Magnetic Tornado Properties: A Substantial Contribution to the Solar Coronal Heating via Efficient Energy Transfer

Abstract

In solving the solar coronal heating problem, it is crucial to comprehend the mechanisms by which energy is conveyed from the photosphere to the corona. Recently, magnetic tornadoes, characterized as coherent, rotating magnetic-field structures extending from the photosphere to the corona, have drawn growing interest as a possible means of efficient energy transfer. Despite its acknowledged importance, the underlying physics of magnetic tornadoes remains elusive. In this study, we conduct a three-dimensional radiative magnetohydrodynamic simulation that encompasses the upper convective layer and extends into the corona, with a view to investigating how magnetic tornadoes are generated and efficiently transfer energy into the corona. We find that a single event of magnetic flux concentration merger on the photosphere gives rise to the formation of a single magnetic tornado. The Poynting flux transferred into the corona is found to be four times greater in the presence of the magnetic tornado, as compared to its absence. This increase is attributed to a reduction in energy loss in the chromosphere, resulting from the weakened magnetic-energy cascade. Based on an evaluation of the fraction of the merging events, our results suggest that magnetic tornadoes contribute approximately 50% of the Poynting flux into the corona in regions where the coronal magnetic-field strength is 10 G. Potentially, the contribution could be even greater in areas with a stronger coronal magnetic field.

Magnetohydrodynamic Poynting Flux Vortices in the Solar Atmosphere and Their Role in Concentrating Energy

“…This indicates that observational estimates on the upflow of magnetic energy generated by photospheric motion might overestimate the energy that reaches the upper atmosphere. Our findings also reinforce the role of vortices as energy channels, as they breach these energy transport barriers, resulting in a significant augmentation of the magnetic energy availability in the presence of the vortices, around a three times higher Poynting flux than before, as quantified by Figures 9 and 10 and similarly obtained by Kuniyoshi et al (2023) for a magnetic tornado. After the vortices were established, the input of the magnetic energy into the upper atmosphere by the Poynting flux vortex was around 10 22 erg per second, which is the same amount of energy required by the nanoflare heating scenario (Pontin & Hornig 2020).…”

“…Although previous studies (see, e.g., Wedemeyer-Böhm et al 2012;Yadav et al 2021;Kuniyoshi et al 2023) had already demonstrated the potential role of K-vortices for energy transport, our analysis has shown for the first time how the magnetic energy is flowing in the upper atmosphere and how the presence of vortices shapes the energy distribution. Our results strongly underline the effectiveness of magnetic energy mapping through FTLE in elucidating energy transport characteristics within the solar atmosphere.…”

“…By interacting with magnetic flux tubes, the vortical motions create enough energy to be transported upward and even more effectively produce Poynting flux than other horizontal motions (Yadav et al 2021;Chian et al 2023). Coherently rotating magnetic field structures, the magnetic tornadoes, are found to produce enough Poynting flux to justify chromospheric and coronal temperatures (Wedemeyer-Böhm et al 2012), and their presence leads to an enhancement of the energy flux by four times compared to time intervals in which there are no magnetic tornadoes (Kuniyoshi et al 2023).…”

Can the Solar p-modes Contribute to the High-frequency Transverse Oscillations of Spicules?

“…We perform a two-dimensional numerical simulation that seamlessly covers the upper part of the solar convection zone and the corona. To this end, we use RAMENS 4 code (Iijima & Yokoyama 2015Iijima 2016;Wang et al 2021;Kuniyoshi et al 2023), in which we solve the compressible magnetohydrodynamic equations with gravity, radiation, and thermal conduction. The basic equations are given in the conservation form as follows…”

Formulating Mass-loss Rates for Sun-like Stars: A Hybrid Model Approach

“…Consequently, we adopt λ ⊥,* = 2000 km, slightly exceeding the typical granular scale (1000 km). The legitimacy of this presumption hinges on the wave generation mechanism; if Alfvén waves originate from intergranular-scale vortices (van Ballegooijen et al 2011;Finley et al 2022;Breu et al 2023;Kuniyoshi et al 2023), the scale of the intergranular lane should be designated as λ ⊥,* = 100-200 km (Berger & Title 2001;van Ballegooijen et al 2011). In future studies, the radial profile of λ ⊥ should be more accurately prescribed to align with observations (Abramenko et al 2013;Sharma & Morton 2023).…”