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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

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 solar photosphere is filled by a magnetic field which is tangled on scales much smaller than the resolution capability of solar telescopes. This hidden magnetic field can be investigated via the Hanle effect. In 2007 we started a…

Solar and Stellar Astrophysics · Physics 2017-10-02 Renzo Ramelli , Michele Bianda , Svetlana Berdyugina , Luca Belluzzi , Lucia Kleint

Polarized dust emission is a key tracer in the study of interstellar medium and of star formation. The observed polarization, however, is a product of magnetic field structure, dust grain properties and grain alignment efficiency, as well…

A previous study (Paper I) investigated the polarization properties of a variety of simple convex grain shapes, some of which were found to be consistent with the observed polarization properties of interstellar dust from far-ultraviolet to…

Astrophysics of Galaxies · Physics 2025-04-07 B. T. Draine

Solar inter-network magnetic field is the weakest component of solar magnetism, but contributes most of the solar surface magnetic flux. The study on its origin has been constrained by the inadequate tempo-spatial resolution and sensitivity…

Solar and Stellar Astrophysics · Physics 2015-05-26 Chunlan Jin , Jingxiu Wang

Observations of quiet Sun from the Solar Optical Telescope/Spectro-Polarimeter (SOT/SP) aboard the Hinode spacecraft would reveal the magnetic characters of the solar photosphere. By making use of the deep mode observations of three quiet…

Astrophysics · Physics 2008-12-18 Chunlan Jin , Jingxiu Wang , Meng Zhao

An accurate measurement of magnetic field is very important for understanding the formation and evolution of solar magnetic fields. Currently there are two types of solar magnetic field measurement instruments: the filter-based…

Solar and Stellar Astrophysics · Physics 2023-10-10 Mei Zhang , Haocheng Zhang , Chengqing Jiang

It is generally assumed that magnetic fields play an important role in the formation and evolution of protoplanetary disks. One way of observationally constraining magnetic fields is to measure polarized emission and absorption produced by…

Solar and Stellar Astrophysics · Physics 2020-03-04 Stefan Heese , Sebastian Wolf

We describe how the observed polarization properties of an astronomical object are related to its intrinsic polarization properties and the finite temporal and spectral resolutions of the observing device. Moreover, we discuss the effect…

High Energy Astrophysical Phenomena · Physics 2022-01-05 Paz Beniamini , Pawan Kumar , Ramesh Narayan

Spectropolarimetric observations used to infer the solar magnetic fields are obtained with a limited spatial resolution. The effects of this limited resolution on the inference of the open flux over the observed region have not been…

Solar and Stellar Astrophysics · Physics 2024-02-06 Ivan Milic , Rebecca Centeno , Xudong Sun , Matthias Rempel , Jaime de la Cruz Rodriguez

In order to understand the heating of the solar corona it is crucial to obtain empirical information on the magnetic field in its lower boundary (the transition region). To this end, we need to measure and model the linear polarization…

Solar and Stellar Astrophysics · Physics 2015-06-11 Jiri Stepan , Javier Trujillo Bueno , Mats Carlsson , Jorrit Leenaarts

Scattering polarization tends to dominate the linear polarization signals of the Ca II 8542 A line in weakly magnetized areas ($B \lesssim 100$ G), especially when the observing geometry is close to the limb. In this paper we evaluate the…

Solar and Stellar Astrophysics · Physics 2021-09-08 Rebecca Centeno , Jaime de la Cruz Rodriguez , Tanausu del Pino Aleman

We analyse the feasibility of detecting the polarization of the CMB caused by scattering of the remote temperature quadrupole by galaxy clusters with forthcoming CMB polarization surveys. For low-redshift clusters, the signal is strongly…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-24 Alex Hall , Anthony Challinor

Magnetic field measurements in the upper chromosphere and above, where the gas-to-magnetic pressure ratio $\beta$ is lower than unity, are essential for understanding the thermal structure and dynamical activity of the solar atmosphere.…

Solar and Stellar Astrophysics · Physics 2015-06-19 R. Ishikawa , A. Asensio Ramos , L. Belluzzi , R. Manso Sainz , J. Stepan , J. Trujillo Bueno , M. Goto , S. Tsuneta

Spectropolarimetric observations of solar flares in the He I D$_3$ line at 5876 {\AA} are extremely rare, and their diagnostic potential remains largely unexplored. We report the first unambiguous detection of linear polarization in He I…

Probing the magnetism of the upper solar chromosphere requires measuring and modeling the scattering polarization produced by anisotropic radiation pumping in UV spectral lines. Here we apply PORTA (a novel radiative transfer code) to…

Solar and Stellar Astrophysics · Physics 2015-06-23 Jiri Stepan , Javier Trujillo Bueno , Jorrit Leenaarts , Mats Carlsson

Polarization at millimeter wavelengths provides a powerful diagnostic of dust grain properties in protoplanetary disks. Standard models based on solid spherical grains often struggle to reproduce the observed polarization fractions and…

The sizable linear polarization signals produced by the scattering of anisotropic radiation in the core of the Ca I 4227 $\mathrm{\r{A}}$ line constitute an important observable for probing the inhomogeneous and dynamic plasma of the lower…

Solar and Stellar Astrophysics · Physics 2021-03-24 J. Jaume Bestard , J. Trujillo Bueno , J. Štěpán , T. del Pino Alemán

This paper aims to study the polarization of hard X-ray (HXR) sources in the solar atmosphere, including Compton backscattering of photons in the photosphere (the albedo effect) and the spatial distribution of polarization across the…

Solar and Stellar Astrophysics · Physics 2015-05-30 Natasha Jeffrey , Eduard Kontar
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