Results 51 to 60 of about 860 (219)

Magnetized supersonic downflows in the chromosphere. A statistical study using the He I 10830 \r{A} lines

, 2022
The chromosphere above active regions (ARs) on the Sun hosts magnetized supersonic downflows. Studies of these supersonic downflows help to decipher the magnetic fine structure and dynamics of the chromosphere.
A. Lagg, S. K. Solanki, Solanki, S. K., Solanki, S., Sowmya, K., Durán, J. S. Castellanos, K. Sowmya, Castellanos Durán, J., Lagg, A., J. S. Castellanos Durán, Castellanos Durán, J. S., Korpi-Lagg, A.   +11 more
core   +1 more source

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, Katja Poppenhäger, Ekaterina Ilin   +2 more
wiley   +1 more source

Determining the Magnetic Field of Active Region Plages Using the Whole CLASP2/2.1 Spectral Window

The Astrophysical Journal
The Chromospheric LAyer SpectroPolarimeter missions, CLASP2 and CLASP2.1, demonstrated that the near-UV spectral region between 279.30 and 280.68 nm is suitable for studying the magnetism of the solar chromosphere.
David Afonso Delgado, Tanausú del Pino Alemán, Javier Trujillo Bueno, Ryohko Ishikawa, Ernest Alsina Ballester, David E. McKenzie, Luca Belluzzi, Christian Bethge, Ken Kobayashi, Takenori J. Okamoto, Laurel A. Rachmeler, Donguk Song, Jiří Štěpán, Bart de Pontieu, Adam R. Kobelski, Genevieve D. Vigil, Frédéric Auchère, Ryouhei Kano, Amy Winebarger   +18 more
doaj   +1 more source

A Statistical Study of IRIS Observational Signatures of Nanoflares and Nonthermal Particles

The Astrophysical Journal, 2023
Nanoflares are regarded as one of the major mechanisms of magnetic energy release and coronal heating in the solar outer atmosphere. We conduct a statistical study on the response of the chromosphere and transition region to nanoflares, as observed by ...
Kyuhyoun Cho, Paola Testa, Bart De Pontieu, Vanessa Polito   +3 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

Near-ultraviolet Spectropolarimetry as a Tracer of Magnetic Markers of Flux Rope Formation

The Astrophysical Journal
We investigate the suitability of the combined spectral windows of Mg ii h and k and the Fe ii lines around 261 nm as magnetic markers of filament formation.
David Afonso Delgado, Rebecca Centeno, Roberto Casini, Matthias Rempel   +3 more
doaj   +1 more source

Expulsion of Counter Evershed Flows from Sunspot Penumbrae

The Astrophysical Journal, 2023
In addition to the Evershed flow directed from the umbra toward the outer boundary of a sunspot, under special circumstances a counter Evershed flow (CEF) in the opposite direction also occurs.
J. S. Castellanos Durán, A. Korpi-Lagg, S. K. Solanki   +2 more
doaj   +1 more source

Photospheric and chromospheric activity on the young solar-type star HD 171488 (V889 Herculis) [PDF]

Astronomy and Astrophysics, 2010
Aims. We present the results of contemporaneous spectroscopic and photometric monitoring of the young solar-type star HD 171488 (Prot 1.337 days) aimed at studying surface inhomogeneities at both photospheric and chromospheric levels. Methods. Echelle FOCES spectra (R 40000) and Johnson BV photometry have been performed in August 2006, with a good ...
Frasca, A., Biazzo, K., Kovari, Zs, Marilli, E., Cakirli, O.   +4 more
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, Nicholeen M. Viall, Susan T. Lepri, Jim M. Raines   +3 more
wiley   +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