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Present day solar imaging spectrometers typically yield a few hundred million spectra in one hour of observing time. This number will increase by an order of magnitude for future instruments with larger 4k x 4k sensors as planned to be used…

Solar and Stellar Astrophysics · Physics 2019-06-19 C. Beck , S. Gosain , C. Kiessner

We study the dynamics of plasma along the legs of an arch filament system (AFS) from the chromosphere to the photosphere, observed with high-cadence spectroscopic data from two ground-based solar telescopes: the GREGOR telescope (Tenerife)…

Solar and Stellar Astrophysics · Physics 2020-02-26 S. J. González Manrique , C. Kuckein , A. Pastor Yabar , A. Diercke , M. Collados , P. Gömöry , S. Zhong , Y. Hou , C. Denker

The diagnosis of new high-resolution spectropolarimetric observations of solar prominences made in the visible and near-infrared mainly, requires a radiative modelling taking into account for both multi-dimensional geometry and complex…

Astrophysics · Physics 2015-05-13 L. Leger , F. Paletou

Within the framework of the density matrix theory for the generation and transfer of polarized radiation, velocity density matrix correlations represent an important physical aspect that, however, is often neglected in practical…

Solar and Stellar Astrophysics · Physics 2015-06-15 L. Belluzzi , E. Landi Degl'Innocenti , J. Trujillo Bueno

We constructed a comprehensive model atom for NeI -- NeII using the most up-to-date atomic data available and evaluated the non-local thermodynamic equilibrium (NLTE) line formation for NeI and NeII in classical 1D models representing the…

Solar and Stellar Astrophysics · Physics 2020-06-24 Sofya Alexeeva , Tianxiang Chen , Tatyana Ryabchikova , Weibin Shi , Kozo Sadakane , Masayoshi Nishimura , Gang Zhao

Obtaining the magnetic field vector accurately in the solar atmosphere is essential for studying changes in field topology during flares and to reliably model space weather. We tackle this problem by applying various inversion methods to a…

We tested whether simultaneous spectropolarimetric imaging in two magnetically sensitive optical spectral lines, which probe two different layers of the solar atmosphere (the photosphere and the temperature minimum), can help constrain the…

Aluminium plays a key role in studies of the chemical enrichment of the Galaxy and of globular clusters. However, strong deviations from LTE (non-LTE) are known to significantly affect the inferred abundances in giant and metal-poor stars.…

Solar and Stellar Astrophysics · Physics 2017-11-28 Thomas Nordlander , Karin Lind

The Helioseismic Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) records line-of-sight Dopplergram images of convective flows on the surface. These images are used to obtain the multi-scale convective spectrum. We design…

Solar and Stellar Astrophysics · Physics 2021-08-09 Samarth G Kashyap , Shravan M Hanasoge

Large-scale velocity fields in the solar photosphere remain a mystery in spite of many years of intensive studies. In this thesis, the new method of the measurements of the solar photospheric flow fields is proposed. It is based on local…

Astrophysics · Physics 2007-12-13 Michal Svanda

We present a precise and complete procedure for processing spectral data observed by the 1-meter New Vacuum Solar Telescope (NVST). The procedure is suitable for both the sit-and-stare and raster-scan spectra. In this work, the geometric…

Solar and Stellar Astrophysics · Physics 2017-10-18 Yunfang Cai , Zhi Xu , Zhenggang Li , Yongyuan Xiang , Yuchao Chen , Yu Fu , Kaifan Ji

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

The hydrogen Lyman lines provide important diagnostic information about the dynamics of the chromosphere, but there have been few systematic studies of their variability during flares. We investigate Doppler shifts in these lines in several…

Solar and Stellar Astrophysics · Physics 2016-11-30 Stephen A Brown , Lyndsay Fletcher , Nicolas Labrosse

High-resolution observations of the solar chromosphere at millimeter wavelengths are now possible with the Atacama Large Millimeter Array (ALMA), promising to tackle many open problems in solar physics. Observations from other ground and…

Solar and Stellar Astrophysics · Physics 2018-12-12 João M. da Silva Santos , Jaime de la Cruz Rodríguez , Jorrit Leenaarts

In the first three papers of this series, we investigated the formation of photospheric neutral iron lines in different atmospheres ranging from idealised flux tube models to complex three-dimensional magnetohydrodynamic (3D MHD)…

Solar and Stellar Astrophysics · Physics 2025-05-14 R. Holzreuter , H. N. Smitha , S. K. Solanki

This paper shows the first synthetic tomography of the quiet solar chromosphere formed by spatial maps of scattering polarization. It has been calculated for the CaII 8498, 8542 and 3934 A lines by solving the NLTE (non-local…

Solar and Stellar Astrophysics · Physics 2015-06-23 E. S. Carlin , A Asensio Ramos

A new generation of Ge-based high-resolution gamma-ray spectrometers has allowed accurate measurements to be made of the profiles, widths and energies of the gamma-ray lines emitted in the impulsive phases of solar flares. Here we present…

Astrophysics · Physics 2009-11-11 M. J. Harris , V. Tatischeff , J. Kiener , M. Gros , G. Weidenspointner

We examine the capabilities of a fast and simple method to infer line-of-sight (LOS) velocities from observations of the photospheric Si I 10827 A line. This spectral line is routinely observed together with the chromospheric He I 10830 A…

Solar and Stellar Astrophysics · Physics 2020-01-29 S. J. González Manrique , C. Quintero Noda , C. Kuckein , B. Ruiz Cobo , M. Carlsson

We use 3D radiation magnetohydrodynamic models to investigate how the thermodynamic quantities in the simulation are encoded in observable quantities, thus exploring the diagnostic potential of the 133.5 nm lines. We find that the line core…

Solar and Stellar Astrophysics · Physics 2015-09-30 Bhavna Rathore , Mats Carlsson , Jorrit Leenaarts , Bart De Pontieu

Birmingham Solar Oscillations Network (BiSON) instruments use resonant scattering spectrometers to make unresolved Doppler velocity observations of the Sun. Unresolved measurements are not homogenous across the solar disc and so the…

Solar and Stellar Astrophysics · Physics 2015-05-13 A. M. Broomhall , W. J. Chaplin , Y. Elsworth , R. New