Results 41 to 50 of about 173,010 (211)

Multi-wavelength Radio Continuum Emission Studies of Dust-free Red Giants [PDF]

, 2013
Multi-wavelength centimeter continuum observations of non-dusty, non-pulsating K spectral-type red giants directly sample their chromospheres and wind acceleration zones.
Brown, Alexander, Drake, Stephen, Harper, Graham M., O'Gorman, Eamon, Richards, Anita M. S.   +4 more
core   +3 more sources

Deriving the Coronal Separatrix‐Web With the WSA Model

Journal of Geophysical Research: Space Physics, Volume 130, Issue 8, August 2025.
Abstract We demonstrate a new capability of the Wang‐Sheeley‐Arge (WSA) model to routinely derive the coronal separatrix web (S‐web) as a standard data product. We describe our methodology for deriving the squashing factor (Q $Q$) and we use Carrington rotation (CR) 2109 to illustrate the validation of our output with that derived from the POT3D model.
Samantha Wallace, Aleida K. Higginson, David G. Simpson, Nicholeen M. Viall, Peter Wyper, C. Nick Arge   +5 more
wiley   +1 more source

Ultraviolet observations of stellar chromospheric activity

The Astrophysical Journal, 1982
A survey is presented of chromospheric and transition region (TR) line emission in late-type stars obtained with the IUE satellite. A wide variation in TR emission (ions formed near T = 100,000 K) at a given position in the H-R diagram is found, contradicting theories that incorporate only acoustic energy generation and deposition.
L. Hartmann, A. K. Dupree, J. C. Raymond
openaire   +1 more source

Solar Wind Heavy Ions and Alpha Particles Within Earth's Magnetosphere and Their Variability With Upstream Conditions

Journal of Geophysical Research: Space Physics, Volume 130, Issue 8, August 2025.
Abstract Working toward the goal of understanding solar wind (SW) entry to the Earth's magnetosphere, this study examines solar‐origin ion composition in the magnetotail. During its trajectory, Wind spent a significant amount of time in the Earth's magnetotail, where its SupraThermal Ion Composition Spectrometer (STICS) measured the mass and mass per ...
S. Colón‐Rodríguez, M. W. Liemohn, J. M. Raines, S. T. Lepri   +3 more
wiley   +1 more source

Magnetic Activity of TESS Objects Observed in the LAMOST Medium-resolution Spectral Survey

The Astrophysical Journal Supplement Series
A combination of spectroscopic and photometric observations provides an excellent data sample for studying stellar chromospheric activity. We have combined LAMOST medium-resolution spectra with TESS 2 minute light curves and extracted over 530,000 ...
Tianhao Su, Li-yun Zhang, Prabhakar Misra, Xianming L. Han, Yinpeng Wang, Wenjie Li, Zhongzhong Zhu, Qingfeng Pi, Hongpeng Lu   +8 more
doaj   +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

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

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

Stellar model chromospheres. XIII - M dwarf stars

The Astrophysical Journal, 1982
Single-component, homogeneous model chromospheres that are consistent with high-resolution profiles of the Ca II K line calibrated in surface flux units for three dMe and 2 dM stars observed at quiescent times are constructed. The models reveal several systematic trends.
M. S. Giampapa, S. P. Worden, J. L. Linsky   +2 more
openaire   +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