Results 21 to 30 of about 560 (161)

EDEN Survey: Small Transiting Planet Detection Limits and Constraints on the Occurrence Rates of Planets around Late-M Dwarfs within 15 pc

The Astronomical Journal, 2023
Earth-sized exoplanets that transit nearby, late-spectral-type red dwarfs will be prime targets for atmospheric characterization in the coming decade.
Jeremy Dietrich, Dániel Apai, Martin Schlecker, Kevin K. Hardegree-Ullman, Benjamin V. Rackham, Nicolas Kurtovic, Karan Molaverdikhani, Paul Gabor, Thomas Henning, Wen-Ping Chen, Luigi Mancini, Alex Bixel, Aidan Gibbs, Richard P. Boyle, Samantha Brown-Sevilla, Remo Burn, Timmy N. Delage, Lizxandra Flores-Rivera, Riccardo Franceschi, Gabriele Pichierri, Sofia Savvidou, Jonas Syed, Ivan Bruni, Wing-Huen Ip, Chow-Choong Ngeow, An-Li Tsai, Chia-Lung Lin, Wei-Jie Hou, Hsiang-Yao Hsiao, Chi-Sheng Lin, Hung-Chin Lin, Ritvik Basant, Project EDEN   +32 more
doaj   +1 more source

Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g [PDF]

The Astronomical Journal, 2018
Abstract The atmospheres of late M stars represent a significant challenge in the characterization of any transiting exoplanets because of the presence of strong molecular features in the stellar atmosphere. TRAPPIST-1 is an ultracool dwarf, host to seven transiting planets, and contains its own molecular signatures that can potentially ...
H. R. Wakeford, N. K. Lewis, J. Fowler, G. Bruno, T. J. Wilson, S. E. Moran, J. Valenti, N. E. Batalha, J. Filippazzo, V. Bourrier, S. M. Hörst, S. M. Lederer, J. de Wit   +12 more
openaire   +4 more sources

Infrared Mn i laboratory oscillator strengths for the study of late type stars and ultracool dwarfs [PDF]

Astronomy & Astrophysics, 2010
Aims. The aim of our new laboratory measurements is to measure accurate absolute oscillator strengths for neutral manganese transitions in the infrared needed for the study of late-type stars and ultracool dwarfs. Methods. Branching fractions have been measured by high resolution Fourier transform spectroscopy and combined with radiative level ...
R. Blackwell-Whitehead, Y. V. Pavlenko, G. Nave, J. C. Pickering, H. R. A. Jones, Y. Lyubchik, H. Nilsson   +6 more
openaire   +1 more source

Titanium abundances in late-type stars

Astronomy & Astrophysics, 2022
Context. The titanium abundances of late-type stars are important tracers of Galactic formation history. However, abundances inferred from Ti I and Ti II lines can be in stark disagreement in very metal-poor giants. Departures from local thermodynamic equilibrium (LTE) have a large impact on the minority neutral species and thus influence the ...
Mallinson, J. W. E., Lind, K., Amarsi, Anish, Barklem, Paul, Grumer, Jon, Belyaev, A. K., Youakim, K.   +6 more
openaire   +3 more sources

X‐Ray Spectroscopy of Rapidly Rotating, Late‐Type Dwarf Stars

The Astrophysical Journal, 1999
We present an X-ray spectroscopic analysis of two active dwarf stars with extremely short rotation periods, HD 197890 (Speedy Mic) and Gliese 890, using X-ray data acquired with the ASCA observatory. We analyze the X-ray spectrum of Speedy Mic in two separate time intervals, one corresponding to an apparent stellar flare, the other to "quiescence" or ...
K. P. Singh, S. A. Drake, E. V. Gotthelf, N. E. White   +3 more
openaire   +1 more source

Stellar Atmospheric Parameters for Cool Dwarfs in Gaia Data Release 3

The Astrophysical Journal Supplement Series
We provide a catalog of atmospheric parameters for 1,806,921 cool dwarfs from Gaia Data Release 3 (DR3) that lie within the range covered by LAMOST cool dwarf spectroscopic parameters: 3200 K < T _eff < 4300 K, −0.8 < [M/H] < 0.2 dex, and 4.5 < log g < 5.
Cai-Xia Qu, A-Li Luo, Rui Wang, Hugh R. A. Jones, Bing Du, Xiang-Lei Chen, You-Fen Wang   +6 more
doaj   +1 more source

Mapping the Skies of Ultracool Worlds: Detecting Storms and Spots with Extremely Large Telescopes

The Astrophysical Journal, 2023
Extremely large telescopes (ELTs) present an unparalleled opportunity to study the magnetism, atmospheric dynamics, and chemistry of very-low-mass (VLM) stars, brown dwarfs, and exoplanets.
Michael K. Plummer, Ji Wang
doaj   +1 more source

The EUVE Optical Identification Campaign II: Late-Type and White Dwarf Stars

The Astronomical Journal, 1995
We present optical identifications of nine previously unidentified extreme ultraviolet (EUV) sources discovered during the Extreme Ultraviolet Explorer (EUVE) satellite surveys. The all-sky survey detected four of the sources and the more sensitive deep survey detected the other five sources.
N. Craig, A. Fruscione, J. Dupuis, M. Mathioudakis, J. J. Drake, M. Abbott, C. Christian, R. Green, T. Boroson, S. B. Howell   +9 more
openaire   +1 more source

X-Ray, UV, and Optical Observations of Proxima Centauri’s Stellar Cycle

The Astrophysical Journal
Proxima Cen (GJ 551; dM5.5e) is one of only about a dozen fully convective stars known to have a stellar cycle, and the only one to have long-term X-ray monitoring.
Bradford J. Wargelin, Steven H. Saar, Zackery A. Irving, Jonathan D. Slavin, Peter Ratzlaff, José-Dias do Nascimento Jr   +5 more
doaj   +1 more source

On the Possibility of an Upper Limit on Magnetically Induced Radius Inflation in Low-mass Stars

The Astrophysical Journal
The radii of low-mass stars are observed to be inflated above standard model predictions, especially in magnetically active stars. Typically, the empirical relative radius inflations Δ R / R are ≤10% but in (rare) cases may be ≥20%.
J. MacDonald, D. J. Mullan
doaj   +1 more source