Results 61 to 70 of about 14,709 (209)

A nanoflare model of quiet Sun EUV emission [PDF]

, 2006
Nanoflares have been proposed as the main source of heating of the solar corona. However, detecting them directly has so far proved elusive, and extrapolating to them from the properties of larger brightenings gives unreliable estimates of the power-law ...
A. Pauluhn, Arzner, Aschwanden, Aschwanden, Audard, Brkovic, Datlowe, Güdel, Harrison, Innes, Krucker, Lin, Lu, Mitra-Kraev, Parker, Parnell, Pauluhn, Rosner, S. K. Solanki, Torrence, Vekstein, Wilhelm, Wilhelm, Winebarger, Withbroe   +24 more
core   +2 more sources

Global Ionospheric TEC Variability: Long‐Term Spectral–Wavelet Analysis and Geomagnetic Storm Event Case Studies

Journal of Geophysical Research: Space Physics, Volume 131, Issue 4, April 2026.
Abstract This study investigates global ionospheric variability using Global Total Electron Content (GTEC), defined as the spatial average of daily averaged Global Ionospheric Maps derived from the International GNSS Service. The analysis spans from 2010 to 2024, covering Solar Cycle 24 and the rising phase of Solar Cycle 25, and incorporates ...
Ramadane Hamed Linjouom Nsangou, Y. Reuveni   +1 more
wiley   +1 more source

The Effect of the Parametric Decay Instability on the Morphology of Coronal Type III Radio Bursts

The Astrophysical Journal Letters, 2023
The nonlinear evolution of Alfvén waves in the solar corona leads to the generation of Alfvénic turbulence. This description of the Alfvén waves involves parametric instabilities where the parent wave decays into slow mode waves giving rise to density ...
Chaitanya Prasad Sishtla, Immanuel Christopher Jebaraj, Jens Pomoell, Norbert Magyar, Marc Pulupa, Emilia Kilpua, Stuart D. Bale   +6 more
doaj   +1 more source

Measurements of Photospheric and Chromospheric Magnetic Fields

, 2015
The Sun is replete with magnetic fields, with sunspots, pores and plage regions being their most prominent representatives on the solar surface. But even far away from these active regions, magnetic fields are ubiquitous.
Centeno, Rebecca, Gosain, Sanjay, Harvey, Jack, Lagg, Andreas, Lites, Bruce   +4 more
core   +1 more source

First NuSTAR Limits on Quiet Sun Hard X-Ray Transient Events [PDF]

, 2017
We present the first results of a search for transient hard X-ray (HXR) emission in the quiet solar corona with the \textit{Nuclear Spectroscopic Telescope Array} (\textit{NuSTAR}) satellite. While \textit{NuSTAR} was designed as an astrophysics mission,
Boggs, Steven E., Caspi, Amir, Christensen, Finn E., Craig, William W., Glesener, Lindsay, Grefenstette, Brian W., Hailey, Charles J., Hannah, Iain G., Harrison, Fiona A., Hudson, Hugh S., Krucker, Säm, Kuhar, Matej, Madsen, Kristin K., Marsh, Andrew J., Smith, David M., Stern, Daniel, White, Stephen M., Wright, Paul J., Zhang, William W.   +18 more
core   +5 more sources

Reconstructing Historical Solar Indices for Predicting Past Space Weather Events

Space 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, Denny M. Oliveira, Theodosios Chatzistergos, Gangkai Poh, Eftyhia Zesta   +4 more
wiley   +1 more source

Relative Elemental Abundances of the Quiet Solar Corona as Determined by SERTS [PDF]

The Astrophysical Journal, 1997
Intensities of extreme-ultraviolet (EUV) spectral lines were measured as a function of radius off the solar limb by two flights (1989 May 5 and 1991 May 7) of the Solar Extreme-ultraviolet Rocket Telescope and Spectrograph (SERTS) for three quiet solar regions. The line-ratio density, line-ratio temperature, and emission measure were determined.
D. A. Falconer, J. M. Davila, R. J. Thomas   +2 more
openaire   +1 more source

A new view of quiet-Sun topology from Hinode/SOT [PDF]

, 2008
Context. With the recent launch of the Hinode satellite our view of the nature and evolution of quiet-Sun regions has been improved. In light of the new high resolution observations, we revisit the study of the quiet Sun's topological nature. Aims.
Haynes, A. L., Parnell, C. E., Regnier, S.   +2 more
core   +3 more sources

Relationship Between Foreshock Structures and Magnetosheath Jets

Journal of Geophysical Research: Space Physics, Volume 131, Issue 4, April 2026.
Abstract Plasma structures with enhanced dynamic pressure know as jets are frequently observed in the magnetosheath. We examine a possible connection of these jets with structures reported in the foreshock like SLAMS or plasmoids. A statistical study of the relation of the upstream conditions and the occurrence rates of magnetosheath (MSH) jets and ...
N. Xirogiannopoulou, O. Goncharov, J. Šafránková, Z. Němeček   +3 more
wiley   +1 more source

Influence of Ionization on the Polytropic Index of the Solar Atmosphere within Local Thermodynamic Equilibrium Approximation

The Astrophysical Journal
An initial theoretical attempt to explain the observed decrease of the polytropic/adiabatic index γ in the solar corona has been accomplished. The chemical reactions of the ionization–recombination processes in local thermodynamic equilibrium (LTE) of a ...
Albert M. Varonov, Todor M. Mishonov
doaj   +1 more source