Article
Multidisciplinary Sciences
Savvas Raptis, Tomas Karlsson, Andris Vaivads, Craig Pollock, Ferdinand Plaschke, Andreas Johlander, Henriette Trollvik, Per-Arne Lindqvist
Summary: Shocks, a powerful particle accelerator in nature, have been linked to relativistic electron acceleration and cosmic rays. In this study, the authors used MMS to observe high-speed downstream flows (jets) generated at the Earth's bow shock as a direct consequence of shock reformation.
NATURE COMMUNICATIONS
(2022)
Article
Astronomy & Astrophysics
Daniel Schmid, Yasuhito Narita
Summary: Magnetohydrodynamic (MHD) shocks are commonly found in space and astrophysical systems. This study aims to understand the mathematical structure of the MHD Rankine-Hugoniot relation when only magnetic field data are available, and proposes a diagnostic tool to constrain shock parameters based on this information.
ASTROPHYSICAL JOURNAL
(2023)
Article
Physics, Fluids & Plasmas
Rajesh Kumar, Youichi Sakawa, Takayoshi Sano, Leonard N. K. Dohl, Nigel Woolsey, Alessio Morace
Summary: Intense laser-plasma interactions can generate two electrostatic collisionless shocks at distinct longitudinal positions when driven by a linearly polarized laser in a multicomponent plasma according to two-dimensional particle-in-cell calculations. These shocks exhibit a power-law dependence on the normalized laser vector potential a(0) and accelerate ions to different velocities, suggesting the presence of electrostatic ion two-stream instability. Such particle acceleration processes are common in space and astrophysics, offering exciting possibilities for laboratory studies.
Article
Astronomy & Astrophysics
Vyacheslav Olshevsky, Yuri Khotyaintsev, Ahmad Lalti, Andrey Divin, Gian Luca Delzanno, Sven Anderzen, Pawel Herman, Steven W. D. Chien, Levon Avanov, Andrew P. Dimmock, Stefano Markidis
Summary: The properties of ion sky maps produced by Dual Ion Spectrometers from the Fast Plasma Investigation were investigated, and a convolutional neural network classifier with >98% accuracy was trained to predict four regions crossed by the Magnetospheric Multiscale Mission. The classifier was used to detect mixed plasma regions, identify magnetopause crossings, and reveal regions prone to magnetic reconnection, demonstrating fast and efficient data processing capabilities for classification within the entire MMS database.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Geosciences, Multidisciplinary
Savvas Raptis, Tomas Karlsson, Andris Vaivads, Martin Lindberg, Andreas Johlander, Henriette Trollvik
Summary: In this study, the properties of a high-speed plasma jet downstream of the Quasi-parallel bow shock were investigated using high-resolution data. It was found that the jet is a kinetic structure with highly variable velocity distributions. The jet consists of a cold/fast component and a hotter/slower background population, and it shows similarities to upstream solar wind beams.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Physics, Multidisciplinary
Swarnima Singh, P. Bandyopadhyay, Krishan Kumar, A. Sen
Summary: The study presents the first observations of a square lattice formation in a monodisperse complex plasma system, and successfully achieves configurational transition by carefully controlling the system's specific parameters. Some theoretical insights into the transition process are provided through molecular dynamics simulations.
PHYSICAL REVIEW LETTERS
(2022)
Article
Astronomy & Astrophysics
Martijn de Vries, Roger W. Romani
Summary: New X-ray and optical observations provide insights into the X-ray filament of the gamma-ray pulsar PSR J2030+4415. The comparison of the evolution of the associated bow shock and its velocity structure improves our understanding of the pulsar's distance and spin axis. The multi-bubble shock structure suggests that the bow shock was compressed when the pulsar broke through it, allowing high-energy particles to escape and form the filament. The narrow filament and its projected length indicate rapid particle propagation and spectral evolution.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
C. Signoles, M. Persson, Y. Futaana, S. Aizawa, N. Andre, S. Bergman, A. Fedorov, V. Lindwall, N. Martinez, C. Mazelle, S. Rojas Mata, A. Wolff, T. L. Zhang
Summary: Investigations of the boundaries and their variability of the induced magnetosphere on Venus can help us understand the solar wind's effect on Venus and unmagnetized planets. Using data from Venus Express, this study finds that the location of the bow shock is mainly influenced by the solar cycle and dynamic pressure, while the ion composition boundary shows clear changes during solar maximum but no clear trends during solar minimum.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Michael Gedalin, Nikolai V. Pogorelov, Vadim Roytershteyn
Summary: In a collisionless shock, the energy of directed flow is converted into heating, acceleration of charged particles, and magnetic compression. The behavior of ion distribution differs in low-Mach number and higher-Mach number shocks, with ion reflection becoming important in the latter. Rippling, which develops with the increase of Mach number, affects ion dynamics, resulting in broader and more diffuse ion distributions in phase space. Rippling also generates backstreaming ions that are absent in the planar stationary case.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
O. W. Roberts, R. Nakamura, V. N. Coffey, D. J. Gershman, M. Volwerk, A. Varsani, B. L. Giles, J. C. Dorelli, C. Pollock
Summary: This study compared plasma measurements taken by MMS's FPI and OMNI near the Earth-Sun L1 Lagrangian point, highlighting differences in ion density, temperature, and velocity under different measurement modes. Suggestions were made for interpreting and applying these parameters effectively.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Terry Z. Liu, Vassilis Angelopoulos, Andrew Vu, Hui Zhang
Summary: In the ion foreshock, hot flow anomalies (HFAs) and foreshock bubbles (FBs) are two types of foreshock transients that have significant fluctuations. They are formed due to the interaction between foreshock ions and solar wind discontinuities. The direction of the foreshock ion-driven current and the changes in magnetic field strength behind the discontinuity determine the formation of these transients. This study aims to predict the formation of HFAs and FBs by deriving analytical equations to estimate the foreshock ion-driven current direction.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Mechanics
Manuel Nunez
Summary: The study finds that the jump in conductivity across a magnetohydrodynamic bow shock leads to the inaccuracy of the classical Rankine-Hugoniot conditions. An approximate solution to the MHD equations can be obtained by considering an asymptotic expansion in powers of the conductivity upstream of the shock and resistivity downstream. Furthermore, the study discovers that in specific solutions, velocity and magnetic field are locally aligned behind the shock.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2022)
Article
Astronomy & Astrophysics
M. V. D. Silveira, D. G. Sibeck
Summary: Tracking the location and motion of the bow shock and magnetopause can reveal important information about the solar wind-magnetosphere interaction. This paper presents a method to detect and track the magnetopause and bow shock motion using multipoint in situ observations of the magnetosheath. The results show that the velocity gradient method can be used to accurately determine the location of the magnetopause and bow shock based on two-spacecraft measurements at the subsolar magnetosheath, except when conditions are very turbulent or downstream of the quasi-parallel shock.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Computer Science, Artificial Intelligence
Ahmad Naeem, Tayyaba Anees, Khawaja Tehseen Ahmed, Rizwan Ali Naqvi, Shabir Ahmad, Taegkeun Whangbo
Summary: This paper proposes a novel deep learning technique for image retrieval, which combines convolutional neural network with auto-correlation, gradient computation, and other techniques to achieve highly accurate results. The experiments demonstrate outstanding performance of the proposed method on various datasets.
COMPLEX & INTELLIGENT SYSTEMS
(2023)
Article
Biochemistry & Molecular Biology
Yutong Liu, Mengting Li, Jinlei Yu, Ao Ma, Jie Wang, Dae-Jin Yun, Zheng-Yi Xu
Summary: The salinization of irrigated land reduces agricultural productivity. A mutation in OsHKT1;5 leads to a salt stress-sensitive phenotype, caused by a decrease in transcripts. This phenotype is due to the loss of function of OsDNAJ15, which encodes a plasma membrane-localized heat shock protein 40 (Hsp40).
JOURNAL OF INTEGRATIVE PLANT BIOLOGY
(2023)
