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The three Mn I lines at 17325, 17339 and 17349 \AA~are among the 25 strongest lines ($\log(gf)>0.5$) in the H-band. They are all heavily broadened due to hyperfine structure and the profiles of these lines have so far not been understood.…

Solar and Stellar Astrophysics · Physics 2015-06-19 Martin Andersson , Jon Grumer , Nils Ryde , Richard Blackwell-Whitehead , Roger Hutton , Yaming Zou , Per Jönsson , Tomas Brage

(Edited for length) The Zeeman effect is the only observational technique available to measure directly the strength of magnetic fields in regions of star formation. We review the physics of the Zeeman effect and its practical use in both…

Astrophysics of Galaxies · Physics 2019-11-15 Richard M. Crutcher , Athol J. Kemball

Context: The presence of a turbulent magnetic field in the quiet Sun has been unveiled observationally using different techniques. The magnetic field is quasi-isotropic and has field strengths weaker than 100G. It is pervasive and may host…

Solar and Stellar Astrophysics · Physics 2016-11-26 A. López Ariste , A. Sainz Dalda

We analyze Fe I 630 nm observations of the quiet Sun at disk center taken with the spectropolarimeter of the Solar Optical Telescope aboard the Hinode satellite. A significant fraction of the scanned area, including granules, turns out to…

Although the magnetic fields in the quiet Sun account for the majority of the magnetic energy in the solar photosphere, inferring their exact spatial distribution, origin, and evolution poses an important challenge because the signals lie…

Solar and Stellar Astrophysics · Physics 2024-10-03 Elias Ebert , Ivan Milic , Juan Manuel Borrero

We present first quantitative results of the surface magnetic field measurements in selected M-dwarfs based on detailed spectra synthesis conducted simultaneously in atomic and molecular lines of the FeH Wing-Ford $F^4\,\Delta-X^4\,\Delta$…

Solar and Stellar Astrophysics · Physics 2015-05-19 D. Shulyak , A. Reiners , S. Wende , O. Kochukhov , N. Piskunov , A. Seifahrt

The infrared Mg I lines near 12 microns are a pair of emission lines which are magnetically sensitive and have been used to measure solar magnetic fields. Here we calculate the response of the Mg I 12.32 $\mu$m line during a flare and find…

Solar and Stellar Astrophysics · Physics 2020-08-04 Jie Hong , Xianyong Bai , Ying Li , M. D. Ding , Yuanyong Deng

The uncertainty about a possible correlation between strength and inclination of the magnetic field and the continuum intensity of the sunspot penumbral fine-structure has been removed by a detailed analysis of a spatially very high…

Solar and Stellar Astrophysics · Physics 2016-05-26 E. Wiehr

This paper investigates the distribution of linear polarization signals in the quiet Sun internetwork using ultra-deep spectropolarimetric data. We reduce the noise of the observations as much as is feasible by adding single-slit…

Solar and Stellar Astrophysics · Physics 2012-09-04 L. R. Bellot Rubio , D. Orozco Suárez

The morphology of circular polarisation profiles from solar spectropolarimetric observations encode information about the magnetic field strength, inclination, and line-of-sight velocity gradients. Previous studies used manual methods or…

Solar and Stellar Astrophysics · Physics 2025-05-21 Ryan James Campbell , Mihalis Mathioudakis , Carlos Quintero Noda , Peter Keys , David Orozco Suárez

Aims. We examined the capabilities of methods based on the weak-field approximation and line bisectors to extract fast and reliable information about the height stratification of the magnetic field and line-of-sight velocities,…

Solar and Stellar Astrophysics · Physics 2025-03-18 A. L. Siu-Tapia , L. R. Bellot Rubio , D. Orozco Suárez

Characteristics of the depression contribution functions are studied for the Stokes line profiles formed in a magnetic field. The form of the depression functions depends mainly on the strength of splitting and the Zeeman component…

Solar and Stellar Astrophysics · Physics 2012-10-16 V. A. Sheminova

Global magnetic fields of active solar-like stars are nowadays routinely detected with spectropolarimetric measurements and are mapped with Zeeman-Doppler imaging (ZDI). However, due to the cancellation of opposite field polarities,…

Solar and Stellar Astrophysics · Physics 2020-03-25 O. Kochukhov , T. Hackman , J. J. Lehtinen , A. Wehrhahn

The Helioseismic and Magnetic Imager (HMI) aboard the Solar Dynamics Observatory (SDO) observes the Sun at the Fe I 6173 {\AA} line and returns full-disk maps of line-of-sight (LOS) observables including the magnetic flux density,…

Solar and Stellar Astrophysics · Physics 2015-02-20 Daniel P. Cohen , Serena Criscuoli , Laurel Farris , Alexandra Tritschler

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 main-sequence mercury-manganese (HgMn) stars are known to exhibit large overabundances of exotic elements and, similar to magnetic Ap/Bp stars, are spectrum variables, implying the presence of an inhomogeneous element distribution over…

Solar and Stellar Astrophysics · Physics 2020-04-29 S. Hubrig , S. P. Jarvinen , H. Korhonen , I. Ilyin , M. Schöller , E. Niemczura , S. D. Chojnowski

Recent observations with the HINODE satellite have found abundant horizontal magnetic fields in the internetwork quiet Sun. We compare the results on the horizontal fields with ground-based observations. We obtained 30 sec-integrated data…

Solar and Stellar Astrophysics · Physics 2015-05-13 C. A. R. Beck , R. Rezaei

The physical conditions of the solar photosphere change on very small spatial scales both horizontally and vertically. Such a complexity may pose a serious obstacle to the accurate determination of solar magnetic fields. We examine the…

Solar and Stellar Astrophysics · Physics 2015-05-19 D. Orozco Suárez , L. R. Bellot Rubio , A. Vögler , J. C. Del Toro Iniesta

The dynamical state of star-forming molecular clouds cannot be understood without determining the structure and strength of their magnetic fields. Measurements of polarized far-infrared radiation from thermally aligned dust grains are used…

Astrophysics · Physics 2009-11-06 F. Heitsch , E. G. Zweibel , M. -M. Mac Low , P. S. Li , M. L. Norman

We describe a new form of small-scale magnetic flux emergence in the quiet Sun. This process seems to take vertical magnetic fields from the solar interior to the photosphere, where they appear above granular convection cells. High-cadence…

Astrophysics · Physics 2009-11-13 D. Orozco Suarez , L. R. Bellot Rubio , J. C. del Toro Iniesta , S. Tsuneta