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Response functions to perturbations in the temperature, pressure, microturbulent velocity, and magnetic intensity were calculated for the Stokes parameter profiles of the lines Fe I 525.06, 525.02 and Fe II 614.92 nm. The procedure proposed…

Solar and Stellar Astrophysics · Physics 2012-11-13 V. A. Sheminova

We examine the scattering of acoustic p-mode waves from a thin magnetic fibril embedded in a gravitationally stratified atmosphere. The scattering is mediated through the excitation of slow sausage waves on the magnetic tube, and only the…

Solar and Stellar Astrophysics · Physics 2015-05-28 Bradley W. Hindman , Rekha Jain

Standing sausage modes in flare loops are important for interpreting quasi-periodic pulsations (QPPs) in solar flare lightcurves. We propose an inversion scheme that consistently uses their periods $P$ and damping times $\tau$ to diagnose…

Solar and Stellar Astrophysics · Physics 2015-10-14 Shao-Xia Chen , Bo Li , Ming Xiong , Hui Yu , Ming-Zhe Guo

We present some results obtained from the synthesis of Stokes profiles in small-scale flux tubes with propagating MHD waves. To that aim, realistic flux tubes showing internal structure have been excited with 5 min period drivers, allowing…

Astrophysics · Physics 2008-01-28 E. Khomenko , M. Collados , T. Felipe

Atmospheric trace-gas inversion refers to any technique used to predict spatial and temporal fluxes using mole-fraction measurements and atmospheric simulations obtained from computer models. Studies to date are most often of a…

The Stokes profiles of Fe I lines in the photosphere of the Sun are calculated within the Unno-Beckers-Landi-Dagl`Innocenti theory. Estimates of the magnetic strengthening of the lines were obtained. The changes in the Stokes profiles…

Solar and Stellar Astrophysics · Physics 2022-03-15 V. A. Sheminova

Alfv\'en waves may be generated via mode conversion from fast magneto-acoustic waves near their reflection level in the solar atmosphere, with implications both for coronal oscillations and for active region helio-seismology. In active…

Solar and Stellar Astrophysics · Physics 2015-05-28 Paul S. Cally , Shelley C. Hansen

The Fe I 6173 {\AA} line is widely used in the measurements of vector magnetic fields by instruments including the Helioseismic and Magnetic Imager (HMI). We perform non-local thermodynamic equilibrium calculations of this line based on…

Solar and Stellar Astrophysics · Physics 2018-04-10 Jie Hong , M. D. Ding , Ying Li , Mats Carlsson

The topic of magnetic field diagnostics with the Zeeman effect is currently vividly discussed. There are some testable inversion codes available to the spectropolarimetry community and their application allowed for a better understanding of…

Solar and Stellar Astrophysics · Physics 2016-11-29 M. Derouich

In-situ observations in the Earth's and Saturn's magnetosheaths and in the solar wind reveal the presence of Alfv\'en vortices as intermittent structures in the range of scales from fluid lengths down to few ion lengths. The density and the…

Plasma Physics · Physics 2020-04-16 Dusan Jovanovic , Olga Alexandrova , Milan Maksimovic , Milivoj Belic

Model atmospheres of A and B stars are computed taking into account magnetic line blanketing. These calculations are based on the new stellar model atmosphere code LLModels which implements direct treatment of the opacities due to the…

Astrophysics · Physics 2009-11-10 O. Kochukhov , S. Khan , D. Shulyak

In a previous paper, we argued that the inversion of Stokes profiles applied to spectropolarimetric observations of the solar internetwork yield unrealistically large values of the inclination of the magnetic field vector ($\gamma$). This…

Solar and Stellar Astrophysics · Physics 2015-06-11 J. M. Borrero , P. Kobel

The goal of this study is to explore a novel method for the solar photospheric magnetic field diagnostics using Stokes V widths of different magnetosensitive Fe~I spectral lines. We calculate Stokes I and V profiles of several Fe I lines…

Solar and Stellar Astrophysics · Physics 2020-01-29 M. Gordovskyy , S. Shelyag , P. K. Browning , V. G. Lozitsky

It has been shown recently that magnetic twist and axisymmetric MHD modes are ubiquitous in the solar atmosphere and therefore, the study of resonant absorption for these modes have become a pressing issue as it can have important…

Solar and Stellar Astrophysics · Physics 2017-06-30 Ioannis Giagkiozis , Marcel Goossens , Gary Verth , Viktor Fedun , Tom Van Doorsselaere

For materials near the phase boundary between weak and strong topological insulators (TIs), their band topology depends on the band alignment, with the inverted (normal) band corresponding to the strong (weak) TI phase. Here, taking the…

Mesoscale and Nanoscale Physics · Physics 2020-07-29 Y. Jiang , J. Wang , T. Zhao , Z. L. Dun , Q. Huang , X. S. Wu , M. Mourigal , H. D. Zhou , W. Pan , M. Ozerov , D. Smirnov , Z. Jiang

The Helioseismic and Magnetic Imager (HMI) onboard NASA's Solar Dynamics Observatory (SDO) produces estimates of the photospheric magnetic field which are a critical input to many space weather modelling and forecasting systems. The…

We present a new library of synthetic spectra based on the stellar atmosphere code PHOENIX. It covers the wavelength range from 500{\AA} to 55000{\AA} with a resolution of R=500000 in the optical and near IR, R=100000 in the IR and…

Solar and Stellar Astrophysics · Physics 2012-03-12 T. -O. Husser , S. Kamann , S. Dreizler , Peter. H. Hauschildt

Reduced fluid models including electron inertia and ion finite Larmor radius corrections are derived asymptotically, both from fluid basic equations and from a gyrofluid model. They apply to collisionless plasmas with small ion-to-electron…

Plasma Physics · Physics 2022-02-02 Thierry Passot , Pierre-Louis Sulem , Emanuele Tassi

The inference of the underlying state of the plasma in the solar chromosphere remains extremely challenging because of the nonlocal character of the observed radiation and plasma conditions in this layer. Inversion methods allow us to…

Solar and Stellar Astrophysics · Physics 2019-03-06 J. de la Cruz Rodríguez , J. Leenaarts , S. Danilovic , H. Uitenbroek

Observations suggest that twisted magnetic flux tubes are ubiquitous in the Sun's atmosphere. The main aim of this work is to advance the study of axisymmetric modes of magnetic flux tubes by modeling both twisted internal and external…

Solar and Stellar Astrophysics · Physics 2017-06-30 Ioannis Giagkiozis , Viktor Fedun , Robart Erdeliy , Gary Verth