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Numerical models of the solar wind and coronal mass ejections (CMEs) utilize photospheric magnetic field observations to prescribe the inner boundary conditions for the plasma solutions. These magnetic field data are available to the…

Solar and Stellar Astrophysics · Physics 2026-02-03 Nishtha Sachdeva , Zhenguang Huang , Gabor Toth , Hongfan Chen , Ward B. Manchester , Bart van der Holst

Coronal holes are regions on the Sun's surface that map the foot-prints of open magnetic field lines. We have developed an automated routine to detect and track boundaries of long-lived coronal holes using full-disk EUV images obtained by…

Solar and Stellar Astrophysics · Physics 2015-02-24 Chris Lowder , Jiong Qiu , Robert Leamon , Yang Liu

State-of-the-art coronagraphs employed on extreme adaptive optics enabled instruments, are constantly improving the contrast detection limit for companions at ever closer separations to the host star. In order to constrain their properties…

Instrumentation and Methods for Astrophysics · Physics 2015-11-11 Nemanja Jovanovic , Olivier Guyon , Frantz Martinache , Prashant Pathak , Janis Hagelberg , Tomoyuki Kudo

We propose a coronagraphic system with fourth-order null for off-axis segmented telescopes, which is sufficiently insensitive to the telescope pointing errors and finite angular diameter of the host star to enable high-contrast imaging of…

Instrumentation and Methods for Astrophysics · Physics 2020-05-06 Satoshi Itoh , Taro Matsuo

The solar corona and young solar wind may be characterized by critical surfaces -- the sonic, Alfv\'en, and first plasma-$\beta$ unity surfaces -- that demarcate regions where the solar wind flow undergoes certain crucial transformations.…

Solar and Stellar Astrophysics · Physics 2019-03-20 Rohit Chhiber , Arcadi V. Usmanov , William H. Matthaeus , Melvyn L. Goldstein

Linear polarized light has been used to view the solar corona for over 150 years. While the familiar Stokes representation for polarimetry is complete, it is best matched to a laboratory setting and therefore is not the most convenient…

Instrumentation and Methods for Astrophysics · Physics 2022-03-14 Craig E. DeForest , Daniel B. Seaton , Matthew J. West

Through its magnetic activity, the Sun governs the conditions in Earth's vicinity, creating space weather events, which have drastic effects on our space- and ground-based technology. One of the most important solar magnetic features…

Solar and Stellar Astrophysics · Physics 2022-05-18 Fadil Inceoglu , Yuri Y. Shprits , Stephan G. Heinemann , Stefano Bianco

Telescopes such as the Atmospheric Imaging Assembly aboard the Solar Dynamics Observatory, a NASA satellite, collect massive streams of high resolution images of the Sun through multiple wavelength filters. Reconstructing pixel-by-pixel…

Instrumentation and Methods for Astrophysics · Physics 2015-12-15 Nathan M Stein , David A van Dyk , Vinay L Kashyap

Knowledge about the background solar wind plays a crucial role in the framework of space weather forecasting. In-situ measurements of the background solar wind are only available for a few points in the heliosphere where spacecraft are…

Solar and Stellar Astrophysics · Physics 2013-12-05 C. Gressl , A. M. Veronig , M. Temmer , D. Odstrcil , J. A. Linker , Z. Mikic , P. Riley

Inferring magnetic and thermodynamic information from spectropolarimetric observations relies on the assumption of a parameterized model atmosphere whose parameters are tuned by comparison with observations. Often, the choice of the…

Solar and Stellar Astrophysics · Physics 2015-06-03 A. Asensio Ramos , R. Manso Sainz , M. J. Martinez Gonzalez , B. Viticchie , D. Orozco Suarez , H. Socas-Navarro

On 21 August 2017 a total solar eclipse swept across the contiguous United States providing excellent opportunities for diagnostics of the Sun's corona. The Sun's coronal structure is notoriously difficult to observe except during solar…

Solar and Stellar Astrophysics · Physics 2017-10-03 Dibyendu Nandy , Prantika Bhowmik , Anthony R. Yeates , Suman Panda , Rajashik Tarafder , Soumyaranjan Dash

Fewer than 1% of all exoplanets detected to date have been characterized on the basis of spectroscopic observations of their atmosphere. Unlike indirect methods, high-contrast imaging offers access to atmospheric signatures by separating…

Instrumentation and Methods for Astrophysics · Physics 2020-04-08 Axel Potier , Pierre Baudoz , Raphaël Galicher , Garima Singh , Anthony Boccaletti

Previous work utilising NASA's High-resolution Coronal Imager (Hi-C 2.1) 17.2 nm observations revealed that, even at the increased spatial scales available in the data-set, there may be evidence for coronal structures that are still not…

Solar and Stellar Astrophysics · Physics 2020-10-21 Thomas Williams , Robert W. Walsh , Hardi Peter , Amy R. Winebarger

Coronal Holes (CHs) are regions of open magnetic field lines, resulting in high speed solar wind. Accurate detection of CHs is vital for space weather prediction. This paper presents an intramethod ensemble for coronal hole detection based…

Solar and Stellar Astrophysics · Physics 2024-11-08 Jeremy A. Grajeda , Laura E. Boucheron , Michael S. Kirk , Andrew Leisner , C. Nick Arge

The efficacy of coronal mass ejection (CME) observations as a key input to space weather forecasting is explored by comparing on and off Sun-Earth line observations from the ESA/NASA SOHO and NASA STEREO spacecraft. A comparison is made of…

Solar and Stellar Astrophysics · Physics 2023-05-10 Richard A. Harrison , Jackie A. Davies , David Barnes , Christian Möstl

One-dimensional, semi-empirical models of the solar atmosphere are widely employed in numerous contexts within solar physics, ranging from the determination of element abundances and atomic parameters to studies of the solar irradiance and…

Solar and Stellar Astrophysics · Physics 2024-04-11 J. M. Borrero , I. Milic , A. Pastor Yabar , A. J. Kaithakkal , J. de la Cruz Rodriguez

Focusing on the well motivated aperture mass statistics $\Map$, we study the possibility of constraining cosmological parameters using future space based SNAP class weak lensing missions. Using completely analytical results we construct the…

Astrophysics · Physics 2007-05-23 Dipak Munshi , Patrick Valageas

We report a detailed analysis of the coronal abundance of 4 stars with varying levels of activity and with accurately known photospheric abundances. The coronal abundance is determined here using a line flux analysis and a full…

Astrophysics · Physics 2009-11-10 J. Sanz-Forcada , F. Favata , G. Micela

The objective of this study is to develop a fully compressible magnetohydrodynamic solver for fast simulations of the global dynamo of the Sun using unstructured grids and GPUs. Accurate modeling of the Sun's convective layers is vital to…

Solar and Stellar Astrophysics · Physics 2025-02-26 Aidan Paoli , Chunlei Liang

Solar eruptive phenomena, like flares and coronal mass ejections(CMEs) are governed by magnetic fields. To describe the structure of these phenomena one needs information on the magnetic flux density and the electric current density vector…

Solar and Stellar Astrophysics · Physics 2015-06-17 Tilaye Tadesse , T. Wiegelmann , Pevtsov A Alexei , P. Macneice , S. Gosain