Results 31 to 40 of about 525 (133)
Searching for Rotational X‐Ray Modulation on TIC 277539431
Astronomische 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
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
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
Journal of Geophysical Research: Space Physics, Volume 131, Issue 2, February 2026.Abstract Solar superflares of S‐class (>X10 in soft X‐rays) pose extreme space weather hazards, yet their prediction remains a fundamental challenge owing to their rapid and transient natures and the limitations of conventional event‐based forecasts. We introduce for the first time, a probabilistic spatiotemporal framework designed to identify extended
V. M. Velasco Herrera +12 more
wiley +1 more source
Space Weather, Volume 24, Issue 2, February 2026.Abstract A demonstrated failure mode for operational solar flare forecasting is the inability to forecast flares that occur near, or just beyond, the solar limb. To address this shortcoming, we develop a “4π $4{\uppi }$” full‐heliosphere event forecasting framework and evaluate its statistical classification ability against this specific challenge.
K. D. Leka +5 more
wiley +1 more source
Mapping the Sun's upper photosphere with artificial neural networks
, 2021 We have developed an inversion procedure designed for high-resolution solar spectro-polarimeters, such as Hinode/SP or DKIST/ViSP. The procedure is based on artificial neural networks trained with profiles generated from random atmospheric stratifications for a high generalization capability. When applied to Hinode data we find a hot fine-scale network
Socas-Navarro, Hector +1 more
openaire +2 more sources
Photospheric Magnetic Field of the Sun: Two Patterns of the Longitudinal Distribution
Solar Physics, 2007 14 pages, 5 figures, 1 table; submitted to Solar Physics; 2 figures ...
Vernova, E. S. +2 more
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FLOWS OF MAGNETIC FIELD IN THE SUN’S PHOTOSPHERE
Proceedings of the 25th All-Russia Conference on Solar and Solar-Terrestrial Physics, 2021 E.S. Vernova, M.I. Tyasto, D.G. Baranov
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Тhе telescope for observation of the photosphere of the Sun [PDF]
Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, 2015 V. Efimenko, S. Kaminsky
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Statistical equilibrium and photospheric abundance of silicon in the Sun and in Vega [PDF]
Astronomy & Astrophysics, 2001 Based on detailed non-LTE calculations, an updated determination of the abundance of silicon in the Sun and Vega is presented. The model atom includes neutral and singly ionized stages of silicon with 115 energy levels and 84 line transitions. Non-LTE eects are found to be quite small in the Sun.
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