Results 41 to 50 of about 151,165 (141)

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

Evidence for extended chromospheres surrounding red giant stars [PDF]

, 1982
Observational evidence and theoretical arguments are summarized which indicate that regions of partially ionized hydrogen extending several stellar radii are an important feature of red giant and supergiant stars.
Stencel, R. E.
core  

Prospects for ALMA Studies of the Solar-Stellar Connecon

, 2016
ALMA provides a splendid opportunity to observe a wide range of star types at millimeter wavelengths to investigate the solar-stellar connection. I will compare the sensitivities and wavelength coverages of ALMA and the JVLA to highlight the discovery ...
Linsky, Jeffrey, Linsky, Jeffrey (5266309)   +1 more
core   +1 more source

The California-Kepler Survey. XI. A Survey of Chromospheric Activity through the Lens of Precise Stellar Properties

The Astrophysical Journal
Surveys of exoplanet host stars are valuable tools for assessing population level trends in exoplanets, and their outputs can include stellar ages, activity, and rotation periods.
Howard Isaacson, Stephen R. Kane, Brad Carter, Andrew W. Howard, Lauren Weiss, Erik A. Petigura, Benjamin Fulton   +6 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

The Near-infrared Ca ii Triplet as a Stellar Activity Indicator: A Library and Comparative Study

The Astrophysical Journal Supplement Series
We have established and released a new stellar index library of the Ca ii triplet, which serves as an indicator for characterizing the chromospheric activity of stars.
Xin Huang, Yuji He, Zhongrui Bai, Hailong Yuan, Mingkuan Yang, Ming Zhou, Yiqiao Dong, Mengxin Wang, Han He, Jinghua Zhang, Yaoquan Chu, Yongheng Zhao, Yong Zhang, Haotong Zhang   +13 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

Stellar population gradients in galaxy discs from the CALIFA survey : the influence of bars [PDF]

, 2014
We acknowledge financial support from the research projects under grants AYA2010-21887-C04-03, AYA2010-21322-C03-03 and AYA2010-15081 by the Spanish Ministerio de Ciencia e Innovación.While studies of gas-phase metallicity gradients in disc galaxies are ...
Wisotzki, L., S. Zibetti, Márquez, I., D. Mast, Papaderos, P., R. García Benito, Rosales-Ortega, F.F., Sánchez, S. F., I. Pérez, Sánchez, S.F., J. Falcón-Barroso, Ruiz Lara, T., P. Sánchez-Blázquez, R. Cid Fernandes, L. Wisotzki, G. van de Ven, de Lorenzo Cáceres, A., P. Papaderos, C. Catalán-Torrecilla, M. Mollá, González Delgado, R., Mendoza, M. A., Aguerri, J.A.L., F. F. Rosales-Ortega, Mendez Abreu, Jairo, Ruiz-Lara, T., Cid Fernandes, R., A. de Lorenzo-Caceres, J. Méndez-Abreu, Zibetti, S., T. Ruiz-Lara, Mendoza, M.A., Iglesias Paramo, Jorge, B. Husemann, Sánchez Blázquez, Patricia, Falcón Barroso, J., Bland-Hawthorn, J., M. A. Mendoza, B. Jungwiert, Catalán Torrecilla, Cristina, Mollá, M., A. Galazzi, C. J. Walcher, A. Gil de Paz, Rosales Ortega, F. F., Mast, D., Marino, Raffaella Anna, Husemann, B., De Amorim, A., J. A. L. Aguerri, Aguerri, J. A. L., Gil De Paz, Armando, Marino, R.A., J. Bland-Hawthorn, A. de Amorim, Pérez, I., R. A. Marino, Walcher, C. J., Méndez Abreu, J., I. Márquez, Walcher, C.J., Galazzi, A., Iglesias-Páramo, J., Jungwiert, B., S. F. Sánchez, R. González Delgado, De Lorenzo-Caceres Rodriguez, Adriana, Catalán-Torrecilla, C., Gil De Paz, A., Van De Ven, G., Falcón-Barroso, J., García Benito, R., Sánchez-Blázquez, P., Jorge Iglesias-Páramo   +73 more
core   +1 more source

Nature of HD 251108: An RS CVn Binary with a Long-term Evolving Spot

The Astrophysical Journal
Recently, the Lobster Eye Imager for Astronomy detected the longest-lasting and most energetic stellar X-ray flare event from HD 251108. In this work, we redetermined the atmospheric parameters of HD 251108 using three spectroscopic observations obtained
Xinlin Zhao, Song Wang, B. Fuhrmeister, J. H. M. M. Schmitt, Xuan Mao, He-Yang Liu, Xiaohong Yang, Jifeng Liu   +7 more
doaj   +1 more source

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