Results 1 to 10 of about 1,834 (171)

Measuring the magnetic fields in the chromospheres of low-mass stars [PDF]

Nature Communications
Magnetic fields in the upper atmospheres of solar-like stars are believed to provide an enormous amount of energy to power the hot coronae and drive large-scale eruptions that could impact the habitability of planetary systems around these stars. However,
Tianqi Cang, Pascal Petit, Jean-François Donati, Hui Tian, Jianning Fu, Hao Li, Stefano Bellotti, Xueying Hu, Xiaoyu Ma, Arturo Lopez Ariste, Keyu Xing, Julien Morin, Hongpeng Lu, Weikai Zong   +13 more
doaj   +3 more sources

The Influence of Stellar Chromospheres and Coronae on Exoplanet Transmission Spectroscopy

Astrophysical Journal Letters
A main source of bias in transmission spectroscopy of exoplanet atmospheres is magnetic activity of the host star in the form of stellar spots, faculae, or flares. However, the fact that main-sequence stars have a chromosphere and a corona and that these
Aviv Ofir, Oded Aharonson
exaly   +2 more sources

Stellar Parameters and Spectroscopic Properties of TESS Objects Observed in the LAMOST Low- and Medium-resolution Spectral Survey

The Astrophysical Journal Supplement Series, 2022
Stellar parameters and magnetic activity are important for the understanding of stellar physics and dynamo theory. We have used LAMOST spectroscopic surveys to study stellar parameters and magnetic activity properties of TESS objects.
Li-yun Zhang, Tianhao Su, Prabhakar Misra, Xianming L. Han, Gang Meng, Qingfeng Pi, Jiawei Yang   +6 more
doaj   +1 more source

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

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

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

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

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

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

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