Results 61 to 70 of about 1,834 (171)

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

Hubble Space Telescope Constraints on the Winds and Astrospheres of Red Giant Stars [PDF]

, 2016
We report on an ultraviolet spectroscopic survey of red giants observed by the Hubble Space Telescope, focusing on spectra of the Mg II h & k lines near 2800 A in order to study stellar chromospheric emission, winds, and astrospheric absorption. We focus
Harper, Graham M., Müller, Hans-Reinhard, Wood, Brian E.   +2 more
core   +3 more sources

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

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

Stellar chromospheres [PDF]

Developments in the understanding and use of chromospheric diagnostics are discussed with emphasis on the following aspects: (1) trends emerging from semiempirical models of single stars; (2) the validity of claims that theoretical models of ...
Linsky, J. L.
core   +1 more source

Ca II H and K Chromospheric Emission Lines in Late K and M Dwarfs

, 2006
We have measured the profiles of the Ca II H and K chromospheric emission lines in 147 main sequence stars of spectral type M5-K7 (0.30-0.55 solar masses) using multiple high resolution spectra obtained during six years with the HIRES spectrometer on the
Doyle J. G., Emily Rauscher, Geoffrey W. Marcy, Mathioudakis M., Panagi P. M., Reid N., Rutten R. G. M., Schrijver C. J.   +7 more
core   +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

First Global Machine Learning Model to Predict the Rate of TEC Index (ROTI) Response to X‐Class Solar Flares

Space Weather, Volume 23, Issue 3, March 2025.
Abstract Solar flares are bursts of electromagnetic radiation originating in the Sun's atmosphere. Solar flares cause a rapid increase in ionization in the ionosphere, resulting in radio signal interference. This paper aims to predict the ionospheric response to the solar flare of various characteristics in all latitudes around the dayside ionosphere ...
A. Mahmoudian, F. Ghorbali, M. Vazifehkhah Hafteh   +2 more
wiley   +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

First Observations of a Geomagnetic Superstorm With a Sub‐L1 Monitor

Space Weather, Volume 23, Issue 3, March 2025.
Abstract Forecasting the geomagnetic effects of solar coronal mass ejections (CMEs) is currently an unsolved problem. CMEs, responsible for the largest values of the north‐south component of the interplanetary magnetic field, are the key driver of intense and extreme geomagnetic activity.
E. Weiler, C. Möstl, E. E. Davies, A. M. Veronig, U. V. Amerstorfer, T. Amerstorfer, J. Le Louëdec, M. Bauer, N. Lugaz, V. Haberle, H. T. Rüdisser, S. Majumdar, M. Reiss   +12 more
wiley   +1 more source