Abstract
Magnetohydrodynamic (MHD) instabilities allow energy to be released from stressed magnetic fields, commonly modelled in cylindrical flux tubes linking parallel planes, but, more recently, also in curved arcades containing flux tubes with both footpoints in the same photospheric plane. Uncurved cylindrical flux tubes containing multiple individual threads have been shown to be capable of sustaining an MHD avalanche, whereby a single unstable thread can destabilise many. We examine the properties of multi-threaded coronal loops, wherein each thread is created by photospheric driving in a realistic, curved coronal arcade structure (with both footpoints of each thread in the same plane). We use three-dimensional MHD simulations to study the evolution of single- and multi-threaded coronal loops, which become unstable and reconnect, while varying the driving velocity of individual threads. Experiments containing a single thread destabilise in a manner indicative of an ideal MHD instability and consistent with previous examples in the literature. The introduction of additional threads modifies this picture, with aspects of the model geometry and relative driving speeds of individual threads affecting the ability of any thread to destabilise others. In both single- and multi-threaded cases, continuous driving of the remnants of disrupted threads produces secondary, aperiodic bursts of energetic release.
Highlights
Despite incredible advances, in both observations and modelling, our understanding of the exact means through which magnetic energy is released in the solar corona remains limited. 120 Page 2 of 20Solutions to the coronal heating problem likely rely upon a combination of processes (Parnell and De Moortel, 2012)
Twisted flux tubes are commonly associated with bursts of energy released during flares, which attest to their destabilisation and to energy transfer to local heating, waves, and particle acceleration
Our investigation means that we are able to answer the question posed in the title of this work: multi-threaded curved flux tubes are capable of supporting a magnetohydrodynamic avalanche
Summary
In both observations and modelling, our understanding of the exact means through which magnetic energy is released in the solar corona remains limited. Twisted flux tubes are commonly associated with bursts of energy released during flares, which attest to their destabilisation and to energy transfer to local heating, waves, and particle acceleration. Such effects produce distinct, observable signatures across the electromagnetic spectrum. Advances in understanding coronal heating using this hypothesis include those of Browning and Van der Linden (2003), Browning et al (2008), Hood, Browning, and van der Linden (2009), Bareford, Browning, and van der Linden (2010), Bareford, Hood, and Browning (2013) Such models have enabled forward modelling and comparison with observation (Haynes and Arber, 2007; Botha, Arber, and Srivastava, 2012; Pinto, Vilmer, and Brun, 2015; Snow et al, 2017), as well as assessing the role played by certain physical effects, or combinations thereof, known to be present in the solar corona (such as by Botha, Arber, and Hood, 2011; Reale et al, 2016). Our results and conclusions do not depend on the actual choice of boundary conditions (other than the form of the driver)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
