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We propose and test a wavelet transform modulus maxima method for the au- tomated detection and extraction of coronal loops in extreme ultraviolet images of the solar corona. This method decomposes an image into a number of size scales and…

Solar and Stellar Astrophysics · Physics 2010-02-17 R. T. James McAteer , Pierre Kestener , Alain Arneodo , Andre Khalil

Understanding many physical processes in the solar atmosphere requires determination of the magnetic field in each atmospheric layer. However, direct measurements of the magnetic field in the Sun's corona are difficult to obtain. Using…

Seven different models are applied to the same problem of simulating the Sun's coronal magnetic field during the solar eclipse on 2015 March 20. All of the models are non-potential, allowing for free magnetic energy, but the associated…

Many competing models for the coronal heating and acceleration mechanisms of the high-speed solar wind depend on the solar magnetic field and plasma structure in the corona within heliocentric distances of $5R_\odot$. We report on sensitive…

Solar and Stellar Astrophysics · Physics 2015-06-16 Jason E. Kooi , Patrick D. Fischer , Jacob J. Buffo , Steven R. Spangler

I characterize the global distribution of the 3/4 keV band background with a simple model of the hot Galactic corona, plus an isotropic extragalactic background. The corona is assumed to be approximately polytropic (index = 5/3) and…

Astrophysics · Physics 2009-10-30 Q. Daniel Wang

We benchmark new atomic data against a selection of irradiances obtained from medium-resolution quiet Sun spectra in the EUV, from 60 to 1040 \AA. We use as a baseline the irradiances measured during solar minimum on 2008 April 14 by the…

Solar and Stellar Astrophysics · Physics 2019-04-03 G. Del Zanna

The shape and dynamics of coronal mass ejections (CMEs) vary significantly based on the instrument and wavelength used. This has led to significant debate about the proper definitions of CME/shock fronts, pile-up/compression regions, and…

Solar and Stellar Astrophysics · Physics 2025-08-27 Oleg Stepanyuk , Kamen Kozarev

We present a unified method to derive both solar wind velocities and coronal electron densities in the near-Sun corona using Doppler spectral broadening of spacecraft radio signals. The method is generalized to be frequency independent…

Solar and Stellar Astrophysics · Physics 2026-03-26 Keshav Aggarwal , R. K. Choudhary , Abhirup Datta , Roopa M. V. , Takeshi Imamura , Hiroki Ando

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

A three dimensional (3D) tomographic reconstruction of the local differential emission measure (LDEM) of the global solar corona during the whole heliosphere interval (WHI, Carrington rotation CR-2068) is presented, based on STEREO/EUVI…

Solar and Stellar Astrophysics · Physics 2015-05-20 Alberto M. Vásquez , Zhenguang Huang , Ward B. Manchester , Richard A. Frazin

We estimated the coronal magnetic field strength ($B$) during the 23 July 2016 coronal mass ejection (CME) event using i) the flux rope structure of the CME in the whitelight coronagraph images and ii) the band splitting in the associated…

Solar and Stellar Astrophysics · Physics 2017-11-08 Anshu Kumari , R. Ramesh , C. Kathiravan , T. J. Wang

We present a photometrically accurate restitution of the K and F coronae from white-light images obtained over 24 Years [1996--2019] by the Large-Angle Spectrometric COronagraph "LASCO-C2" onboard the Solar and Heliospheric Observatory…

Solar and Stellar Astrophysics · Physics 2021-03-31 Antoine Llebaria , Philippe Lamy , Hugo Gilardy , Brice Boclet , Jean Loirat

Using a Monte Carlo ray-tracing code in full general relativity, we calculate the transport of photons from a geodesic hot spot emitter through a corona of hot electrons surrounding a black hole. Each photon is followed until it is either…

Astrophysics · Physics 2007-05-23 Jeremy D. Schnittman

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

Context. The solar corona maintains temperatures of a million Kelvin or more. The plasma heating mechanisms responsible for these extreme temperatures are still unclear. Large regions of magnetic activity in the photosphere cause extreme…

Solar and Stellar Astrophysics · Physics 2025-03-17 I. Kraus , Ph. -A. Bourdin , J. Zender , M. Bergmann , A. Hanslmeier

We derived the coronal magnetic field, plasma density, and temperature from the observation of polarization and intensity of radio thermal free-free emission using the Nobeyama Radioheliograph (NoRH) and extreme ultraviolet (EUV)…

We present an investigation of a coronal cavity observed above the western limb in the coronal red line Fe X 6374 {\AA} using a telescope of Peking University and in the green line Fe XIV 5303 {\AA} using a telescope of Yunnan…

We present a study of the differential emission measure (DEM) of a `quiet Sun' area observed in the extreme ultraviolet at normal incidence by the Coronal Diagnostic Spectrometer (CDS) on the SOHO spacecraft. The data used for this work…

Astrophysics · Physics 2009-11-10 A. C. Lanzafame , D. H. Brooks , J. Lang

We report multi-wavelength observations of four solar flares on 2014 July 07. We firstly select these flares according to the soft X-ray (SXR) and extreme ultraviolet (EUV) emissions recorded by the Extreme Ultraviolet Variability…

Solar and Stellar Astrophysics · Physics 2021-05-05 Dong Li , Alexander Warmuth , Lei Lu , Zongjun Ning

Solar five-minute oscillations have been detected in the power spectra of two six-day time intervals from soft X-ray measurements of the Sun observed as a star using the Extreme Ultraviolet Spectrophotometer (ESP) onboard the Solar Dynamics…

Solar and Stellar Astrophysics · Physics 2015-06-12 Leonid Didkovsky , Alexander Kosovichev , Darrell Judge , Seth Wieman , Tom Woods