Results 21 to 30 of about 173,010 (211)

Stellar Convection Zones, Chromospheres, and Rotation

The Astrophysical Journal, 1966
O. C. Wilson
openalex   +2 more sources

Modeling Stellar Ca ii H and K Emission Variations: Spot Contribution to the S-index

The Astrophysical Journal Letters, 2023
The S -index is a measure of emission in the Ca ii H and K lines and is a widely used proxy of stellar magnetic activity. It has been assumed until now that the S -index is mainly affected by bright plage regions in the chromosphere.
K. Sowmya, A. I. Shapiro, L. H. M. Rouppe van der Voort, N. A. Krivova, S. K. Solanki   +4 more
doaj   +1 more source

Accretion-powered chromospheres in classical T Tauri stars [PDF]

, 2011
(Abridged) Optical spectra of classical T Tauri stars (cTTS) are rich in emission lines of low-excitation species that are composed of narrow and broad components, related to two regions with different kinematics, densities, and temperatures.
Aiad, Al-Naimi, Alencar, Appenzeller, Ardila, Argiroffi, Artemenko, Basri, Batalha, Berdyugina, Beristain, Beristain, Bertout, Bertout, Bertout, Bertout, Bouvier, Bouvier, Brickhouse, Calvet, Chavarria-K., Cram, Cram, Dall, Donati, Donati, Donati, Donati, Edwards, Edwards, F. M. Walter, Fang, Fischer, G. F. Gahm, Gahm, Gameiro, Grankin, Guenther, Gullbring, Gullbring, Güdel, H. C. Stempels, Hartigan, Hartigan, Hessman, Hussain, Johns, Johns-Krull, Kenyon, Krautter, Kravtsova, Kupka, Kwan, Lamzin, Lamzin, Long, Lorenzetti, Mohanty, Mundt, Muzerolle, Muzerolle, Orlando, P. P. Petrov, Percy, Petrov, Petrov, Petrov, Richter, Romanova, Romanova, Romanova, S. A. Artemenko, Smith, Smith, Stempels, Stempels, Valenti, Van Den Ancker   +77 more
core   +1 more source

Living with a Red Dwarf: X-Ray, UV, and Ca ii Activity–Age Relationships of M Dwarfs

The Astrophysical Journal, 2023
The vast majority of stars in the nearby stellar neighborhood are M dwarfs. Their low masses and luminosities result in slow rates of nuclear evolution and minimal changes to the stars’ observable properties, even along astronomical timescales.
Scott G. Engle
doaj   +1 more source

Addendum - Detection of Mass Loss in Stellar Chromospheres

The Astrophysical Journal, 1980
R. E. Stencel, D. J. Mullan
openaire   +2 more sources

HST Low-resolution Stellar Library

The Astrophysical Journal Supplement Series, 2023
In order to provide fundamental stellar spectra that extend into the UV, Hubble Space Telescope’s Space Telescope Imaging Spectrograph targeted 556 stars via proposals GO9088, GO9786, GO10222, and GO13776.
Tathagata Pal, Islam Khan, Guy Worthey, Michael D. Gregg, David R. Silva   +4 more
doaj   +1 more source

Is Core Angular Momentum Key to the Giant Dynamo?

Universe, 2022
The pros and cons of core angular momentum dissipation into the convective envelopes of giants as a driver of giant activity is discussed in face of the observational evidence, which points to two ”magnetic strips“, in the HRD, where in the first, at the
Klaus-Peter Schröder, Renada Konstantinova-Antova   +1 more
doaj   +1 more source

BOSS Ultracool Dwarfs I: Colors and Magnetic Activity of M and L dwarfs [PDF]

, 2014
We present the colors and activity of ultracool (M7-L8) dwarfs from the Tenth Data Release of the Sloan Digital Sky Survey (SDSS). We combine previous samples of SDSS M and L dwarfs with new data obtained from the Baryon Oscillation Sky Survey (BOSS) to ...
Bochanski, John J., Davenport, James R. A., Ge, Jian, Hawley, Suzanne L., Schmidt, Sarah J., Schneider, Donald P., West, Andrew A.   +6 more
core   +3 more sources

Modeling the Chromosphere and Transition Region of Planet-hosting Star GJ 436

The Astrophysical Journal, 2023
Ahead of upcoming space missions intending to conduct observations of low-mass stars in the ultraviolet (UV) spectral region it becomes imperative to simultaneously conduct atmospheric modeling from the UV to the visible (VIS) and near-infrared (NIR ...
Dominik Hintz, Sarah Peacock, Travis Barman, Birgit Fuhrmeister, Evangelos Nagel, Andreas Schweitzer, Sandra V. Jeffers, Ignasi Ribas, Ansgar Reiners, Andreas Quirrenbach, Pedro J. Amado, Victor J. S. Béjar, José A. Caballero, Artie P. Hatzes, David Montes   +14 more
doaj   +1 more source

New and Improved Lyα Reconstructions for M and K Dwarfs

The Astrophysical Journal, 2023
The Ly α emission line is the brightest UV emission line in M and K dwarf spectra and serves as an important tool for studies of stellar chromospheres, the interstellar medium, and exoplanet atmospheres.
Angeli Sandoval, Allison Youngblood, R. O. Parke Loyd, Kevin France   +3 more
doaj   +1 more source