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Related papers: Spectropolarimetric NLTE inversion code SNAPI

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Aiming at obtaining detailed information of surface environment of Earth analogs, Kawahara & Fujii (2011) proposed an inversion technique of annual scattered light curves named the spin-orbit tomography (SOT), which enables one to sketch a…

Earth and Planetary Astrophysics · Physics 2015-06-04 Yuka Fujii , Hajime Kawahara

A method for the determination of integrated longitudinal stellar fields from low-resolution spectra is the so-called slope method, which is based on the regression of the Stokes V signal against the first derivative of Stokes I. Here we…

Solar and Stellar Astrophysics · Physics 2017-08-18 C. Scalia , F. Leone , M. Gangi , M. Giarrusso , M. J. Stift

An inverse problem in spectroscopy is considered. The objective is to restore the discrete spectrum from observed spectrum data, taking into account the spectrometer's line spread function. The problem is reduced to solution of a system of…

Numerical Analysis · Mathematics 2017-01-23 Valery Sizikov , Denis Sidorov

Scattering line polarization and the Hanle effect are among the most important mechanisms for diagnostics of the solar and stellar atmospheres. The fact that real stellar atmospheres are horizontally inhomogeneous makes the spectral…

Solar and Stellar Astrophysics · Physics 2015-11-02 Jiří Štěpán

Electromagnetic scattering and absorption by material particles is a fundamental physical problem with a broad range of applications, going from laboratory experiments, biology and material sciences, all the way up to environmental studies…

Instrumentation and Methods for Astrophysics · Physics 2026-02-06 G. La Mura , G. Mulas , G. Aresu , M. A. Iatì , C. Cecchi-Pestellini , S. Rezaei , R. Saija

Inferring the three-dimensional (3D) solar atmospheric structures from observations is a critical task for advancing our understanding of the magnetic fields and electric currents that drive solar activity. In this work, we introduce a…

The National Science Foundation's Daniel K. Inouye Solar Telescope (DKIST) will provide high-resolution, multi-line spectropolarimetric observations that are poised to revolutionize our understanding of the Sun. Given the massive data…

Modern surveys often deliver hundreds of thousands of stellar spectra at once, which are fit to spectral models to derive stellar parameters/labels. Therefore, the technique of Amortized Neural Posterior Estimation (ANPE) stands out as a…

Solar and Stellar Astrophysics · Physics 2023-12-12 Keming Zhang , Tharindu Jayasinghe , Joshua S. Bloom

{We aim to demonstrate the effect of atmospheric inhomogeneities on the emergent specific intensity and radiation flux of a spectral line radiation.} {We self-consistently solve the NLTE problem for a two-level atom in a 3D atmosphere using…

Solar and Stellar Astrophysics · Physics 2019-01-08 A. Tichý , J. Kubát

Remarkable mathematical properties of the integrable nonlinear Schr\"odinger equation (NLSE) can offer advanced solutions for the mitigation of nonlinear signal distortions in optical fibre links. Fundamental optical soliton, continuous and…

Exactly Solvable and Integrable Systems · Physics 2017-06-07 L. L. Frumin , A. A. Gelash , S. K. Turitsyn

We investigate the diagnostic potential of the spectral lines at 850 nm for understanding the magnetism of the lower atmosphere. For that purpose, we use a newly developed 3D simulation of a chromospheric jet to check the sensitivity of the…

Both NASA's Solar Dynamics Observatory (SDO) and the JAXA/NASA Hinode mission include spectropolarimetric instruments designed to measure the photospheric magnetic field. SDO's Helioseismic and Magnetic Imager (HMI) emphasizes full-disk…

We analyze spectropolarimetric sunspot umbra observations taken in the near-infrared Si i 1082.7 nm line taking NLTE effects into account. The data were obtained with the GRIS instrument installed at the German GREGOR telescope. A point…

Solar and Stellar Astrophysics · Physics 2017-11-22 D. Orozco Suarez , C. Quintero Noda , B. Ruiz Cobo , M. Collados Vera

Accurately known stellar lithium abundances may be used to shed light on a variety of astrophysical phenomena such as Big Bang nucleosynthesis, radial migration, ages of stars and stellar clusters, and planet engulfment events. We present a…

Solar and Stellar Astrophysics · Physics 2020-10-30 E. Wang , T. Nordlander , M. Asplund , A. M. Amarsi , K. Lind , Y. Zhou

We describe S2LET, a fast and robust implementation of the scale-discretised wavelet transform on the sphere. Wavelets are constructed through a tiling of the harmonic line and can be used to probe spatially localised, scale-depended…

Information Theory · Computer Science 2013-10-29 B. Leistedt , J. D. McEwen , P. Vandergheynst , Y. Wiaux

The Milne-Eddington approximation provides an analytic and simple solution to the radiative transfer equation. It can be easily implemented in inversion codes that are used to fit spectro-polarimetric observations to infer average values of…

Solar and Stellar Astrophysics · Physics 2022-03-23 A. J. Dorantes-Monteagudo , A. L. Siu-Tapia , C. Quintero Noda , D. Orozco Suárez

We present a new radiative transfer code for axi-symmetric stellar atmospheres and compare test results against 1D and 2D models with and without velocity fields. The code uses the short characteristic method with modifications to handle…

Astrophysics · Physics 2009-11-11 J. Zsargo , D. J. Hillier , L. N. Georgiev

We report the publication of treams, a new software for electromagnetic scattering computations based on the T-matrix method. Besides conventional T-matrix calculations for individual scatterers and finite clusters of particles, a unique…

Computational Physics · Physics 2023-09-07 Dominik Beutel , Ivan Fernandez-Corbaton , Carsten Rockstuhl

Nanostructures, such a quantum dots or nanoparticles, made of three-dimensional topological insulators (3DTIs) have been recently attracting increasing interest, especially for their optical properties. In this paper we calculate the energy…

Mesoscale and Nanoscale Physics · Physics 2022-11-23 Michele Governale , Fabio Taddei

The spectral flux density of stars can indicate their atmospheric physical properties. A detector can obtain any band flux density at the design stage. However, the band flux density is confirmed and fixed in the process of operation…

Instrumentation and Methods for Astrophysics · Physics 2018-09-26 Chuanxin Zhang , Yuan Yuan , Zhaoyang Yu , Fuqiang Wang , Heping Tan