Results 21 to 30 of about 1,868 (166)

The M dwarf problem: Fe and Ti abundances in a volume-limited sample of M dwarf stars [PDF]

Monthly Notices of the Royal Astronomical Society, 2020
ABSTRACT We report iron and titanium abundance measurements from high-resolution spectra in a volume-limited sample of 106 M0 and M0.5 dwarf stars. The sample includes stars north of the celestial equator and closer than 29 parsecs. The results imply that there is an M dwarf problem similar to the previously known G dwarf problem, in ...
Vincent M Woolf, George Wallerstein
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Magnetic Field Measurements of Low-mass Stars from High-resolution Near-infrared IGRINS Spectra

The Astronomical Journal, 2023
We present average magnetic field measurements derived from high-resolution near-infrared IGRINS spectra of a carefully selected sample of 28 M dwarfs. All 28 have reported magnetic field strengths in the literature.
Eunkyu Han, Ricardo López-Valdivia, Gregory N. Mace, Daniel T. Jaffe   +3 more
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Stellar Characterization and Radius Inflation of Hyades M-dwarf Stars from the APOGEE Survey

The Astrophysical Journal, 2023
We present a spectroscopic analysis of a sample of 48 M-dwarf stars (0.2 M _⊙ < M < 0.6 M _⊙ ) from the Hyades open cluster using high-resolution H -band spectra from the Sloan Digital Sky Survey/Apache Point Observatory Galactic Evolution Experiment ...
Fábio Wanderley, Katia Cunha, Diogo Souto, Verne V. Smith, Lyra Cao, Marc Pinsonneault, C. Allende Prieto, Kevin Covey, Thomas Masseron, Ilaria Pascucci, Keivan G. Stassun, Ryan Terrien, Galen J. Bergsten, Dmitry Bizyaev, José G. Fernández-Trincado, Henrik Jönsson, Sten Hasselquist, Jon A. Holtzman, Richard R. Lane, Suvrath Mahadevan, Steven R. Majewski, Dante Minniti, Kaike Pan, Javier Serna, Jennifer Sobeck, Guy S. Stringfellow   +25 more
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Detection of Young Massive White Dwarfs in Core-collapsed Globular Cluster NGC 362

The Astrophysical Journal Letters
Core-collapsed globular clusters are ideal targets to explore the presence of stellar collision products. Here, we have studied 17 far-UV bright white dwarf (WD) members in the globular cluster NGC 362 using data obtained from the Ultra Violet Imaging ...
R. K. S. Yadav, Arvind K. Dattatrey, Annapurni Subramaniam, Geeta Rangwal, Ravi S. Singh   +4 more
doaj   +1 more source

Physical Parameters and Magnetic Activity of M-type Stars Based on the LAMOST DR9, SDSS, and TESS Surveys

The Astrophysical Journal Supplement Series
We analyze a catalog comprising 781,232 spectra from 641,095 M dwarf stars from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) low-resolution spectroscopic data release 9.
Wenjie Li, Li-yun Zhang, Tianhao Su, Xianming L. Han, Prabhakar Misra, Qingfeng Pi   +5 more
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Inhomogeneous structure in the chromospheres of dwarf M stars [PDF]

Monthly Notices of the Royal Astronomical Society, 1991
Linear combinations of observed spectra of the H-alpha and Ca-II resonance and IR lines from the chromospheres of a quiet (Gl 1) and an active (Gl 735) dwarf-M star are compared with the corresponding spectra from a star of intermediate activity (Gl 887).
N. J. Turner, L. E. Cram, R. D. Robinson
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Overestimated Pressure Broadening Misleads Model Spectra in Cool M Dwarf Stars

The Astrophysical Journal Letters
Available one-dimensional stellar models fail to reproduce the observed spectrum of the ultracool M dwarf TRAPPIST-1. In particular, current models predict strong iron hydride (FeH) absorption due to the Wing–Ford bands at 0.99 μ m, yet this spectral ...
Ana Glidden, Veronika Witzke, Alexander I. Shapiro, Sara Seager   +3 more
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The theoretical instability strip of M dwarf stars [PDF]

Monthly Notices of the Royal Astronomical Society, 2013
The overstability of the fundamental radial mode in M dwarf models was theoretically predicted by Rodríguez-López et al. (2012). The periods were found to be in the ranges ~25-40 min and ~4-8 h, depending on stellar age and excitation mechanism. We have extended our initial M dwarf model grid in mass, metallicity, and mixing length parameter.
Rodríguez-López, Cristina, MacDonald, J, Amado, Pedro J., Moya, A., Mullan, D.   +4 more
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Longitudinally Modulated Dynamo Action in Simulated M-dwarf Stars

The Astrophysical Journal, 2022
Abstract M-dwarf stars are well known for the intense magnetic activity that many of them exhibit. In cool stars with near-surface convection zones, this magnetic activity is thought to be driven largely by the interplay of convection and the large-scale differential rotation and circulations it establishes.
Connor P. Bice, Juri Toomre
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Chemical Links between a Young M-type T Tauri Star and Its Substellar Companion: Spectral Analysis and C/O Measurement of DH Tau A

The Astrophysical Journal
The chemical abundance measurements of host stars and their substellar companions provide a powerful tool to trace the formation mechanism of the planetary systems.
Neda Hejazi, Jerry W. Xuan, David R. Coria, Erica Sawczynec, Ian J. M. Crossfield, Paul I. Cristofari, Zhoujian Zhang, Maleah Rhem   +7 more
doaj   +1 more source