Results 71 to 80 of about 164 (131)

Stellar chromospheric and coronal heating by magnetohydrodynamic waves

The Astrophysical Journal, 1981
An investigation is presented on the way in which the generation of magnetohydrodynamic waves by turbulent motions in stellar convection zones depends on the star's effective temperature, surface gravity, and magnetic field strength. It is shown that the emitted Alfven wave flux (and acoustic slow wave flux in a very strong magnetic field) is in ...
openaire   +1 more source

The Role of Magnetic Fields in Stellar Chromospheres and Transition Regions [PDF]

Symposium - International Astronomical Union, 1983
In this review based largely on observations with the IUE and Einstein satellites, I will summarize the different roles that magnetic fields play in controlling the structure and energy balance in the chromospheres and transition regions of late-type stars.
openaire   +1 more source

A Possible Stellar Coronal Mass Ejection Event Associated with a Long-duration Optical Flare on the RS CVn-type Star UX Arietis

The Astrophysical Journal
Coronal mass ejections (CMEs) are large-scale eruptions of magnetized plasma from stellar coronae, and they are always accompanied by flares. In this study, we present high-resolution spectroscopic observations of a long-duration optical flare on the RS ...
Dongtao Cao, Shenghong Gu
doaj   +1 more source

High Lithium Abundance Connection with the Chromospheric Helium in Red Giants: Spectroscopic and Asteroseismic Analyses

The Astrophysical Journal
We present a study of correlations between high Li abundances and strong chromospheric He i λ 10830 absorption-line strengths in Kepler field giant stars.
Anohita Mallick, Christopher Sneden, Bacham E. Reddy, Melike Afşar   +3 more
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Doppler-shifted Signatures in the Chromospheric Line Profiles of II Pegasi

The Astrophysical Journal
Stellar flares are frequently accompanied by prominence eruptions, coronal mass ejections (CMEs), and other forms of plasma motion. Based on the long-term high-resolution spectroscopic monitoring data set of the RS CVn-type star II Pegasi (II Peg), we ...
Dongtao Cao, Shenghong Gu
doaj   +1 more source

Further Investigation on Chromospheric Activity Patterns of the RS Canum Venaticorum Star V711 Tauri

The Astronomical Journal
We present new long-term spectroscopic observations of the very active RS Canum Venaticorum (RS CVn) star V711 Tauri (V711 Tau), obtained during several observing runs from 2005 to 2021.
Dongtao Cao, Shenghong Gu
doaj   +1 more source

The California Legacy Survey. V. Chromospheric Activity Cycles in Main-sequence Stars

The Astrophysical Journal Supplement Series
We present optical spectroscopy of 710 solar neighborhood stars collected over 20 years to catalog chromospheric activity and search for stellar activity cycles.
Howard Isaacson, Andrew W. Howard, Benjamin Fulton, Erik A. Petigura, Lauren M. Weiss, Stephen R. Kane, Brad Carter, Corey Beard, Steven Giacalone, Judah Van Zandt, Joseph M. Akana Murphy, Fei Dai, Ashley Chontos, Alex S. Polanski, Malena Rice, Jack Lubin, Casey Brinkman, Ryan A. Rubenzahl, Sarah Blunt, Samuel W. Yee, Mason G. MacDougall, Paul A. Dalba, Dakotah Tyler, Aida Behmard, Isabel Angelo, Daria Pidhorodetska, Andrew W. Mayo, Rae Holcomb, Emma V. Turtelboom, Michelle L. Hill, Luke G. Bouma, Jingwen Zhang, Ian J. M. Crossfield, Nicholas Saunders   +33 more
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Magnetic reconnection in partially ionized plasmas. [PDF]

Proc Math Phys Eng Sci, 2020
Ni L, Ji H, Murphy NA, Jara-Almonte J.
europepmc   +1 more source

The Factory and the Beehive. V. Chromospheric and Coronal Activity and Its Dependence on Rotation in Praesepe and the Hyades

The Astrophysical Journal
Low-mass (≲1.2 M _⊙ ) main-sequence stars lose angular momentum over time, leading to a decrease in their magnetic activity. The details of this rotation–activity relation remain poorly understood, however.
Alejandro Núñez, Marcel A. Agüeros, Jason L. Curtis, Kevin R. Covey, Stephanie T. Douglas, Sabine R. Chu, Stanislav DeLaurentiis, Minzhi (Luna) Wang, Jeremy J. Drake   +8 more
doaj   +1 more source

Exploration of the Outer Envelope of the K-giant Star Beta Cet

The Astrophysical Journal
Investigating the atmospheres of giants and supergiants is critical to expanding our knowledge of stellar life cycles, galaxy formation, and the origin of material that forms exoplanets.
Krister E. Nielsen, Gioia Rau, Kenneth G. Carpenter   +2 more
doaj   +1 more source