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Coronal holes are large-scale structures in the solar atmosphere that feature a reduced temperature and density in comparison to the surrounding quiet Sun and are usually associated with open magnetic fields. We perform a differential…

Solar and Stellar Astrophysics · Physics 2021-03-01 Stephan G. Heinemann , Jonas Saqri , Astrid M. Veronig , Stefan J. Hofmeister , Manuela Temmer

On February 12, 2021 two subsequent eruptions occurred above the West limb, as seen along the Sun-Earth line. The first event was a typical slow Coronal Mass Ejection (CME), followed $\sim 7$ hours later by a smaller and collimated…

Coronal modelling is crucial for a better understanding of solar and helio-physics. Due to the strong brightness of the Sun and the lack of white light observations of the solar atmosphere and low corona (1-1.5R$_\odot$), total solar…

Solar and Stellar Astrophysics · Physics 2026-01-21 Tinatin Baratashvili , Haopeng Wang , Daria Sorokina , Andrea Lani , Stefaan Poedts

We carried out white-light observations of the total solar eclipse on 13 November 2012 at two sites, where the totality occurred 35 minutes apart. We caught an ongoing coronal mass ejection (CME) and a pre-CME loop structure just before the…

Solar and Stellar Astrophysics · Physics 2020-07-29 Yoichiro Hanaoka , Jun Nakazawa , Osamu Ohgoe , Yoshiaki Sakai , Kazuo Shiota

The Sun's corona has interested researchers for multiple reasons, including the search for solution for the famous coronal heating problem and a purely practical consideration of predicting geomagnetic storms on Earth. There exist numerous…

Solar and Stellar Astrophysics · Physics 2019-11-13 Dan Aksim , Alexey Melnikov , Dmitry Pavlov , Sergey Kurdubov

Measurements of the temperature and density structure of the solar corona provide critical constraints on theories of coronal heating. Unfortunately, the complexity of the solar atmosphere, observational uncertainties, and the limitations…

Solar and Stellar Astrophysics · Physics 2009-07-22 Harry P. Warren , David H. Brooks

Comparison of appropriate theoretical derived line ratios with observational data can yield estimates of a plasma's physical parameters, such as electron density or temperature. The usual practice in the calculation of the line ratio is the…

Solar and Stellar Astrophysics · Physics 2014-11-20 J. G. Doyle , S. Chapman , P. Bryans , D. Perez-Suarez , A. Singh , H. Summers , D. W. Savin

On 2019 July 2 a total solar eclipse -- visible across some parts of the Southern Pacific Ocean, Chile and Argentina -- will enable observations of the Sun's large-scale coronal structure. The structure of the Sun's corona and their…

Solar and Stellar Astrophysics · Physics 2021-09-01 Soumyaranjan Dash , Prantika Bhowmik , Athira B S , Nirmalya Ghosh , Dibyendu Nandy

Understanding the density structure of the solar corona is important for modeling both coronal heating and the solar wind. Direct measurements are difficult because of line-of-sight integration and possible unresolved structures. We present…

Solar and Stellar Astrophysics · Physics 2016-09-28 Michael Hahn , Daniel Wolf Savin

The value of the eclipse solar radius during the 2017 August 21 total solar eclipse was estimated to be $S_{\odot} = (959.95\pm 0.05)"$ at $1\,au$ with no significant dependence on wavelength. The measurement was obtained from the analysis…

Solar and Stellar Astrophysics · Physics 2021-09-30 Luca Quaglia , John Irwin , Konstantinos Emmanouilidis , Alessandro Pessi

8000 images of the Solar corona were captured during the June 2001 total Solar eclipse. New software for the alignment of the images and an automated technique for detecting intensity oscillations using multi scale wavelet analysis were…

Astrophysics · Physics 2009-11-10 A. C. Katsiyannis , F. Murtagh

We report on the detection (10 \sigma) of 917 events of long-period (3 to 16 hours) intensity pulsations in the 19.5 nm passband of the SOHO Extreme ultraviolet Imaging Telescope. The data set spans from January 1997 to July 2010, i.e the…

Solar and Stellar Astrophysics · Physics 2014-03-05 F. Auchère , K. Bocchialini , J. Solomon , E. Tison

Differential Emission Measure (DEM) inversion methods use the brightness of a set of emission lines to infer the line-of-sight (LOS) distribution of the electron temperature ($T_e$) in the corona. DEM inversions have been traditionally…

Solar and Stellar Astrophysics · Physics 2023-07-12 Benjamin Boe , Cooper Downs , Shadia Habbal

The quiet solar corona emits meter-wave thermal bremsstrahlung. Coronal radio emission can only propagate above that radius, $R_\omega$, where the local plasma frequency eqals the observing frequency. The radio interferometer LOw Frequency…

Solar and Stellar Astrophysics · Physics 2018-06-13 C. Vocks , G. Mann , F. Breitling , M. M. Bisi , B. Dabrowski , R. Fallows , P. T. Gallagher , A. Krankowski , J. Magdalenic , C. Marque , D. Morosan , H. Rucker

Coronal dimming of extreme ultraviolet (EUV) emission has the potential to be a useful forecaster of coronal mass ejections (CMEs). As emitting material leaves the corona, a temporary void is left behind which can be observed in spectral…

Solar and Stellar Astrophysics · Physics 2014-06-25 J. P. Mason , T. N. Woods , A. Caspi , B. J. Thompson , R. A. Hock

Measuring the global magnetic field of the solar corona remains exceptionally challenging. The fine-scale density structures observed in white light images taken during Total Solar Eclipses (TSEs) are currently the best proxy for inferring…

Solar and Stellar Astrophysics · Physics 2020-06-10 Benjamin Boe , Shadia Habbal , Miloslav Druckmuller

We present narrowband observations of the Fe XIV (530.3 nm), Fe X (637.4 nm), and Fe XI (789.2 nm) coronal emission lines from the 2023 April 20 Total Solar Eclipse in Australia. We deployed pairs of telescopes for each emission line that…

The 8 April 2024 total solar eclipse (TSE) provides a unique opportunity to study the solar corona. This work presents our prediction of the solar corona at the time of the eclipse based on magnetohydrodynamic (MHD) modeling performed with…

Solar flare electron acceleration is an efficient process, but its properties (mechanism, location) are not well constrained. Via hard X-ray (HXR) emission, we routinely observe energetic electrons at the Sun, and sometimes we detect…

Solar and Stellar Astrophysics · Physics 2023-10-09 Ross Pallister , Natasha L. S. Jeffrey

We use The Sun Watcher with Active Pixel System detector and Image Processing (SWAP) imager onboard the Project for Onboard Autonomy 2 (PROBA2) mission to study the evolution of large-scale EUV structures in the solar corona observed…