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We report the systematic detection of magnetic fields in massive (M > 5 M$_\odot$) late-type supergiants, using spectropolarimetric observations obtained with ESPaDOnS at the Canada-France-Hawaii Telescope. Our observations reveal…

Solar and Stellar Astrophysics · Physics 2015-05-19 Jason H. Grunhut , Gregg A. Wade , David A. Hanes , Evelyne Alecian

The study of the linear and circular polarization in AGN allows one to gain detailed information about the properties of the magnetic fields in these objects. However, especially the observation of circular polarization (CP) with…

Instrumentation and Methods for Astrophysics · Physics 2015-05-13 E. Cenacchi , A. Kraus , A. Orfei , K. -H. Mack

Received: 1st December 2018; Accepted: 18th February 2019; Published: 1st April 2019 Abstract: The calculated filling factors (FFs) for a feature reflect the fraction of the solar disc covered by that feature, and the assignment of…

Solar and Stellar Astrophysics · Physics 2019-04-03 Amro F. Alasta , Abdrazag Algamudi , Fatma Almesrati , Mustapha Meftah , Rami Qahwaji

Magnetic Bright Points (MBPs) in the internetwork are among the smallest objects in the solar photosphere and appear bright against the ambient environment. An algorithm is presented that can be used for the automated detection of the MBPs…

Solar and Stellar Astrophysics · Physics 2015-05-13 P. J. Crockett , D. B. Jess , M. Mathioudakis , F. P. Keenan

Realizing high-throughput aberration-corrected Scanning Transmission Electron Microscopy (STEM) exploration of atomic structures requires rapid tuning of multipole probe correctors while compensating for the inevitable drift of the optical…

Machine Learning · Computer Science 2026-01-28 Utkarsh Pratiush , Austin Houston , Richard Liu , Gerd Duscher , Sergei Kalinin

We describe and demonstrate a technique for correcting direction dependent artifacts due to asymmetries in antenna patterns and differences among antennas used in radio interoferometric imaging. The technique can correct images in all…

Instrumentation and Methods for Astrophysics · Physics 2021-10-13 W. D. Cotton , T. Mauch

Since the first detection of gravitational waves by the LIGO/VIRGO team, the related research field has attracted more attention. The spinning compact binaries system, as one of the gravitational-wave sources for broadband laser…

General Relativity and Quantum Cosmology · Physics 2022-12-21 Junjie Luo , Jie Feng , Hong-Hao Zhang , Weipeng Lin

Strong, globally-organized magnetic fields are found for a small fraction of O, B, and A stars. At the same time, many theoretical and indirect observational studies suggested ubiquitous presence of weak localized magnetic fields at the…

Solar and Stellar Astrophysics · Physics 2015-06-15 O. Kochukhov , N. Sudnik

In this paper, we introduce the concept of Density-Balanced Subset in a matroid, in which independent sets can be sampled so as to guarantee that (i) each element has the same probability to be sampled, and (ii) those events are negatively…

Data Structures and Algorithms · Computer Science 2023-08-15 François Sellier

Estimating the ratio of two probability densities from finitely many samples, is a central task in machine learning and statistics. In this work, we show that a large class of kernel methods for density ratio estimation suffers from error…

Machine Learning · Computer Science 2024-06-04 Lukas Gruber , Markus Holzleitner , Johannes Lehner , Sepp Hochreiter , Werner Zellinger

We present test results on the simultaneous inversion of the Stokes profiles of the He I lines at 587.6 nm (D_3) and 1083.0 nm in prominences (90-deg scattering). We created datasets of synthetic Stokes profiles for the case of quiescent…

Instrumentation and Methods for Astrophysics · Physics 2009-09-28 R. Casini , A. Lopez Ariste , F. Paletou , L. Leger

The standard methods of the magnetic field measurement, based on an analysis of the relation between the Stokes $V$-parameter and the first derivative of the total line profile intensity, were modified by applying a linear integral operator…

Solar and Stellar Astrophysics · Physics 2015-06-15 A. F. Kholtygin

We aim at demonstrating the capabilities of a newly developed method for determining electric currents in the solar photosphere. We employ three-dimensional radiative magneto-hydrodynamic (MHD) simulations to produce synthetic Stokes…

Solar and Stellar Astrophysics · Physics 2021-12-22 A. Pastor Yabar , J. M. Borrero , C. Quintero Noda , B. Ruiz Cobo

Magnetic field diagnostics of the transition region from the chromosphere to the corona faces us with the problem that one has to apply extreme UV spectro-polarimetry. While for coronal diagnostic techniques already exist through infrared…

Solar and Stellar Astrophysics · Physics 2013-03-11 H. Peter

Purpose: Field monitoring measures field perturbations, which can be accounted for during image reconstructions. In certain field monitoring environments, significant phase deviations can arise far from isocenter due to the finite extent of…

Medical Physics · Physics 2023-01-25 Paul I. Dubovan , Kyle M. Gilbert , Corey A. Baron

Context. For accurately measuring intensities and determining magnetic field strengths of small-scale solar (magnetic) structure, knowledge of and compensation for the point spread function is crucial. For images recorded with the Swedish…

Instrumentation and Methods for Astrophysics · Physics 2015-05-19 G. B. Scharmer , M. G. Löfdahl , T. I. M. van Werkhoven , J. de la Cruz Rodriguez

We propose a new method for absolute momentum calibration of magnetic spectrometers used in nuclear physics, using the time-of-flight (TOF), differences of pairs of particles with different masses. In cases where the flight path is not…

We present high-precision spectro-polarimetric data with high spatial resolution (0.4$''$) of the very quiet Sun at 1.56$\mu$m obtained with the GREGOR telescope to shed some light on this complex magnetism. Half of our observed quiet-Sun…

We show how to properly extract the local charge order in two-dimensional materials from scanning tunneling microscopy/spectroscopy (STM/STS) measurements. When the charge order presents spatial variations at the atomic scale inside the…

We have investigated via two-dimensional relativistic MHD simulations the long-term evolution of turbulence created by a relativistic shock propagating through an inhomogeneous medium. In the postshock region, magnetic field is strongly…

High Energy Astrophysical Phenomena · Physics 2014-03-05 Yosuke Mizuno , Martin Pohl , Jacek Niemiec , Bing Zhang , Ken-Ichi Nishikawa , Philip E. Hardee