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We analyse the coronal elemental abundances during a small flare using Hinode/EIS observations. Compared to the pre-flare elemental abundances, we observed a strong increase in coronal abundance of Ca XIV 193.84 {\AA}, an emission line with…

We investigate coronal heating and acceleration of the high- and low-speed solar wind in the open field region by dissipation of fast and slow magnetohydrodynamical (MHD) waves through MHD shocks. Linearly polarized \Alfven (fast MHD) waves…

Astrophysics · Physics 2009-11-10 Takeru K. Suzuki

Both remote-sensing measurements using the interplanetary scintillation (IPS) technique and in situ measurements by the Ulysses spacecraft show a bimodal structure for the solar wind at solar minimum conditions. At present what makes the…

Solar and Stellar Astrophysics · Physics 2015-05-27 Bo Li , Li-Dong Xia , Yao Chen

The state of the space environment plays a significant role for forecasting of geomagnetic storms produced by disturbances of the solar wind (SW). Coronal mass ejections (CMEs) passing through the heliosphere often have a prolonged (up to…

Space Physics · Physics 2022-04-27 Vladimir Slemzin , Farid Goryaev , Denis Rodkin

Data obtained from Parker Solar Probe (PSP) since 2021 April have shown the first in situ observation of the solar corona, where the solar wind is formed and accelerated. Here we investigate the alpha-proton differential flow and its…

Solar and Stellar Astrophysics · Physics 2024-01-22 Hao Ran , Ying D. Liu , Chong Chen , Parisa Mostafavi

The coronal magnetic field, despite its overwhelming importance to the physics and dynamics of the corona, has only rarely been measured. Here, the electron density maps derived from images acquired during the total solar eclipse of August…

Solar and Stellar Astrophysics · Physics 2023-03-29 Alessandro Bemporad

A likely candidate mechanism to heat the solar corona and solar wind is low-frequency "Alfv\'enic" turbulence sourced by magnetic fluctuations near the solar surface. Depending on its properties, such turbulence can heat different species…

Solar and Stellar Astrophysics · Physics 2024-09-17 Jonathan Squire , Romain Meyrand , Matthew W. Kunz

We review our state of knowledge of coronal element abundance anomalies in the Sun and stars. We concentrate on the first ionization potential (FIP) effect observed in the solar corona and slow-speed wind, and in the coronae of solar-like…

Solar and Stellar Astrophysics · Physics 2015-09-30 J. Martin Laming

The evolution of a coronal loop is studied by means of numerical simulations of the fully compressible three-dimensional magnetohydrodynamic equations using the HYPERION code. The footpoints of the loop magnetic field are advected by random…

Solar and Stellar Astrophysics · Physics 2016-01-22 R. B. Dahlburg , G. Einaudi , B. D. Taylor , I. Ugarte-Urra , H. P. Warren , A. F. Rappazzo , M. Velli

The ambient solar wind conditions in interplanetary space and in the near-Earth environment are determined by activity on the Sun. Steady solar wind streams modulate the propagation behaviour of interplanetary coronal mass ejections and are…

Modern radio telescopes are extremely sensitive to plasma on the line of sight from a radio source to the antenna. Plasmas in the corona and solar wind produce measurable changes in the radio wave amplitude and phase, and the phase…

Astrophysics · Physics 2009-11-13 Steven R. Spangler , Catherine A. Whiting

Identifying the heating mechanisms of the solar corona and the driving mechanisms of solar wind are key challenges in understanding solar physics. A full three-dimensional compressible magnetohydrodynamic (MHD) simulation was conducted to…

Solar and Stellar Astrophysics · Physics 2020-11-25 Takuma Matsumoto

The dynamics of regions of the solar corona are investigated using Atmospheric Imaging Assembly (AIA) 171\AA\ and 193\AA\ data. The coronal emission from the quiet Sun, coronal loop footprints, coronal moss, and from above a sunspot is…

Solar and Stellar Astrophysics · Physics 2015-06-23 Jack Ireland , R. T. James McAteer , Andrew R. Inglis

During Parker Solar Probe (Parker) Encounter 15 (E15), we observe an 18-hour period of near subsonic ($\mathrm{M_S \sim}$ 1) and sub-Alfv\'enic (SA), $\mathrm{M_A}$ <<< 1, slow speed solar wind from 22 to 15.6 R$_\odot$. As the most extreme…

Recurrent, arc-shaped intensity disturbances were detected by EUV channels in an active region. The fronts were observed to propagate along a coronal loop bundle rooted in a small area within a sunspot umbra. Previous works have linked…

Solar and Stellar Astrophysics · Physics 2022-11-02 M. V. Sieyra , S. Krishna Prasad , G. Stenborg , E. Khomenko , T. Van Doorsselaere , A. Costa , A. Esquivel , J. M. Riedl

In this paper we propose that flux cancellation on small granular scales ($\lesssim 1000$ km) ubiquitously drives reconnection at a multitude of sites in the low solar atmosphere, contributing to chromospheric/coronal heating and the…

Solar and Stellar Astrophysics · Physics 2024-01-23 D. I. Pontin , E. R. Priest , L. P. Chitta , V. S. Titov

Plasma turbulence cascading from MHD to kinetic scales in the heliospheric plasma is believed to play a key role in coronal heating and fast solar wind acceleration, but the properties of the turbulence remain poorly constrained by…

Solar and Stellar Astrophysics · Physics 2026-02-03 Eduard P. Kontar , A. Gordon Emslie , Daniel L. Clarkson , Alexander Pitna

The solar wind is typically categorized as fast and slow based on the measured speed ($v_\mathrm{sw}$). The separation between these two regimes is often set between 400 and 600 km/s without a rigorous definition. Observations of the solar…

Solar and Stellar Astrophysics · Physics 2025-02-19 B. L. Alterman , Y. J. Rivera , S. T. Lepri , R. M. Raines

Solar variability investigations that include magnetic energy coupling are paramount to solving many key solar/stellar physics problems, particularly for understanding the temporal variability of magnetic energy redistribution and heating…

Solar and Stellar Astrophysics · Physics 2016-12-28 N. Brice Orange , David L. Chesny , Bruce Gendre , David C. Morris , Hakeem M. Oluseyi

Although it is widely accepted that photospheric motions provide the energy source and that the magnetic field must play a key role in the process, the detailed mechanisms responsible for heating the Sun's corona and accelerating the solar…

Solar and Stellar Astrophysics · Physics 2016-01-12 Roberto Lionello , Marco Velli , Cooper Downs , Jon A. Linker , Zoran Mikić
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