Results 51 to 60 of about 3,072 (224)

Alfvén wave dissipation in the solar chromosphere [PDF]

open access: yesNature Physics, 2018
Magneto-hydrodynamic (MHD) Alfvén waves have been a focus of laboratory plasma physics and astrophysics for over half a century. Their unique nature makes them ideal energy transporters, and while the solar atmosphere provides preferential conditions for their existence, direct detection has proved difficult as a result of their evolving and dynamic ...
Samuel D. T. Grant   +9 more
openaire   +4 more sources

Reconstructing Historical Solar Indices for Predicting Past Space Weather Events

open access: yesSpace Weather, Volume 24, Issue 4, April 2026.
Abstract Modeling and forecasting the near‐Earth space environment, specifically the thermosphere, is particularly important because it affects the motion of low‐Earth orbit objects through atmospheric drag. Solar indices such as F10.7, S10.7, M10.7, and Y10.7 are commonly used as inputs to ionospheric and thermospheric density models.
Poshan Belbase   +4 more
wiley   +1 more source

Solar flux emergence : a three-dimensional numerical study [PDF]

open access: yes, 2008
Flux is continually emerging on the Sun, making its way from the solar interior up into the atmosphere. Emergence occurs on small-scales in the quiet Sun where magnetic fragments emerge, interact and cancel and on large-scales in active regions where ...
Murray, Michelle J.
core  

RADIATING CURRENT SHEETS IN THE SOLAR CHROMOSPHERE [PDF]

open access: yesThe Astrophysical Journal, 2012
An MHD model of a Hydrogen plasma with flow, an energy equation, NLTE ionization and radiative cooling, and an Ohm's law with anisotropic electrical conduction and thermoelectric effects is used to self-consistently generate atmospheric layers over a $50$ km height range.
Goodman, Michael L., Judge, Philip G.
openaire   +2 more sources

Searching for Rotational X‐Ray Modulation on TIC 277539431

open access: yesAstronomische Nachrichten, Volume 347, Issue 3, March 2026.
ABSTRACT TIC 277539431, a fast rotating M7 dwarf, was detected to host the highest latitude flare to date at 81°$$ {81}^{{}^{\circ}} $$. Magnetic activity like stellar flares occurring at high latitude indicate occurrence of coronal loops at these latitudes on fully‐convective M dwarfs. In contrast, sunspots usually occur below 30°$$ {30}^{{}^{\circ}} $
Desmond Dsouza   +2 more
wiley   +1 more source

Observations of small-scale energetic events in the solar transition region: explosive events, UV bursts, and network jets

open access: yesSolar-Terrestrial Physics, 2019
In this paper, we review observational aspects of three common small-scale energetic events in the solar transition region (TR), namely TR explosive events, ultraviolet bursts and jets.
Zhenghua Huang, Bo Li, Lidong Xia
doaj   +1 more source

Extreme Red-wing Enhancements of UV Lines during the 2022 March 30 X1.3 Solar Flare

open access: yesThe Astrophysical Journal, 2023
Here, we present the study of a compact emission source during an X1.3 flare on 2022 March 30. Within a ∼41 s period (17:34:48 UT to 17:35:29 UT), Interface Region Imaging Spectrograph observations show spectral lines of Mg ii , C ii , and Si iv with ...
Yan Xu   +5 more
doaj   +1 more source

Periodic Density Structures Observed in Ulysses Data: First Results

open access: yesJournal of Geophysical Research: Space Physics, Volume 131, Issue 3, March 2026.
Abstract Periodic density structures (PDSs) are advecting quasi‐periodic (periodicities between several minutes and several hours) density enhancements observed in the solar wind and corona. There is strong evidence that PDSs are formed at the Sun.
Brent M. Randol   +3 more
wiley   +1 more source

Solar Chromospheric Heating by Kinetic Alfvén Waves Based on the Three-fluid Model

open access: yesThe Astrophysical Journal
The heating mechanism of the solar chromosphere with a partially ionized plasma has been one of the challenging problems in solar physics. Kinetic Alfvén waves (KAWs) have been applied by many authors to study the heating of the corona and chromosphere ...
Jin-Run Ou   +3 more
doaj   +1 more source

Structure of the solar chromosphere [PDF]

open access: yesProceedings of the International Astronomical Union, 2004
The chromosphere is an intriguing part of the Sun that has stubbornly resisted all attempts at a comprehensive description. Thus, observations carried out in different wavelength bands reveal very different, seemingly incompatible properties. Not surprisingly, a debate is raging between supporters of the classical picture of the chromosphere as a ...
openaire   +2 more sources

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