Article
Engineering, Aerospace
Eric Priest
Summary: Magnetic reconnection is a fundamental process occurring on the Sun, which changes the magnetic topology and converts magnetic energy into other forms. While the understanding of reconnection in two dimensions is quite developed, the behavior in three dimensions is different and has been extensively studied. Some aspects of solar flares can be explained by 2D reconnection models, but a 3D understanding is needed for other aspects such as the shapes of flare ribbons, particle acceleration, and the creation of twist in erupting flux ropes. Recent observations and realizations have stimulated a paradigm shift in our understanding of coronal heating by reconnection, suggesting its role in nanoflare heating events and possible campfires.
ADVANCES IN SPACE RESEARCH
(2023)
Article
Astronomy & Astrophysics
Rebecca A. Robinson, Guillaume Aulanier, Mats Carlsson
Summary: In this study, it is found that low-altitude twisted magnetic fields can generate nanoflares in the quiet Sun's corona. These twisted fields are formed by the coalescence of multiple current-carrying flux tubes, which are continuously reconnecting due to complex flows. As a result, a well-ordered flux rope is formed and later reconnects with surrounding fields. These findings provide insights into the formation of nanoflares in the quiet Sun.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Rebecca A. Robinson, Mats Carlsson, Guillaume Aulanier
Summary: The study aims to investigate magnetic reconnection in the quiet Sun and explore its contribution to solar atmospheric heating. By comparing a complex stratified model to earlier idealized coronal models, the researchers found good agreement in terms of reconnection drivers and topological conditions. The results suggest that magnetic helicity may be transferred via smaller reconnection events in the quiet Sun, indicating a mechanism for ubiquitous heating events.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Physics, Multidisciplinary
K. Bora, Satyam Agarwal, Sanjay Kumar, R. Bhattacharyya
Summary: In this study, a novel Hall magnetohydrodynamics simulation is used to investigate the formation and evolution of a three-dimensional magnetic flux rope. It is found that the evolution of the flux rope is faster and more complex in the Hall magnetohydrodynamics simulation compared to the traditional magnetohydrodynamics simulation. The magnetic reconnections at null points in three-dimensional space play a significant role in the evolution of the flux rope.
Article
Physics, Fluids & Plasmas
A. Zocco, P. Helander, H. Weitzner
Summary: Investigation of magnetic reconnection in 3D fusion devices using a set of non-linear equations suitable for stellarators, with considerations for magnetic flux unfreezing and electron inertia. Emphasis on the role of magnetic geometry in affecting reconnecting instabilities, and discussion of the impact of 3D coupling on linear reconnection rates and mode structures.
PLASMA PHYSICS AND CONTROLLED FUSION
(2021)
Article
Astronomy & Astrophysics
V. Aslanyan, D. I. Pontin, P. F. Wyper, R. B. Scott, S. K. Antiochos, C. R. DeVore
Summary: This study investigates the impact of interchange reconnection on the plasma and magnetic field structure in the heliosphere. Simulation results show that under specific conditions, interchange reconnection leads to the formation of new flux bundles, extending the magnetic field structure.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
T. Pellegrin-Frachon, S. Masson, E. Pariat, P. F. Wyper, C. R. DeVore
Summary: This study investigates the generation of the slow solar wind through 3D magnetohydrodynamic simulations of a magnetic structure known as a pseudo-streamer. The research reveals the dynamics involved in the injection of coronal plasma into the interplanetary medium by studying the connectivity of magnetic field lines.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Thibaud Richard, Pierre Lesaffre, Edith Falgarone, Andrew Lehmann
Summary: This study systematically investigates the physical nature of intense dissipation regions in decaying isothermal magnetohydrodynamical turbulence. The results reveal that these regions mainly correspond to sheets and can be categorized as fast and slow shocks or Alfven discontinuities. The study also finds that the initial conditions and the magnetic Prandtl number have different impacts on the distributions and heating rates within these structures. Additionally, the study shows a strong correlation between the entrance characteristics of the structures.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Hillier, V. Polito
Summary: Quiescent prominences host a variety of flows, with many being driven by buoyancy leading to velocity shear. These shear flows can bend and stretch the magnetic field, forming current sheets that may result in magnetic reconnection.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Sanjay Kumar, Sushree S. Nayak, Avijeet Prasad, Ramit Bhattacharyya
Summary: The study uses three-dimensional magnetohydrodynamic simulations to explore magnetic reconnections in the presence of 3D magnetic nulls and quasi-separatrix layers (QSLs). Through two simulations under different magnetic field conditions, it is observed that rotational driving leads to stronger QSL reconnection in scenarios with weaker magnetic fields and larger domes.
Article
Astronomy & Astrophysics
E. Pariat, P. F. Wyper, L. Linan
Summary: This study compares the dynamics of magnetic energy and helicity using two 3D magnetohydrodynamics parametric simulations. The results show that systems capable of generating jets have higher values of non-potential energy and helicity. During the jet-generation phase, magnetic energies remain relatively constant while magnetic helicities show noticeable changes. The ratio of non-potential helicity to total relative magnetic helicity reaches its highest value when the jet is generated, highlighting the importance of helicity in the trigger mechanism of solar eruptions.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Antonios Nathanail, Vasilis Mpisketzis, Oliver Porth, Christian M. Fromm, Luciano Rezzolla
Summary: Magnetic reconnection plays a key role in the energy dissipation of plasma near a black hole, producing plasmoids that contribute to gamma-ray, X-ray, and near-infrared flares. Through 3D simulations, we observe the formation of current sheets and plasmoids in accretion flows around black holes. These plasmoids gain energy through reconnection and some can even escape the black hole. We quantify the magnetic dissipation and energy transfer process.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Cristian Vega, Vadim Roytershteyn, Gian Luca Delzanno, Stanislav Boldyrev
Summary: This study investigates three-dimensional kinetic-scale turbulence numerically under strongly magnetized conditions. The simulations show that the turbulent cascade in these regimes can reach scales smaller than the electron inertial scale, leading to the formation of electron-scale current sheets. Statistical analysis reveals that the thickness of these current sheets is on the order of the electron inertial length or below, while their half-length falls between the electron and ion inertial length. The pressure-strain interaction, used as a measure of energy dissipation, exhibits high intermittency, with the majority of the total energy exchange occurring in current structures occupying about 20% of the total volume. Some of the current sheets associated with the largest pressure-strain interaction are found to be connected to Alfvenic electron jets and magnetic configurations typical of reconnection.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Geosciences, Multidisciplinary
Hongtao Huang, Yanting Hu, Yongli Ping, Tongpu Yu
Summary: Through particle-in-cell simulations, scientists have successfully created electron-only magnetic reconnection via laser-plasma interactions. In this process, the reconnection current sheet is primarily carried by electrons, while the ion outflow is negligible. By investigating the energy conversion during the reconnection, researchers found that the reconnection electric field plays a crucial role.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Minna Palmroth, Tuija I. Pulkkinen, Urs Ganse, Yann Pfau-Kempf, Tuomas Koskela, Ivan Zaitsev, Markku Alho, Giulia Cozzani, Lucile Turc, Markus Battarbee, Maxime Dubart, Harriet George, Evgeniy Gordeev, Maxime Grandin, Konstantinos Horaites, Adnane Osmane, Konstantinos Papadakis, Jonas Suni, Vertti Tarvus, Hongyang Zhou, Rumi Nakamura
Summary: Rapid plasma eruptions release tremendous energy within Earth's magnetosphere, at the Sun and other planets. The exact mechanism leading to these eruptions, called plasmoids, has been a long-standing question in space physics. Two competing paradigms, magnetic reconnection and kinetic instabilities, have been proposed to explain the process.
Article
Astronomy & Astrophysics
Gherardo Valori, Pascal Demoulin, Etienne Pariat, Anthony Yeates, Kostas Moraitis, Luis Linan
ASTRONOMY & ASTROPHYSICS
(2020)
Article
Astronomy & Astrophysics
Siegfried Gonzi, M. Weinzierl, F. -X. Bocquet, M. M. Bisi, D. Odstrcil, B. V. Jackson, A. R. Yeates, D. R. Jackson, C. J. Henney, C. Nick Arge
Summary: Predicting the physical parameters of solar wind at Earth is essential for space weather forecasts, with models like WSA and ENLIL commonly used for heliospheric transport. This study compared different boundary conditions and found that models have biases and low correlation coefficients, with IPS-driven simulations showing higher success rates. The choice of coronal magnetic field model significantly influences the results, and forecasts do not degrade over longer forecast times.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2021)
Article
Mechanics
L. Chen, A. R. Yeates, A. J. B. Russell
Summary: This study examines the simplest unstirred pattern that may be reached under incompressible advection given a passive tracer distribution f (x, y). Two approaches are tested, with the magnetic relaxation scheme proving to be more robust and able to maintain the initial topology in complex mixed patterns modelled on field line helicity of 3-D magnetic braids. The velocity field is found to have the same large-scale topology as f, supporting the importance of advection in field line helicity evolution.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Fluids & Plasmas
A. R. Yeates, A. J. B. Russell, G. Hornig
Summary: The research shows that plasma relaxation in the presence of an initially braided magnetic field can lead to self-organization into relaxed states that retain non-trivial magnetic structure. Additionally, it reveals that the evolution of individual field line helicities provides new insights into the relaxation process, and predicts the formation of a relaxed state with two discrete flux tubes.
PHYSICS OF PLASMAS
(2021)
Article
Astronomy & Astrophysics
P. Bhowmik, A. R. Yeates
Summary: This study explores the dynamics of the coronal magnetic field during solar minimum, revealing that despite the low solar activity, the corona is still evolving dynamically and releasing magnetic free energy and helicity, leading to eruptive events. These events can be classified into two types, one caused by eruption of low-lying coronal flux ropes, and the other driven by eruption of overlying sheared arcades, differing significantly in the amount of magnetic flux and helicity released.
Article
Astronomy & Astrophysics
Oliver E. K. Rice, Anthony R. Yeates
Summary: This study introduces an improved magnetic field model for calculating magneto-frictional equilibrium in the solar corona, which shows better fit to observational data and takes similar computation time compared to the potential field model. The model provides a practical alternative for initializing time-evolving simulations and modeling the heliospheric magnetic field.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
A. R. Yeates
Summary: The magneto-frictional method is examined in this study for its accuracy in predicting the relaxed state of the Sun's coronal magnetic field. The results show that magneto-friction is unable to reach the exact relaxed state and leads to breakdown of magnetic flux conservation.
GEOPHYSICAL AND ASTROPHYSICAL FLUID DYNAMICS
(2022)
Article
Physics, Multidisciplinary
Christopher B. Prior, Anthony R. Yeates
Summary: Braided vector fields on cylinder-like spatial subdomains are crucial in various applications, with their topology characterized by a quantity called field line winding. This measure uniquely classifies the topology of braided vector fields based on the entanglement of each field line with others, offering a fundamental perspective on the field line topology without conflating linking information with field strength.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Astronomy & Astrophysics
Duncan H. Mackay, Anthony R. Yeates
Summary: The importance of determining the horizontal electric field in 3D data-driven simulations of solar magnetic fields is highlighted, with a comparison between two different techniques. Results show that the sparse technique introduced by Yeates (2017) presents significant challenges in certain aspects, requiring further investigation and exploration.
Article
Astronomy & Astrophysics
P. Bhowmik, A. R. Yeates, O. E. K. Rice
Summary: Coronal mass ejections (CMEs) are highly energetic events originating from the Sun that can disrupt the magnetic and particulate environment of the heliosphere. This paper explores the possibility of predicting stealth CMEs, which exhibit no detectable signatures, using the magnetofrictional model for the coronal magnetic field. The authors show that this model can reproduce stealth CME events and predict repeated eruptions without clear low-coronal signatures.
Article
Astronomy & Astrophysics
Oliver E. K. Rice, Anthony R. Yeates
Summary: This study applies the magneto-frictional method to investigate the best predictor for the loss of equilibrium of a translationally-invariant magnetic flux rope. Through a parameter study, it is found that major eruptions can be best predicted by thresholds in the ratios of squared rope current to either magnetic energy or relative magnetic helicity, rather than individual quantities. Furthermore, the study reveals that the eruptivity index has weak predictive skill and is lower prior to eruption.
FRONTIERS IN ASTRONOMY AND SPACE SCIENCES
(2022)
Article
Astronomy & Astrophysics
Anthony R. Yeates, Prantika Bhowmik
Summary: We present a new automated technique for active region emergence in coronal magnetic field models. This technique allows for the preservation of arbitrary shapes of magnetic field distribution associated with individual active regions and incorporates emerging magnetic helicity in a parametrized manner. The results show that changing the sign and amplitude of the twist parameters profoundly influences the amount of nonpotentiality generated in the global coronal magnetic field.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Kalpa Henadhira Arachchige, Ofer Cohen, Andres Munoz-Jaramillo, Anthony R. Yeates
Summary: This study introduces a synthetic magnetogram as an input for solar wind models and compares the results with observed magnetograms using a space weather modeling framework. By comparing extreme ultraviolet images and simulation data with in situ observations, the ability of dynamo models to be used as input for solar wind models can be quantified.
ASTROPHYSICAL JOURNAL
(2022)
Review
Astronomy & Astrophysics
Mike Lockwood, Mathew J. Owens, Stephanie L. Yardley, Iiro O. I. Virtanen, Anthony R. Yeates, Andres Munoz-Jaramillo
Summary: This study compares historic solar activity observations during the rise and peak of the Modern Grand Solar Maximum (MGSM) with observations of the decline that has followed. The research focuses on the use of accurate magnetograms and Polar Crown Filaments to interpret the rise, as well as analyzing eclipse images and polar coronal hole fluxes for long-term variability and flux transfer dynamics. The findings suggest a potential solution to the open flux problem lies within the streamer belt, emphasizing the importance of understanding asymmetries in flux emergence and potential-based coronal field modeling.
FRONTIERS IN ASTRONOMY AND SPACE SCIENCES
(2022)
Review
Astronomy & Astrophysics
Anthony R. Yeates, Mark C. M. Cheung, Jie Jiang, Kristof Petrovay, Yi-Ming Wang
Summary: This paper reviews the surface flux transport model for the evolution of magnetic flux patterns on the Sun's surface. The focus is on the classical model, with recent advances in understanding transport parameters and the source term. The paper also discusses the physical justification for the model and efforts to incorporate radial diffusion, and summarizes the main directions where researchers have moved beyond the classical model.
SPACE SCIENCE REVIEWS
(2023)