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A large set of high precision full-Stokes spectropolarimetric observations of the He-D3 line in spicules has been recorded with the ZIMPOL polarimeter at the Gregory-Coude Telescope in Locarno. The observational technique allow us to obtain…

Solar and Stellar Astrophysics · Physics 2010-11-26 R. Ramelli , M. Bianda , L. Merenda , J. Trujillo Bueno

Magnetic fields in cool stars can be investigated by measuring Zeeman line broadening and polarization in atomic and molecular lines. Similar to the Sun, these fields are complex and height-dependent. Many molecular lines dominating M-dwarf…

Solar and Stellar Astrophysics · Physics 2019-09-11 N. Afram , S. V. Berdyugina

Narrow band imaging in the G-band is commonly used to trace the small magnetic field concentrations of the Sun, although the mechanism that makes them bright has remained unclear. We carry out LTE syntheses of the G-band in an assorted set…

Astrophysics · Physics 2009-11-06 J. Sánchez Almeida , A. Asensio Ramos , J. Trujillo Bueno , J. Cernicharo

The method of solar magnetic field calibration for the filter-based magnetograph is normally the linear calibration method under weak-field approximation that cannot generate the strong magnetic field region well due to the magnetic…

Solar and Stellar Astrophysics · Physics 2021-02-10 Jingjing Guo , Xianyong Bai , Yuanyong Deng , Hui Liu , Jiaben Lin , Jiangtao Su , Xiao Yang , Kaifan Ji

Detection of hard X-ray spectrum (spectral index < 2) from the kilo-parsec scale jet of active galactic nuclei cannot be accounted to the synchrotron emission mechanism from the electron distribution responsible for the radio/optical…

High Energy Astrophysical Phenomena · Physics 2023-08-02 Amal A. Rahman , S. Sahayanathan , Malik Zahoor , P. A Subha

Modelling the mass distributions of strong gravitational lenses is often necessary to use them as astrophysical and cosmological probes. With the high number of lens systems ($>10^5$) expected from upcoming surveys, it is timely to explore…

Astrophysics of Galaxies · Physics 2021-02-24 S. Schuldt , S. H. Suyu , T. Meinhardt , L. Leal-Taixé , R. Cañameras , S. Taubenberger , A. Halkola

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

The region of the second ionization of helium in the Sun is a narrow layer near the surface. Ionization induces a local change of the adiabatic exponent $\Gamma_1$, which produces a characteristic signature in the frequencies of p-modes. By…

Astrophysics · Physics 2007-05-23 M. J. P. F. G. Monteiro , M. J. Thompson

Rotational line strengths, computed from eigenvectors of Hund's case (a) matrix representations of the upper and lower Hamiltonians using Wigner-Witmer basis functions, show a larger than expected influence from the well known perturbation…

Atomic Physics · Physics 2017-01-31 James O. Hornkohl , Christian G. Parigger

The Hinode mission has revealed copious amounts of horizontal flux covering the quiet Sun. Local dynamo action has been proposed to explain the presence of this flux. We sought to test whether the quiet Sun flux detected by Hinode is due to…

Solar and Stellar Astrophysics · Physics 2013-07-03 D. Buehler , A. Lagg , S. K. Solanki

We report on spectropolarimetric observations of a near-IR line of Mn I located at 15262.702 A whose intensity and polarization profiles are very sensitive to the presence of hyperfine structure. A theoretical investigation of the magnetic…

We carried out the Stokes diagnostics of new two-dimensional magnetohydrodynamic models with a continuous evolution of magnetogranulation in the course of two hours of the hydrodynamic (solar) time. Our results agree satisfactorily with the…

Solar and Stellar Astrophysics · Physics 2012-10-25 V. A. Sheminova

Obtaining observational constraints on the role of turbulent effects for the solar dynamo is a difficult, yet crucial, task. Without such knowledge, the full picture of the operation mechanism of the solar dynamo cannot be formed. The…

Solar and Stellar Astrophysics · Physics 2021-10-04 A. P. Prabhu , N. K. Singh , M. J. Käpylä , A. Lagg

We present a comparative study of the intensity contrast in synthetic CH-band and violet CN-band filtergrams computed from a high-resolution simulation of solar magnetoconvection. The underlying simulation has an average vertical magnetic…

Astrophysics · Physics 2009-11-13 Han Uitenbroek , Alexandra Tritschler

Polarization that is produced by coherent scattering can be modified by magnetic fields via the Hanle effect. According to standard theory the Hanle effect should only be operating in the Doppler core of spectral lines but not in the wings.…

Solar and Stellar Astrophysics · Physics 2011-02-11 M. Sampoorna , J. O. Stenflo , K. N. Nagendra , M. Bianda , R. Ramelli , L. S. Anusha

The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. We re-analyse available spectropolarimetric material by…

Solar and Stellar Astrophysics · Physics 2015-06-11 S. Hubrig , J. F. Gonzalez , I. Ilyin , H. Korhonen , M. Schoeller , I. Savanov , R. Arlt , F. Castelli , G. Lo Curto , M. Briquet , T. H. Dall

Standard statistical analysis of the magnetic properties of the quiet Sun rely on simple histograms of quantities inferred from maximum-likelihood estimations. Because of the inherent degeneracies, either intrinsic or induced by the noise,…

Solar and Stellar Astrophysics · Physics 2014-12-03 A. Asensio Ramos , M. J. Martínez González

Magnetic field vector measurements are always ambiguous, that is, two or more field vectors are solutions of the observed polarisation. The aim of the present paper is to solve the ambiguity by comparing the ambiguous field vectors obtained…

Solar and Stellar Astrophysics · Physics 2019-09-18 T. Kalewicz , V. Bommier

Regular remote sensing of the magnetic field embedded within the million-degree solar corona is severely lacking. This reality impedes fundamental investigations of the nature of coronal heating, the generation of solar and stellar winds,…

Submillimeter dust polarization measurements of a sample of 50 star-forming regions, observed with the SMA and the CSO covering pc-scale clouds to mpc-scale cores, are analyzed in order to quantify the magnetic field importance. The…