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We present an analysis of deep $\textit{JWST}$/NIRSpec spectra of star-forming galaxies at $z\simeq1.4-10$, observed as part of the AURORA survey. We infer median low-ionization electron densities of $268_{-49}^{+45}~\rm cm^{-3}$,…

Condensations in the more than 10^6 K hot corona of the Sun are commonly observed in the extreme ultraviolet (EUV). While their contribution to the total solar EUV radiation is still a matter of debate, these condensations certainly provide…

Solar and Stellar Astrophysics · Physics 2012-09-06 H. Peter , S. Bingert , S. Kamio

The Airborne Infrared Spectrometer (AIR-Spec) offers an unprecedented opportunity to explore the Near Infra-Red (NIR) wavelength range. It has been flown at two total solar eclipses, in 2017 and 2019. The wavelength range of the much…

Solar and Stellar Astrophysics · Physics 2023-03-01 G. Del Zanna , J. Samra , A. Monaghan , C. Madsen , P. Bryans , E. DeLuca , H. Mason , B. Berkey , A. de Wijn , Y. Rivera

Coronal density, temperature and heat flux distributions for the equatorial and polar corona have been deduced by Lemaire [2012] from Saito's model of averaged coronal white light (WL) brightness and polarization observations. They are…

Solar and Stellar Astrophysics · Physics 2015-06-05 V. Pierrard , K. Borremans , J. F. Lemaire

To explain the high temperature of the corona, much attention has been paid to the distribution of energy in dissipation events. Indeed, if the event energy distribution is steep enough, the smallest, unobservable events could be the…

Solar and Stellar Astrophysics · Physics 2016-07-06 Vincent Joulin , Éric Buchlin , Jacques Solomon , Chloé Guennou

Aims: We investigate the electron acceleration in convective electric fields of cascading magnetic reconnection in a flaring solar corona and show the resulting hard X-ray (HXR) radiation spectra caused by Bremsstrahlung for the coronal…

Solar and Stellar Astrophysics · Physics 2015-12-09 X. Zhou , J. Büchner , M. Barta , W. Gan , S. Liu

A major open issue concerning the active Sun is the effectiveness with which magnetic reconnection accelerates electrons in flares. A paper published by {\em{Nature}} in 2022 used microwave observations to conclude that the Sun is an almost…

Solar and Stellar Astrophysics · Physics 2025-02-10 Anna Volpara , Paolo Massa , Michele Piana , Anna Maria Massone , A Gordon Emslie

The effect of the electron density stratification on the intensity profiles of the H I Ly-$\alpha$ line and the O VI and Mg X doublets formed in solar coronal holes is investigated. We employ an analytical 2-D model of the large scale…

Astrophysics · Physics 2007-05-23 N. -E. Raouafi , S. K. Solanki

Solar rotational tomography (SRT) applied to white-light coronal images observed at multiple aspect angles has been the preferred approach for determining the three-dimensional (3D) electron density structure of the solar corona. However,…

Solar and Stellar Astrophysics · Physics 2016-10-04 Didier Vibert , Christelle Peillon , Philippe Lamy , Richard A. Frazin , Julien Wojak

It is generally accepted that densities of quiet sun and active region plasma are sufficiently low to justify the optically thin approximation, and it is commonly used in the analysis of line emissions from plasma in the solar corona.…

Solar and Stellar Astrophysics · Physics 2018-02-14 Edward Thiemann , Phillip Chamberlin , Francis Eparvier , Luke Epp

A detailed study is presented of the decaying solar active region NOAA 10103 observed with the Coronal Diagnostic Spectrometer (CDS), the Michelson Doppler Imager (MDI) and the Extreme-ultraviolet Imaging Telescope (EIT) onboard the Solar…

Astrophysics · Physics 2007-05-23 R. O. Milligan , P. T. Gallagher , M. Mathioudakis , F. P. Keenan , D. S. Bloomfield

We present a Differential Emission Measure (DEM) analysis of the quiet solar corona on disk using data obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on {\it Hinode}. We show that the expected quiet Sun DEM distribution can…

Solar and Stellar Astrophysics · Physics 2009-11-09 David H. Brooks , Harry P. Warren , David R. Williams , Tetsuya Watanabe

We present a new correlation method for deriving the F-corona intensity distribution, which is based on the analysis of the evolution of the total and polarized visible light (VL) images. We studied the one-month variation profiles of the…

Solar and Stellar Astrophysics · Physics 2022-03-14 A. Burtovoi , G. Naletto , S. Dolei , D. Spadaro , M. Romoli , F. Landini , Y. De Leo

Using data collected by the Indian Mars Orbiter Mission in October 2021, we investigated coronal regions of the Sun by analyzing the Doppler spectral width of radio signals to estimate solar wind velocity. A simplified equation is…

Solar and Stellar Astrophysics · Physics 2025-04-02 Keshav Aggarwal , R. K. Choudhary , Abhirup Datta , Roopa M. V. , Bijoy K. Dai

The brightness of the emission from coronal loops in the solar atmosphere is strongly dependent on the temperature and density of the confined plasma. After a release of energy, these loops undergo a heating and upflow phase, followed by a…

Solar and Stellar Astrophysics · Physics 2019-03-20 C. D. Johnston , S. J. Bradshaw

Tomography is a powerful technique for recovering the three-dimensional (3D) density structure of the global solar corona. In this work, we present an improved tomography method by introducing radial weighting in the regularization term.…

Solar and Stellar Astrophysics · Physics 2025-03-31 Tongjiang Wang , C. Nick Arge , Shaela I. Jones

The correlation between the plasma density measured in space and the surface potential of an electrically conducting satellite body with biased electric field detectors has been recognized and used to provide density proxies. However, for…

Space Physics · Physics 2022-03-09 Forrest Mozer , Stuart Bale , Paul Kellogg , Davin Larson , Roberto Levi , Orlando Romeo

Stellar coronae have been invoked to explain the apparently extragalactic dispersion measures observed in fast radio bursts. This paper demonstrates that the suggested plasma densities would lead to deviations from the standard dispersion…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-10 Artem V. Tuntsov

Line ratio of $3d-2p$ transition lines in boron-like spectra of Si X, S XII, Ar XIV and Fe XXII has been investigated. Collisional-radiative model calculations reveal that the line ratio is sensitive to the electron density in ranges of…

Astrophysics · Physics 2009-11-13 Guiyun Liang , Gang Zhao

We carried out polarimetric observations of the white-light corona during the total solar eclipses that occurred on 2017 August 21 and 2019 July 2, and successfully obtained data at two different sites for both eclipses. After eliminating…

Solar and Stellar Astrophysics · Physics 2021-11-17 Yoichiro Hanaoka , Yoshiaki Sakai , Koichi Takahashi