Results 1 to 10 of about 164 (131)

Far-ultraviolet Emission Line Investigation of Flares on AU Mic

The Astrophysical Journal
The role of nonthermal proton energy transportation during solar and stellar flares is largely unknown; a better understanding of this physical process will allow us to rectify longstanding deficiencies in flare models.
Adalyn Gibson, Adam F. Kowalski, Adina D. Feinstein   +2 more
doaj   +1 more source

Slow Solar Wind: Origin in an Independent Small‐Scale Solar Dynamo

Geophysical Research Letters, Volume 52, Issue 13, 16 July 2025.
Abstract Separation of the solar wind (SW) into three flow types (coronal mass ejections (CMEs), high speed streams (HSSs), and slow solar wind (SSW)) reveals an inverse relationship between the percentage of time Earth spends in SSW during a year and its annually averaged magnetic field strength (B).
E. W. Cliver, I. G. Richardson, S. F. Martin   +2 more
wiley   +1 more source

Double-edged Sword: The Influence of Tidal Interaction on Stellar Activity in Binaries

The Astrophysical Journal
Using the LAMOST DR7 low-resolution spectra, we carried out a systematic study of stellar chromospheric activity in both single and binary stars. We constructed a binary sample and a single-star sample, mainly using the binary belt and the main sequence ...
Yuedan Ding, Shidi Zhang, Henggeng Han, Wenyuan Cui, Song Wang, Min Fang, Yawei Gao   +6 more
doaj   +1 more source

Robust Statistical Techniques for Operational Maintenance of the 10.7 cm Solar Radio Flux

Space Weather, Volume 23, Issue 5, May 2025.
Abstract The F10.7 solar radio flux is a critical quantity for operational space weather nowcasting and forecasting, where it is routinely used as a driver for coupled atmospheric models to estimate a variety of important quantities such as the neutral atmospheric density.
Daniel A. Brandt, Erick F. Vega, Brian J. Thelen   +2 more
wiley   +1 more source

Quasi‐Periodic Pulsations in Ionospheric TEC Synchronized With Solar Flare EUV Emission

Journal of Geophysical Research: Space Physics, Volume 130, Issue 4, April 2025.
Abstract The extreme ultraviolet (EUV) and X‐ray radiation emitted during solar flares has been shown to significantly increase the electron density of the Earth's ionosphere. During flares, quasi‐periodic pulsations in X‐ray flux originating in the corona have previously been linked to subsequent pulsations in the Earth's ionospheric D‐region. Similar
Aisling N. O’Hare, Susanna Bekker, Laura A. Hayes, Ryan O. Milligan   +3 more
wiley   +1 more source

The Stagger Code for Accurate and Efficient, Radiation-coupled Magnetohydrodynamic Simulations

The Astrophysical Journal
We describe the Stagger code for simulations of magnetohydrodynamic (MHD) systems. This is a modular code with a variety of physics modules that will let the user run simulations of deep stellar atmospheres, sunspot formation, stellar chromospheres and ...
Robert F. Stein, Åke Nordlund, Remo Collet, Regner Trampedach   +3 more
doaj   +1 more source

Multi‐Source Forecast of Solar Cycle Flare Activity Using the Novel Informer‐Based Models

Space Weather, Volume 23, Issue 4, April 2025.
Abstract Solar flares, the significant indicators of solar activity, have an impact on Earth's satellites and communication systems. Accurate prediction of solar flare events is crucial for mitigating these effects. In this work, we use multiple data sources, including Geostationary Operational Environmental Satellites soft X‐ray flare flux and the ...
Jie Cao, Tingting Xu, Linhua Deng, Miao Wan, Xinhua Zhao, Yang Peng, Xueliang Zhou, Wenhua Wang, Lidong Huang, Wencheng Wang, Lei Yang, Weihong Zhou   +11 more
wiley   +1 more source

Stellar Coronae And Chromospheres In The Era Of Asteroseismology

, 2018
Stellar magnetic activity is an important parameter to study as it can give insights into stellar activity cycles and even how the stellar dynamo operates. However, as cool stars evolve along the main sequence, they lose angular momentum due to magnetic braking.
Booth, R. S., Poppenhaeger, K., Watson, C. A., Silva Aguirre, V., Stello, D., Wolk, S. J.   +5 more
openaire   +2 more sources

Stellar Chromospheric Activity Database of Solar-like Stars Based on the LAMOST Low-resolution Spectroscopic Survey. III. Calibrating the Chromospheric Basal Flux and the Connection to Stellar Rotation

The Astrophysical Journal Supplement Series
Based on the Ca ii H and K lines observed by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, we employ the photospheric ( ${R}_{{\rm{HK}}}^{{\prime} }$ ) and basal ( ${R}_{{\rm{HK}},L}^{+}$ ) flux-calibrated chromospheric activity indices ...
Weitao Zhang, Han He, Jun Zhang
doaj   +1 more source

Investigating the Temperature Sensitivity of UV Line Ratios in the 280 nm Region of Solar-like Stars

The Astrophysical Journal
Stellar UV spectra are fundamental diagnostics of physical and magnetic properties of stars. For instance, lines like Mg ii at 280 nm serve as valuable indicators of stellar activity, providing insights into the activity levels of Sun-like stars and ...
Valentina Penza, Serena Criscuoli, Raffaele Reda, Luca Bertello, Giuseppe Bono, Dario Del Moro, Valentina D’Orazi, Luca Giovannelli, Giuseppina Nigro, Francesco Berrilli   +9 more
doaj   +1 more source