Results 61 to 70 of about 10,729 (219)
Evolution of Open Magnetic Flux During Substorms: The Effects of Dipole Tilt Angle
Geophysical Research Letters, Volume 53, Issue 6, 28 March 2026.Abstract There is a long‐standing debate on the causes of the semiannual variation of geomagnetic activity. One of the prevailing hypotheses is that the Earth's dipole tilt angle Ψ ${\Psi }$ modulates the dayside reconnection rate, causing the so‐called equinoctial effect. Here we perform the first large‐scale statistical study to test this hypothesis.
A. Nair +3 more
wiley +1 more source
Unipolarity of the Solar Magnetic Field in Equatorial Coronal Holes
The Astrophysical JournalA study of the unbalanced magnetic polarity distribution of 70 coronal holes was performed. Data from the Helioseismic and Magnetic Imager were used to examine the photospheric line-of-sight magnetic field ( B _LOS ) beneath these coronal holes.
Khagendra Katuwal, R. T. James McAteer
doaj +1 more source
Fully Kinetic Simulations of Ion‐Acoustic Waves in Asymmetric Reconnection With Cold Ions
Geophysical Research Letters, Volume 53, Issue 5, 16 March 2026.Abstract In collisionless plasma, ion‐acoustic wave (IAW) is an important candidate for enhancing resistivity and viscosity, yet their presence and role in magnetic reconnection remain poorly understood. Here, we employ 2.5‐D particle‐in‐cell simulations to investigate IAWs in asymmetric magnetopause reconnection involving a cold ion population ...
Liangjin Song +9 more
wiley +1 more source
Discrete changes in solar coronal hole boundaries
The Astrophysical Journal, 1990 Sequences of Skylab X-ray images near central meridian passages of a large solar coronal hole are used here to examine hole boundary changes with a time resolution of 90 min. It is found that X-ray bright points play a key role in both the expansion and contraction of the coronal hole.
S. W. Kahler, D. Moses
openaire +1 more source
Periodic Density Structures Observed in Ulysses Data: First Results
Journal 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
Global Effect of New Active Regions on Coronal Holes and Their Wind Streams
The Astrophysical JournalSolar wind prediction algorithms and simulations of coronal events often employ photospheric field maps that are assembled over a 27 day solar rotation. This has stimulated efforts to update and better synchronize the maps by applying flux transport and ...
Y.-M. Wang +3 more
doaj +1 more source
Solar coronal-hole plasma densities and temperatures [PDF]
Astronomy & Astrophysics, 2006 Polar plumes extending from the Sun into the solar corona have long been seen during eclipses, and can now be studied without this restriction with telescopes and spectrometers on board of spacecraft. Despite the large amount of observational data available on this prominent phenomenon, it is not clear whether plumes contribute substantially to the ...
openaire +2 more sources
On the Freeze‐In Distance of Solar Wind Fluid Entropy Variability in the Corona
Journal of Geophysical Research: Space Physics, Volume 131, Issue 3, March 2026.Abstract The strong correlation between solar wind entropy and the frozen‐in ion charge state ratio O7+/O6+ ${\mathrm{O}}^{7+}/{\mathrm{O}}^{6+}$ indicates that entropy variability on timescales of hours or longer is preserved from its solar source. This prompts the question: where in the solar atmosphere does this entropy variability come from, and at
Aidan J. Nakhleh +3 more
wiley +1 more source
Soft X-ray telescope (SXRT) [PDF]
The soft X-ray telescope (SXRT) will provide direct images of the solar corona with spatial resolution of about 1 arcsecond. These images will show the global structure of the corona, the location and area of coronal holes, and the presence of even the ...
Moore, R.
core +4 more sources
Solar polar coronal hole - A mathematical simulation
The Astrophysical Journal, 1977 The northern polar region of the sun was studied during July 1973 by Munro and Jackson through use of the white-light coronagraph and the X-ray photographs produced by the Skylab mission. They described the northern polar hole as nearly axisymmetric and gave the geometry and density distribution under this approximation.
S. T. Suess +3 more
openaire +1 more source