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Vector magnetic fields of an active region filament in the photosphere and upper chromosphere are obtained from spectro-polarimetric observations recorded with the Tenerife Infrared Polarimeter (TIP II) at the German Vacuum Tower Telescope…

Solar and Stellar Astrophysics · Physics 2015-06-04 Z. Xu , A. Lagg , S. Solanki , Y. Liu

The solar limb darkening function is well known and is widely employed in models of the solar atmosphere. However, there has been a lack of systematic spectrally resolved measurements. Therefore we recently decided to start an observing…

Solar and Stellar Astrophysics · Physics 2017-08-11 R. Ramelli , M. Setzer , M. Engelhard , M. Bianda , F. Paglia , J. O. Stenflo , G. Küveler , R. Plewe

Observations of the polar region of the Sun are critically important for understanding the solar dynamo and the acceleration of solar wind. We carried out precise magnetic observations on both the North polar region and the quiet Sun at the…

Solar and Stellar Astrophysics · Physics 2015-05-19 Hiroaki Ito , Saku Tsuneta , Daikou Shiota , Munetoshi Tokumaru , Ken'ichi Fujiki

Vertical magnetic fields have been known to exist in the internetwork region for decades, while the properties of horizontal magnetic fields have recently been extensively investigated with \textit{Hinode}. Vertical and horizontal magnetic…

Solar and Stellar Astrophysics · Physics 2015-05-27 Ryohko Ishikawa , Saku Tsuneta

Aims. To study intensity oscillations in the solar chromosphere/corona above a quiet-Sun magnetic network. Methods. We analyse the time series of He II 256.32, Fe XI 188.23 and Fe XII 195.12 spectral lines observed by EUV Imaging…

Astrophysics · Physics 2009-11-13 A. K. Srivastava , D. Kuridze , T. V. Zaqarashvili , B. N. Dwivedi

The chromosphere in internetwork regions of the quiet Sun was regarded as a static and homogeneous layer for a long time. Thanks to advances in observations and numerical modelling, the wave nature of these atmospheric regions received…

Astrophysics · Physics 2015-06-24 Sven Wedemeyer-Böhm

We present results of synthetic spectro-polarimetric diagnostics of radiative MHD simulations of solar surface convection with magnetic fields. Stokes profiles of Zeeman-sensitive lines of neutral iron in the visible and infrared spectral…

Astrophysics · Physics 2009-11-13 S. Shelyag , M. Schuessler , S. K. Solanki , A. Voegler

The continuous high spatial-resolution Doppler observation of the Sun by Solar Dynamics Observatory / Helioseismic and Magnetic Imager allows us to compute helioseismic k-omega power-spectrum diagram using only oscillations inside a…

Solar and Stellar Astrophysics · Physics 2015-06-11 Junwei Zhao , Dean-Yi Chou

Solar filaments are dense and cool plasma clouds in the solar corona. They are supposed to be supported in a dip of coronal magnetic field. However, the models are still under argument between two types of the field configuration; one is…

Solar and Stellar Astrophysics · Physics 2023-05-10 Daiki Yamasaki , Yu Wei Huang , Yuki Hashimoto , Denis P. Cabezas , Tomoko Kawate , Satoru UeNo , Kiyoshi Ichimoto

I present a matched-wave asymptotic analysis of the driving of solar oscillations by a general localised source. The analysis provides a simple mathematical description of the asymmetric peaks in the power spectrum in terms of the relative…

Astrophysics · Physics 2009-10-30 Colin S. Rosenthal

Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed field corona, implying that it originates from the continuous opening and closing of…

Solar and Stellar Astrophysics · Physics 2015-05-27 S. K. Antiochos , Z. Mikić , V. S. Titov , R. Lionello , J. A. Linker

In this work, we study the accuracy that can be achieved when inferring the atmospheric information from realistic numerical magneto-hydrodynamic simulations that reproduce the spatial resolution we will obtain with future observations made…

Our knowledge of the lower solar atmosphere is mainly obtained from spectropolarimetric observations, which are often carried out in the red or infrared spectral range and almost always cover only a single or a few spectral lines. Here we…

Instrumentation and Methods for Astrophysics · Physics 2019-01-30 T. L. Riethmüller , S. K. Solanki

One of the most important features in the solar atmosphere is magnetic network and its rela- tionship with the transition region (TR), and coronal brightness. It is important to understand how energy is transported into the corona and how…

Solar and Stellar Astrophysics · Physics 2018-03-21 Ehsan Tavabi

Angular power spectra and structure functions of the Stokes parameters Q and U and polarized intensity P are derived from three sets of radio polarimetric observations. Two of the observed fields have been studied at multiple frequencies,…

Astrophysics · Physics 2011-05-23 M. Haverkorn , P. Katgert , A. G. de Bruyn

High-resolution observations of the solar photosphere have recently revealed the presence of elongated filamentary bright structures inside sunspot umbrae. These features, which have been called umbral filaments (UFs), differ in morphology,…

Solar and Stellar Astrophysics · Physics 2020-01-24 S. L. Guglielmino , P. Romano , B. Ruiz Cobo , F. Zuccarello , M. Murabito

Small-scale, newly emerging internetwork (IN) magnetic fields are considered a viable source of energy and mass for the solar chromosphere and possibly the corona. Multiple studies show that single events of flux emergence can indeed…

Solar and Stellar Astrophysics · Physics 2025-08-28 Milan Gošić , Bart De Pontieu , Alberto Sainz Dalda

High levels of horizontal magnetic flux have been reported in the quiet-Sun internetwork, often based on Stokes profile inversions. Here we introduce a new method for deducing the inclination of magnetic elements and use it to test magnetic…

Solar and Stellar Astrophysics · Physics 2014-10-01 S. Jafarzadeh , S. K. Solanki , A. Lagg , L. R. Bellot Rubio , M. van Noort , A. Feller , S. Danilovic

We use Hinode/SOT Ca II H-line and blue continuum broadband observations to study the presence and power of high frequency acoustic waves at high spatial resolution. We find that there is no dominant power at small spatial scales; the…

The structure and energy balance of the solar chromosphere remain poorly known. We have used the imaging spectrometer IBIS at the Dunn Solar Telescope to obtain fast-cadence, multi-wavelength profile sampling of Halpha and Ca II 854.2 nm…

Solar and Stellar Astrophysics · Physics 2015-05-13 G. Cauzzi , K. P. Reardon , R. J. Rutten , A. Tritschler , H. Uitenbroek