Results 71 to 80 of about 5,669 (225)

Chromospheric Heating from Local Magnetic Growth and Ambipolar Diffusion under Nonequilibrium Conditions

The Astrophysical Journal Letters, 2023
The heating of the chromosphere in internetwork regions remains one of the foremost open questions in solar physics. In the present study, we tackle this old problem by using a very-high-spatial-resolution simulation of quiet-Sun conditions performed ...
Juan Martínez-Sykora, Jaime de la Cruz Rodríguez, Milan Gošić, Alberto Sainz Dalda, Viggo H. Hansteen, Bart De Pontieu   +5 more
doaj   +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, Nicholeen Viall, Larry Kepko, Simone Di Matteo   +3 more
wiley   +1 more source

Probing oscillations in the lower solar atmosphere with the FRANCIS integral field unit

Frontiers in Astronomy and Space Sciences
The photosphere is dominated by 3 mHz oscillations, and as we move upward through the solar atmosphere, the dominant frequency is progressively filtered up to 5 mHz, which is commonly observed ubiquitously in the chromosphere. However, the interaction of
S. D. T. Grant, M. Berretti, M. Berretti, G. Chambers, D. B. Jess, D. B. Jess, M. Stangalini, S. Jafarzadeh, H. N. Smitha, F. Berrilli   +9 more
doaj   +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, Nicholeen M. Viall, Susan T. Lepri, Jim M. Raines   +3 more
wiley   +1 more source

Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results [PDF]

, 2015
The chromosphere is a thin layer of the solar atmosphere that bridges the relatively cool photosphere and the intensely heated transition region and corona. Compressible and incompressible waves propagating through the chromosphere can supply significant
Jess, D.B., Jess, D. B.; id_orcid, I. Giagkiozis, S. D. T. Grant, G. Verth, Verth, G., D. B. Jess, Morton, R.J., Fedun, V., Giagkiozis, Ioannis, Morton, Richard, R. J. Morton, Morton, R. J., Jess, David, Giagkiozis, I., Verth, Gary, V. Fedun, Grant, S.D.T., Fedun, Viktor, Grant, Samuel, Grant, S. D. T.; id_orcid   +20 more
core   +1 more source

Formation-height diagnostics across a sunspot: a comparison of Lightweaver radiative transfer and NICOLE inversions using the Ca ii 8542Å line

Frontiers in Astronomy and Space Sciences
The Ca ii 8542Å line is widely used by modern instruments such as SST/CRISP and DKIST to probe the highly structured and dynamic chromosphere. However, interpreting observations in this line requires a characterisation of the effective height ranges ...
Timothy J. Duckenfield, David B. Jess, David B. Jess, Shahin Jafarzadeh, Shahin Jafarzadeh, Luc Rouppe van der Voort, Luc Rouppe van der Voort, Vasco M. J. Henriques, Vasco M. J. Henriques   +8 more
doaj   +1 more source

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

Solar Activity Impacts on Ionospheric Scintillation and Precise Point Positioning Based on Multi‐Year GNSS and Scintillation Observations

Space Weather, Volume 24, Issue 3, March 2026.
Abstract Solar activity induces ionospheric irregularities that degrade Global Navigation Satellite System (GNSS) performance through amplitude and phase scintillation. Although numerous studies have investigated event‐driven or regional responses, the nonlinear coupling between solar radiation, ionospheric scintillation, and precise point positioning (
Jincheng Li, Qi Liu, Xiaomin Luo, Manuel Hernández‐Pajares, Enric Monte‐Moreno, Guangxia Wang, Heng Yang, Chuanding Zhang, Li Yang, Yaoyao Liu   +9 more
wiley   +1 more source

Structure and dynamics of the solar chromosphere [PDF]

, 2002
The thesis "Structure and dynamics of the solar chromosphere" of J.M. Krijger is a study on the behavior of the solar chromosphere, the thin layer just above the solar surface (photosphere) visible in purple red light during a total solar eclipse.
Krijger, Johannes Mattheus
core  

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