Article
Astronomy & Astrophysics
L. Yu, S. Y. Huang, Z. G. Yuan, K. Jiang, Q. Y. Xiong, S. B. Xu, Y. Y. Wei, J. Zhang, Z. H. Zhang
Summary: A statistical analysis of linear magnetic holes (LMHs) in the solar wind from 0.166 to 0.82 au using Parker Solar Probe observations reveals that LMHs have short durations and depths that slightly increase with heliocentric distance. Around 50% of events show higher plasma temperature and density inside the holes. The occurrence rate of LMHs shows no significant variation with heliocentric distance, with potential locally generated LMHs near 0.525 and 0.775 au. The study also investigates the geometry evolution of LMHs, showing their prolonged shape across and along the magnetic field direction.
ASTROPHYSICAL JOURNAL
(2021)
Article
Physics, Multidisciplinary
Vincenzo Carbone, Fabio Lepreti, Antonio Vecchio, Tommaso Alberti, Federica Chiappetta
Summary: The study of low-frequency fluctuations in the interplanetary medium has revealed universal scaling behavior representing an underlying energy cascade, while the interpretation of high-frequency plasma fluctuations remains a challenge for theoretical modeling. This paper describes high frequency fluctuations in the interplanetary space using a Brownian-like approach and successfully replicates the main features of the observed magnetic fluctuations spectrum. The Fluctuation-Dissipation Relation derived in the model suggests a power law between dissipation rate and temperature, indicating Landau damping as the main mechanism of dissipation in solar wind plasma.
FRONTIERS IN PHYSICS
(2021)
Article
Astronomy & Astrophysics
Ronald M. Caplan, Cooper Downs, Jon A. Linker, Zoran Mikic
Summary: This study investigates the potential field solutions for the global coronal magnetic field on June 13, 2012, and explores how different choices in boundary conditions, resolution, and input maps may influence the solution properties. The results show that coronal morphology and magnetic flux are most strongly influenced by the outer boundary condition, while large-scale morphologies and open magnetic flux are insensitive to model resolution.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Rohit Chhiber, David Ruffolo, William H. Matthaeus, Arcadi Usmanov, Paisan Tooprakai, Piyanate Chuychai, Melvyn L. Goldstein
Summary: The study develops a formalism and uses global magnetohydrodynamic simulations to estimate the diffusive spreading of magnetic field lines originating from different regions of the solar atmosphere. It quantifies angular spreads and source region sizes at 1 au, as well as estimates the filamentation distance up to which field lines can remain trapped in filamentary structures. The role of slab-like fluctuations in the transition to more diffusive transport at greater heliocentric distances is emphasized.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Samuel J. Schonfeld, Carl J. Henney, Shaela Jones, Charles N. Arge
Summary: This study explores the use of observed polar coronal holes to constrain the flux distribution within the polar regions of global solar magnetic field maps. The findings show that modifications to the polar flux can improve predictions for coronal holes and solar wind, and that low-latitude magnetic fields have a significant impact on setting the boundaries of polar coronal holes.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
T. E. Cravens, O. Hamil, A. Renzaglia, S. A. Ledvina, S. K. Howard
Summary: The main sources of the magnetic field in the Martian ionosphere are the solar wind interaction with the planet and remnant crustal magnetization, mainly in the southern hemisphere. This study used Fourier analysis to quantify, interpret, and compare the magnetic fields in the ionosphere and solar wind, suggesting plasma movement from the pile-up region to the ionosphere. The findings also indicate the possible creation of a magnetic structure within the ionosphere itself.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Rohit Chhiber, William H. Matthaeus, Trevor A. Bowen, Stuart D. Bale
Summary: This study used high time-resolution solar wind magnetic field data from the Parker Solar Probe mission to analyze intermittency statistics near the first perihelion. The results revealed multifractal scaling in the inertial range, and monofractal but non-Gaussian scaling in the subproton range, with the transition to monofractality attributed to the presence of scale-invariant current sheets between ion and electron inertial scales. The study also ruled out incoherent kinetic-scale wave activity as a factor in the transition.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
S. Y. Huang, F. Sahraoui, N. Andres, L. Z. Hadid, Z. G. Yuan, J. S. He, J. S. Zhao, S. Galtier, J. Zhang, X. H. Deng, K. Jiang, L. Yu, S. B. Xu, Q. Y. Xiong, Y. Y. Wei, T. Dudok de Wit, S. D. Bale, J. C. Kasper
Summary: The study shows an inverse correlation between power amplitude and spectral steepness at sub-ion scales in solar wind turbulence, as well as a similar trend between steep spectra and increasing normalized cross helicity. It also discusses the ubiquitous nature of the ion transition range in the inner heliosphere.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
I Mann, A. Czechowski
Summary: The FIELDS instrument onboard Parker Solar Probe observes dust impacts on the spacecraft. The derived dust flux rates suggest that the particles originate from the vicinities of the Sun and are ejected by radiation pressure. The study of dust trajectories influenced by gravity, radiation pressure, and the electromagnetic force reveals that fluxes can vary with magnetic field conditions, indicating a time-variable flux of dust smaller than 100 nm entering Earth's atmosphere from the inner Solar System.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
B. R. Ragot
Summary: The dominance of the global over the relative, cross-field transport of magnetic field lines has been confirmed by 23 years of in situ data analysis. The study revealed two new supradiffusive regimes in the dispersal of magnetic field lines, one caused by nonlinear effects and the other due to intermittency in the solar wind. These findings provide further insights into the transport processes of magnetic field lines in the solar wind.
ASTROPHYSICAL JOURNAL
(2023)
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
Piotr Bladek, Romana Ratkiewicz
Summary: This study defines the nose of the heliopause and investigates its variations in location. The displacement of the heliopause nose depends on the direction and intensity of the interstellar magnetic field, while the structure of the heliosphere and the shape of the heliopause depend on the 11-year cycle of solar activity.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Yuri Yermolaev, Irina G. Lodkina, Alexander A. Khokhlachev, Michael Yu Yermolaev, Maria O. Riazantseva, Liudmila S. Rakhmanova, Natalia L. Borodkova, Olga Sapunova, Anastasiia Moskaleva
Summary: This study compares the time profiles of solar wind parameters during high and low solar activity periods and finds that the parameters decrease during low activity periods, but maintain a similar shape to high activity periods, albeit with lower values.
Article
Astronomy & Astrophysics
Raffaella D'Amicis, Denise Perrone, Marco Velli, Luca Sorriso-Valvo, Daniele Telloni, Roberto Bruno, Rossana De Marco
Summary: This paper presents a comparative study on the characterization of Alfvenic turbulence in fast and slow solar wind intervals observed at 1 AU. The study reveals that while there are many similarities between the two solar wind regimes, each stream also shows peculiar features. These findings contribute to the understanding of the evolution of Alfvenicity in the inner heliosphere.
Article
Astronomy & Astrophysics
Alexander A. Khokhlachev, Yuri Yermolaev, Irina G. Lodkina, Maria O. Riazantseva, Liudmila S. Rakhmanova
Summary: The study revealed that the decrease in solar activity in solar cycles affected the behavior of relative helium ions abundance inside interplanetary coronal mass ejections. The helium abundance significantly decreased in the low solar activity period, and the dependence on certain parameters became weaker during this period compared to high solar activity periods. Additionally, a dependence on the distance from spacecraft to the ICME axis was observed, with the maximum helium abundance measured at the minimum distance confirming the hypothesis of an helium-enriched electric current inside an ICME.
Article
Astronomy & Astrophysics
Sean P. Blake, Antti Pulkkinen, Peter W. Schuck, Alex Glocer, Gabor Toth
Summary: The study highlights the importance of considering the equatorward extent of the auroral oval when assessing the risk posed by space weather to ground infrastructure. Results show that the auroral oval in the Northern hemisphere moves South with larger storms. Simulation results indicate that for storms with higher Dst values, the estimates of the auroral equatorward boundary are more accurate, while for extreme storms with very low Dst values, there is a considerable scatter in the estimated location.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Camilla D. K. Harris, Xianzhe Jia, James A. Slavin, Gabor Toth, Zhenguang Huang, Martin Rubin
Summary: A multi-fluid magnetohydrodynamic model was developed to characterize the global configuration of the plasma interaction between Europa and its surrounding magnetospheric plasma, and its accuracy was demonstrated through simulations of Galileo flybys. The model revealed the access of Jovian magnetospheric plasma to Europa's surface and how that access is influenced by changing magnetospheric conditions.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Physics, Fluids & Plasmas
M. Xuan, M. Swisdak, J. F. Drake
Summary: The study focuses on the reversibility of energy transfer from the magnetic field to the surrounding plasma during magnetic reconnection. It demonstrates that irreversibility is associated with separatrix crossings and passages through weaker magnetic field regions. The inclusion of a guide field enhances particle magnetization.
PHYSICS OF PLASMAS
(2021)
Article
Astronomy & Astrophysics
A. T. Michael, M. Opher, G. Toth, V Tenishev, D. Borovikov
Summary: This study presents a new numerical code called SHIELD, which is based on a self-consistent, kinetic-MHD model. The code accurately predicts the filtration of neutral hydrogen into the heliosphere and shows improvement compared to other models.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Nishtha Sachdeva, Gabor Toth, Ward B. Manchester, Bart van der Holst, Zhenguang Huang, Igor Sokolov, Lulu Zhao, Qusai Al Shidi, Yuxi Chen, Tamas Gombosi, Carl J. Henney, Diego G. Lloveras, Alberto M. Vasquez
Summary: To accurately predict the arrival time and geomagnetic impact of solar coronal mass ejections (CMEs), it is essential to model the background solar wind conditions in which CMEs propagate. By using the Alfven Wave Solar atmosphere Model (AWSoM) to simulate solar maximum conditions and validating the results, proper initial conditions for launching CMEs can be provided.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
M. Kornbleuth, M. Opher, I Baliukin, M. Gkioulidou, J. D. Richardson, G. P. Zank, A. T. Michael, G. Toth, V Tenishev, V Izmodenov, D. Alexashov, S. Fuselier, J. F. Drake, K. Dialynas
Summary: Global models of the heliosphere are essential for understanding heliospheric observations. The comparison between two MHD models, BU and Moscow, reveals the impact of different numerical treatments and physical assumptions on the heliospheric solution. Differences in plasma solutions between the two models may affect measurements of the heliosphere.
ASTROPHYSICAL JOURNAL
(2021)
Article
Physics, Multidisciplinary
P. S. Pyakurel, M. A. Shay, J. F. Drake, T. D. Phan, P. A. Cassak, J. L. Verniero
Summary: Observations in Earth's turbulent magnetosheath downstream of a quasiparallel bow shock reveal a prevalence of electron-scale current sheets favorable for electron-only reconnection where ions are not coupled to the reconnecting magnetic fields. In small-scale turbulence, magnetic structures associated with intense current sheets are limited in all dimensions. The 2D and 3D kinetic particle-in-cell simulations investigate electron-only reconnection, showing a new form of 3D electron-only reconnection with higher reconnection rates.
PHYSICAL REVIEW LETTERS
(2021)
Article
Astronomy & Astrophysics
Tong Shi, Ward Manchester, Enrico Landi, Bart van der Holst, Judit Szente, Yuxi Chen, Gabor Toth, Luca Bertello, Alexander Pevtsov
Summary: This study employs the Alfven Wave Solar Model (AWSoM) to simulate the spectral line emission from a solar active region, demonstrating the effectiveness and applicability of the model through comparisons with observational data.
ASTROPHYSICAL JOURNAL
(2022)
Article
Physics, Fluids & Plasmas
M. Oka, T. D. Phan, M. Oieroset, D. L. Turner, J. F. Drake, X. Li, S. A. Fuselier, D. J. Gershman, B. L. Giles, R. E. Ergun, R. B. Torbert, H. Y. Wei, R. J. Strangeway, C. T. Russell, J. L. Burch
Summary: This study shows that electrons in Earth's magnetotail are energized by the locally averaged electric field magnitude, suggesting the importance of reconnection-driven turbulence. However, the non-thermal power-law component can be small even with a large electric field and significant heating of the bulk population.
PHYSICS OF PLASMAS
(2022)
Article
Astronomy & Astrophysics
Timothy B. Keebler, Gabor Toth, Bertalan Zieger, Merav Opher
Summary: Due to the large size of the Sun's heliosphere and sparse spacecraft measurements, numerical modeling is crucial for predicting solar wind conditions where measurements are lacking. This study utilizes a 2D model to simulate solar wind propagation and creates a dataset of solar wind in the outer heliosphere. The model has been continuously running from 1995 to the present, and the results are available for free online. Validations with observation data demonstrate the effectiveness of the model.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2022)
Article
Geosciences, Multidisciplinary
Xiantong Wang, Yuxi Chen, Gabor Toth
Summary: Magnetospheric sawtooth oscillations are observed during strong and steady solar wind conditions, and our simulation results indicate that these oscillations are generated when the total magnetic flux carried by the solar wind exceeds a certain threshold. The simulated oscillations agree well with observations in terms of period and amplitude, although there are differences in the distribution of magnitude as a function of longitude. Our comparative simulations suggest that kinetic reconnection physics in the magnetotail is a major contributing factor to these sawtooth oscillations.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
Daniel Iong, Yang Chen, Gabor Toth, Shasha Zou, Tuija Pulkkinen, Jiaen Ren, Enrico Camporeale, Tamas Gombosi
Summary: In this study, gradient boosting machines (GBMs) were developed to forecast the SYM-H index multiple hours ahead using different combinations of solar wind and interplanetary magnetic field (IMF) parameters, derived parameters, and past SYM-H values. By quantifying the contributions from each input using Shapley Additive Explanation values, the predictions were found to be consistent with physical understanding and provided insight into the complex relationship between solar wind and Earth's ring current. GBMs were compared with neural networks, showing a statistically significant improvement in root mean squared error over the best published black-box neural network schemes and the Burton equation.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2022)
Article
Astronomy & Astrophysics
Q. Al Shidi, T. Pulkkinen, G. Toth, A. Brenner, S. Zou, J. Gjerloev
Summary: This study uses the Space Weather Modeling Framework to simulate 122 storms from 2010 to 2019 and assesses the model's performance in predicting regional magnetic disturbances. The results show that the predictions are quite accurate at mid-latitudes, but difficulties persist in predicting disturbances at high latitudes.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2022)
Article
Astronomy & Astrophysics
Xiantong Wang, Yuxi Chen, Gabor Toth
Summary: In this study, a MHD-AEPIC model is used to simulate geomagnetic events, and the results are found to be consistent with observations at various scales. The model can effectively identify reconnection sites and incorporate them into the simulation. The results of the model are consistent with observations at global, mesoscale, and kinetic scales.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Dion Li, Yuxi Chen, Chuanfei Dong, Liang Wang, Gabor Toth
Summary: Collisionless magnetic reconnection usually requires expensive kinetic treatment. In this study, we use an innovative MHD-AEPIC model to investigate the interaction of two magnetic flux ropes. By comparing the simulation results among three cases, we find that good agreement can be achieved by incorporating large adaptive PIC regions within the MHD domain, indicating the importance of the coupling between macro-scale MHD and micro-scale kinetic physics in the highly kinetic magnetic island coalescence problem.
