Results 61 to 70 of about 938 (183)

Propagating and Stationary Bright Knots in the Quiet Sun

The Astrophysical Journal Letters, 2022
The question of what heats the solar chromosphere and corona remains one of the most important puzzles in solar physics and astrophysics. Up to now, two mechanisms are considered to work in heating the chromosphere and corona: magnetic reconnection and ...
Jun Zhang, Yijun Hou, Yue Fang, Feng Chen, Ting Li, Xiaoli Yan, Tao Ding, Zhiping Song, Yongyuan Xiang, Zhong Liu   +9 more
doaj   +1 more source

A New Method for Probabilistic Spatiotemporal Forecasts of Solar Soft X‐Ray “S‐Class” (>X10) Superflares

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, G. Velasco Herrera, W. Soon, A. Özgüç, N. Babynets, A. Tlatov, M. Švanda, S. Qiu, S. Baliunas, B. Kotan, G. González González, L. A. Bautista Flores, M. Pazos   +12 more
wiley   +1 more source

Space Weather Impact of Three Solar Flares Observed by the POEMAS Telescope at 45 and 90 GHz

Journal of Geophysical Research: Space Physics, Volume 130, Issue 11, November 2025.
Abstract Solar flares are often associated with coronal mass ejections (CMEs) that, when directed toward Earth, can disrupt the magnetosphere and impact space weather. In this study, we investigate three long‐duration solar flares observed in 2012 by the POlarization Emission of Millimeter Activity at the Sun (POEMAS) telescopes at 45 and 90 GHz.
Adriana Valio, Karla F. Lopez, José Luis Gamonal Valenzuela, Ruben M. Romero Ramírez, Dougas F. da Silva   +4 more
wiley   +1 more source

Solar Flare Activity, 1937–2024: Introducing the New Hemispheric Solar Flare Index (hSFI) in the Context of 2024's Major Solar Storm Events

Space Weather, Volume 23, Issue 11, November 2025.
Abstract A new daily composite of the solar flare index (SFI) and the hemispherically‐resolved versions (hSFI) are presented for 1937 to 2024. The data set confirms that the northern hemisphere (NH) dominated solar flare activity during Solar Cycles 17 to 21, but that the southern hemisphere has dominated from Solar Cycle 22 to present.
V. M. Velasco Herrera, W. Soon, S. Knoška, A. Özgüç, G. Velasco Herrera, H. Yeşilyaprak, N. Babynets, M. Švanda, J. Muraközy, S. Qiu, D. Riveros‐Rosas, R. Connolly, M. Connolly, A. Tlatov, L. Cappellotto   +14 more
wiley   +1 more source

Solar Radio Wide‐Band Spectroscopy and Imaging Facilities of the Chinese Meridian Project Phase II

Space Weather, Volume 23, Issue 11, November 2025.
Abstract Solar eruptions, including flares and coronal mass ejections, are the most energetic phenomena in the solar system. These explosive events accelerate high‐energy particles and generate electromagnetic radiation from radio to gamma‐ray wavelengths, producing heliospheric disturbances and acting as primary drivers of space weather hazards.
Yihua Yan, Wei Wang, Linjie Chen, Jin Fan, Yao Chen, Shuwang Chang, Fabao Yan, Lihong Geng, Sha Li, Cang Su, Zhijun Chen, Chengming Tan, Bing Wang, Guang Lu, Chuanyang Li, Zhichao Zhou, Fei Liu, Suli Ma, Jun Cheng, Jing Du   +19 more
wiley   +1 more source

Dominant Trends in Jupiter's H3+ ${\mathbf{H}}_{\mathbf{3}}^{\mathbf{+}}$ Northern Aurora: II. Magnetospheric Mapping

Journal of Geophysical Research: Space Physics, Volume 130, Issue 10, October 2025.
Abstract Jupiter's auroral regions have previously been defined by broad‐scale auroral structures, but these are typically obscured by the wide array of temporal variability observed at timescales between minutes and days, making it difficult to understand the underlying magnetospheric biases driving these brightness differences.
Tom S. Stallard, Katie L. Knowles, Henrik Melin, Ruoyan Wang, Emma M. Thomas, Luke Moore, James O’Donoghue, Rosie E. Johnson, Steve Miller, John C. Coxon   +9 more
wiley   +1 more source

Comparison of Solar Imaging Feature Extraction Methods in the Context of Space Weather Prediction With Deep Learning‐Based Models

Journal of Geophysical Research: Machine Learning and Computation, Volume 2, Issue 3, September 2025.
Abstract Recently, many machine learning‐based models have been developed to predict geomagnetic activity several days in advance directly from space‐borne solar imaging. To better understand and improve these models, we compare dimensionality reduction techniques to extract abstract features from solar images for space weather‐related downstream tasks.
Maria Tahtouh, Guillerme Bernoux, Antoine Brunet, Denis Standarovski, Gautier Nguyen, Angélica Sicard   +5 more
wiley   +1 more source

Deriving the Coronal Separatrix‐Web With the WSA Model

Journal of Geophysical Research: Space Physics, Volume 130, Issue 8, August 2025.
Abstract We demonstrate a new capability of the Wang‐Sheeley‐Arge (WSA) model to routinely derive the coronal separatrix web (S‐web) as a standard data product. We describe our methodology for deriving the squashing factor (Q $Q$) and we use Carrington rotation (CR) 2109 to illustrate the validation of our output with that derived from the POT3D model.
Samantha Wallace, Aleida K. Higginson, David G. Simpson, Nicholeen M. Viall, Peter Wyper, C. Nick Arge   +5 more
wiley   +1 more source

Solar Wind Heavy Ions and Alpha Particles Within Earth's Magnetosphere and Their Variability With Upstream Conditions

Journal of Geophysical Research: Space Physics, Volume 130, Issue 8, August 2025.
Abstract Working toward the goal of understanding solar wind (SW) entry to the Earth's magnetosphere, this study examines solar‐origin ion composition in the magnetotail. During its trajectory, Wind spent a significant amount of time in the Earth's magnetotail, where its SupraThermal Ion Composition Spectrometer (STICS) measured the mass and mass per ...
S. Colón‐Rodríguez, M. W. Liemohn, J. M. Raines, S. T. Lepri   +3 more
wiley   +1 more source

Waves in the Chromosphere: Observations [PDF]

, 2003
I review the literature on observational aspects of waves in the solar chromosphere in the first part of this contribution. High-frequency waves are invoked to build elaborate cool-star chromosphere heating theories but have not been detected decisively so far, neither as magnetic modes in network elements nor as acoustic modes in below-the-canopy ...
openaire   +3 more sources