equilibrium state after flux feeding, which might be even farther away from the onset of the eruption, indicating that flux feeding could stabilize the rope system with the HFT configuration in this circumstance.