Results 81 to 90 of about 15,079 (225)

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

Horizontal supergranule-scale motions inferred from TRACE ultraviolet observations of the chromosphere

, 2010
We study horizontal supergranule-scale motions revealed by TRACE observation of the chromospheric emission, and investigate the coupling between the chromosphere and the underlying photosphere.
Aiouaz, Aiouaz, Attie, Axford, Berrilli, Cadavid, Carlsson, Chae, Curdt, Dammasch, Damé, Damé, de Wijn, de Wijn, Deubner, Dowdy, E. Marsch, Foukal, Gabriel, Giovanelli, Goode, Goode, H. E. Potts, H. Tian, Handy, He, He, Hoekzema, Hoekzema, Hoekzema, Innes, J.-S. He, Jin, Kamio, Krijger, Krijger, Leighton, Lin, Lites, Livingston, Loukitcheva, Marsch, Marsch, Martin, McAteer, McIntosh, Nindos, November, November, November, November, Peter, Potts, Potts, Potts, R. Attie, Rast, Remling, Rieutord, Rimmele, Roudier, Rutten, Rutten, Rutten, Rutten, Shimojo, Simon, Simon, Sivaraman, Sivaraman, Skartlien, Solanki, Strous, Tian, Tian, Tian, Tian, Title, Tritschler, Tu, Vernazza, Wang, Wang, Wang, Wang, Wedemeyer, Worden, Yang, Yang, Yi, Zhang, Zhang, Zhang   +92 more
core   +1 more source

Height dependence of the penumbral fine-scale structure in the inner solar atmosphere [PDF]

, 2018
We studied the physical parameters of the penumbra in a large and fully-developed sunspot, one of the largest over the last two solar cycles, by using full-Stokes measurements taken at the photospheric Fe I 617.3 nm and chromospheric Ca II 854.2 nm lines
Ermolli, I., Giorgi, F., Guglielmino, S. L., Jafarzadeh, S., Murabito, Mariarita, Romano, P., Socas-Navarro, H., Stangalini, M., Zuccarello, F.   +8 more
core   +2 more sources

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

The Potential of the Wavelength-integrated Scattering Polarization of the Hydrogen Lyα Line for Probing the Solar Chromosphere

The Astrophysical Journal, 2023
The intensity and the linear scattering polarization profiles of the hydrogen Ly α line encode valuable information on the thermodynamic and magnetic structure of the upper layers of the solar chromosphere.
E. Alsina Ballester, L. Belluzzi, J. Trujillo Bueno   +2 more
doaj   +1 more source

X-ray emission from dense plasma in CTTSs: Hydrodynamic modeling of the accretion shock

, 2008
High spectral resolution X-ray observations of CTTSs demonstrate the presence of plasma at T~2-3X10^6 K and n_e~10^11-10^13 cm^-3, unobserved in non-accreting stars.
A. Maggio, Anders, Argiroffi, Betta, Brown, C. Argiroffi, Calvet, Chevalier, Cowie, F. Reale, Feigelson, Field, Fryxell, G. G. Sacco, G. Peres, Günther, Günther, Johns-Krull, Kashyap, Kastner, Koldoba, Lamzin, Langer, MacNeice, Peres, Preibisch, Robrade, Romanova, S. Orlando, Schmitt, Smith, Telleschi, Vernazza   +32 more
core   +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

Formation of the Transition Region for the Quiet Sun

The Astrophysical Journal Letters, 2023
We propose a partially ionized collisional two-fluid model of the formation of the transition region between the cool dense chromosphere and hot tenuous corona for the quiet Sun.
Paul Song, Jiannan Tu, David B. Wexler
doaj   +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

Heating of solar chromosphere by electromagnetic wave absorption in a plasma slab model

, 2011
The heating of solar chromospheric inter-network regions by means of the absorption of electromagnetic (EM) waves that originate from the photospheric blackbody radiation is studied in the framework of a plasma slab model.
Aschwanden M. J., D. Tsiklauri, Heald M. A., Huba J. D., Mihalas D., R. Pechhacker   +5 more
core   +1 more source