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The standard particle-in-cell algorithm suffers from grid heating. There exists a gridless alternative which bypasses the deposition step and calculates each Fourier mode of the charge density directly from the particle positions. We show…

Plasma Physics · Physics 2019-09-04 Matthew S. Mitchell , Matthew T. Miecnikowski , Gregory Beylkin , Scott E. Parker

We performed a magnetohydrodynamic (MHD) simulation using a nonlinear force-free field (NLFFF) in solar active region 11158 to clarify the dynamics of an X2.2-class solar flare. We found that the NLFFF never shows the drastic dynamics seen…

Solar and Stellar Astrophysics · Physics 2015-06-19 S. Inoue , K. Hayashi , T. Magara , G. S. Choe , Y. D. Park

Inferring interior properties of the Sun from photospheric measurements of the seismic wavefield constitutes the helioseismic inverse problem. Deviations in seismic measurements (such as wave travel times) from their fiducial values…

Solar and Stellar Astrophysics · Physics 2015-06-18 Shravan Hanasoge , Jeroen Tromp

The cause of excess spectral line broadening (non-thermal velocity) is not definitively known, but given its rise before and during flaring, the causal processes hold clues to understanding the triggers for the onset of reconnection and the…

Solar and Stellar Astrophysics · Physics 2024-01-23 James McKevitt , Robert Jarolim , Sarah Matthews , Deborah Baker , Manuela Temmer , Astrid Veronig , Hamish Reid , Lucie Green

The photospheric magnetic field vector is continuously derived from measurements, while reconstruction of the three-dimensional (3D) coronal magnetic field requires modelling with photospheric measurements as a boundary condition. For…

Solar and Stellar Astrophysics · Physics 2022-03-23 I. Chifu , B. Inhester , T. Wiegelmann

We present a Python code for calculating and displaying magnetic field extrapolations from given two-dimensional boundary conditions, specifically from solar surface magnetograms. The code implements analytical magnetohydrostatic models…

Solar and Stellar Astrophysics · Physics 2025-11-13 Lilli Nadol , Thomas Neukirch

A solar flare releases magnetic energy by reconnecting field lines across a current sheet, thereby allowing their relaxation to a lower energy state. The maximum possible energy is released if all field lines relax to a current-free…

Solar and Stellar Astrophysics · Physics 2025-11-03 Drake Osaben , Jiong Qiu , Dana W. Longcope

We compare magnetic field extrapolations from a photospheric magnetogram with the observationally inferred structure of magnetic loops in a newly developed active region. This is the first time that the reconstructed 3D-topology of the…

Astrophysics · Physics 2009-06-25 T. Wiegelmann , A. Lagg , S. K. Solanki , B. Inhester , J. Woch

The prediction of solar flares is typically formulated as a binary classification task, distinguishing events as either Flare (FL) or No-Flare (NF) according to a specified threshold (for example, greater than or equal to C-class, M-class,…

Computer Vision and Pattern Recognition · Computer Science 2025-10-07 Chetraj Pandey , Jinsu Hong , Anli Ji , Rafal A. Angryk , Berkay Aydin

We present observations and magnetic field models of an intermediate filament present on the Sun in August 2012, associated with a polarity inversion line that extends from AR 11541 in the east into the quiet sun at its western end. A…

We report the discovery of torsional Alfv\'enic oscillations in solar flares, which modulate the time evolution of the magnetic free energy $E_f(t)$, while the magnetic potential energy $E_p(t)$ is uncorrelated, and the nonpotential energy…

Solar and Stellar Astrophysics · Physics 2021-06-14 Markus J. Aschwanden , Tongjiang Wang

A new method for reconstruction of coronal magnetic fields as force-free fields (FFFs) is presented. Our method employs poloidal and toroidal functions to describe divergence-free magnetic fields. This magnetic field representation…

Solar and Stellar Astrophysics · Physics 2022-10-04 Sibaek Yi , G. S. Choe , Kyung-Suk Cho , Sami K. Solanki , Jörg Büchner

Magnetic field plays an important role in various solar eruptions like flares, coronal mass ejections, etc. The formation and evolution of characteristic magnetic field topology in solar eruptions are critical problems that will ultimately…

Solar and Stellar Astrophysics · Physics 2023-06-07 Wen He , Qiang Hu , Ju Jing , Haimin Wang , Chaowei Jiang , Sushree S. Nayak , Avijeet Prasad

Lead halide perovskites have emerged as highly efficient solar cell materials. However, to date, the most promising members of this class are polymorphs, in which a wide-band gap $\delta$ phase competes with the photoactive perovskite…

Materials Science · Physics 2024-07-08 C. Vona , M. Dankl , A. Boziki , M. P. Bircher , U. Rothlisberger

The magnetic field permeating the solar atmosphere is generally thought to provide the energy for much of the activity seen in the solar corona, such as flares, coronal mass ejections (CMEs), etc. To overcome the unavailability of coronal…

Solar and Stellar Astrophysics · Physics 2015-06-17 Tilaye Tadesse , T. Wiegelmann , S. Gosain , P. MacNeice , Alexei A. Pevtsov

We present a new approach to factorize and resum the post-Newtonian (PN) waveform for generic equatorial motion to be used within effective-one-body (EOB) based waveform models. The new multipolar waveform factorization improves previous…

General Relativity and Quantum Cosmology · Physics 2022-06-01 Andrea Placidi , Simone Albanesi , Alessandro Nagar , Marta Orselli , Sebastiano Bernuzzi , Gianluca Grignani

We use SDO/HMI and SOLIS/VSM photospheric magnetic field measurements to model the force-free coronal field above a solar active region, assuming magnetic forces to dominate. We take measurement uncertainties caused by, e.g., noise and the…

Solar and Stellar Astrophysics · Physics 2015-06-05 J. K. Thalmann , A. Pietarila , X. Sun , T. Wiegelmann

Optimal Power Flow (OPF) is a core optimization problem in power system operation and planning, aiming to minimize generation costs while satisfying physical constraints such as power flow equations, generator limits, and voltage limits.…

Machine Learning · Computer Science 2025-12-02 Xuezhi Liu

In this study, photospheric vector magnetograms obtained with the Synoptic Optical Long-term Investigations of the Sun survey (SOLIS), are used as boundary conditions to model the three-dimensional nonlinear force-free (NLFF) coronal…

Solar and Stellar Astrophysics · Physics 2015-05-30 Tilaye Tadesse , T. Wiegelmann , B. Inhester , A. Pevtsov

X-ray diffraction, UV-vis absorption and photoluminescence (PL) spectroscopy have been used to study the well-known order-disorder transition (ODT) to the beta phase in poly(9,9-(di n,n-octyl)fluorene)) (PF8) thin film samples through…

Materials Science · Physics 2009-11-07 M. J. Winokur , J. Slinker , D. L. Huber
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