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Assuming that the interchange convection of magnetic flux elements is the physical cause for the existence of filamentary penumbrae in sunspots, we investigate the behavior of an individual fibril embedded in the deep penumbra. The fibril…

Astrophysics · Physics 2016-08-30 R. Schlichenmaier , K. Jahn , H. U. Schmidt

We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited scans of the Fe I 617.3…

Solar and Stellar Astrophysics · Physics 2015-06-23 S. Esteban Pozuelo , L. R. Bellot Rubio , J. de la Cruz Rodriguez

This paper is concerned with the inverse problem of reconstructing a small object from far field measurements. The inverse problem is severally ill-posed because of the diffraction limit and low signal to noise ratio. We propose a novel…

Analysis of PDEs · Mathematics 2017-04-18 Habib Ammari , Matias Ruiz , Sanghyeon Yu , Hai Zhang

Spectroscopy in the infrared provides a means to assess important properties of the plasma in gaseous nebulae. We present some of our own work that illustrates the need for interactions between the themes of this conference - astronomical…

The image reconstruction problem of the tomographic imaging technique magnetic particle imaging (MPI) requires the solution of a linear inverse problem. One prerequisite for this task is that the imaging operator that describes the mapping…

Computational Physics · Physics 2019-07-12 Tobias Kluth , Patryk Szwargulski , Tobias Knopp

We propose a kernel-spectral embedding algorithm for learning low-dimensional nonlinear structures from high-dimensional and noisy observations, where the datasets are assumed to be sampled from an intrinsically low-dimensional manifold and…

Machine Learning · Statistics 2023-07-07 Xiucai Ding , Rong Ma

The parabolic structure of the secondary or conjugate spectra of pulsars is often the result of isolated one-dimensional (or at least highly anisotropic) lenses in the ISM. The curvature of these features contains information about the…

Instrumentation and Methods for Astrophysics · Physics 2023-07-11 Daniel Baker , Walter Brisken , Marten H. van Kerkwijk , Robert Main , Ue-Li Pen , Tim Sprenger , Olaf Wucknitz

We present the observations of penumbra like features (PLFs) near a polarity inversion line (PIL) of flaring region. The PIL is located at the moat boundary of active region (NOAA 10960). The PLFs appear similar to sunspot penumbrae in…

Solar and Stellar Astrophysics · Physics 2015-10-21 B. Ravindra , Sanjay Gosain

This paper investigates the shape reconstructions of sub-wavelength objects from near-field measurements in transverse electromagnetic scattering. This geometric inverse problem is notoriously ill-posed and challenging. We develop a novel…

Mathematical Physics · Physics 2023-05-03 M. H. Ding , H. Y. Liu , G. H. Zheng

Shape matching is a fundamental task in computer graphics and vision, with deep functional maps becoming a prominent paradigm. However, existing methods primarily focus on learning informative feature representations by constraining…

Computer Vision and Pattern Recognition · Computer Science 2026-03-26 Feifan Luo , Hongyang Chen

We report on recent results from our successful and pioneering observational program with ALMA to study emerging ultracom pact HII regions of pre-Planetary Nebulae (pPNe) using mm-wavelength recombination lines (mRRLs) as new optimal…

Solar and Stellar Astrophysics · Physics 2025-10-08 C. Sánchez Contreras , D. Tafoya , J. P. Fonfría , J. Alcolea , A. Castro-Carrizo , V. Bujarrabal

Using high-resolution spectropolarimetric data acquired by \textit{IBIS}, as well as \textit{SDO}/HMI observations, we studied the penumbra formation in AR NOAA 11490 and in a sample of twelve ARs appeared on the solar disk on 2011 and…

Solar and Stellar Astrophysics · Physics 2019-07-17 M. Murabito , P. Romano , F. Zuccarello , S. L. Guglielmino

The Planetary Nebula Spectrograph is a dedicated instrument for measuring radial velocity of individual Planetary Nebulae (PNe) in galaxies. This new instrument is providing crucial data with which to probe the structure of dark halos in…

We study the evolution of the fine-structure constant, $\alpha$, induced by non-linear density perturbations in the context of the simplest class of quintessence models with a non-minimal coupling to the electromagnetic field, in which the…

Astrophysics · Physics 2009-11-13 P. P. Avelino , C. J. A. P. Martins , J. Menezes , C. Santos

Magnetic Resonance Elastography (MRE) has become an essential tool in assessing the mechanical properties of soft tissues in-vivo, prompting significant progress in new inversion algorithms. This creates a need for a benchmarking framework…

Numerical Analysis · Mathematics 2026-04-06 Yashasvi Verma , Jakob Schattenfroh , Ingolf Sack , Silvia Budday , Paul Steinmann , Luca Heltai

The spins of binary black holes measured with gravitational waves provide insights about the formation, evolution, and dynamics of these systems. However, interpreting these measurements-especially for heavy black holes-remains an open…

General Relativity and Quantum Cosmology · Physics 2025-08-01 Karen Kang , Simona J. Miller , Katerina Chatziioannou , Deborah Ferguson

We present a novel method to image spin properties of spintronic systems using the spatially confined field of a scanned micromagnetic probe, in conjunction with existing electrical or optical global spin detection schemes. It is thus…

Mesoscale and Nanoscale Physics · Physics 2011-01-18 V. P. Bhallamudi , A. J. Berger , D. E. Labanowski , D. Stroud , P. C. Hammel

We study the structure and evolution of the horizontal proper motions in a regular sunspot penumbra, very close to the solar disc center, in active region NOAA 11092 using a 48 min time sequences of blue continuum images recorded by…

Solar and Stellar Astrophysics · Physics 2024-05-14 Hashem Hamedivafa

The identification of material parameters occurring in constitutive models has a wide range of applications in practice. One of these applications is the monitoring and assessment of the actual condition of infrastructure buildings, as the…

Machine Learning · Computer Science 2023-06-14 David Anton , Henning Wessels

Sunspot engravings made in the Maunder minimum are used to evaluate the fine structure of sunspots. Based on 78 images of the full solar disk and 77 images of individual sunspots, we have evaluated the ratio of penumbral-to-umbral area…

Solar and Stellar Astrophysics · Physics 2025-06-24 Nadezhda Zolotova , Mikhail Vokhmyanin
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