Results 71 to 80 of about 74,495 (201)

The Evolution of Stellar X-Ray Activity and Angular Momentum as Seen by eROSITA, TESS, and Gaia

The Astrophysical Journal Letters
We have assembled a sample of ∼8200 stars with spectral types F5V–M5V, all having directly measured X-ray luminosities from eROSITA and rotation periods from TESS and having empirically estimated ages via their membership in stellar clusters and groups ...
Keivan G. Stassun, Marina Kounkel
doaj   +1 more source

ON THE GF-VALUES FOR SOME DIATOMIC MOLECULAR SPECTRA

Odessa Astronomical Publications, 2017
In view of rich structure of the energy levels and the variety of transition types which are observable, molecules are the useful tool for investigation of physical parameters of stellar atmospheres, interstellar and circumstellar matter.
L. A. Kuznetsova, A. V. Shavrina
doaj   +1 more source

Deep learning application for stellar parameters determination: I-constraining the hyperparameters

Open Astronomy, 2022
Machine learning is an efficient method for analysing and interpreting the increasing amount of astronomical data that are available. In this study, we show a pedagogical approach that should benefit anyone willing to experiment with deep learning ...
Gebran Marwan, Connick Kathleen, Farhat Hikmat, Paletou Frédéric, Bentley Ian   +4 more
doaj   +1 more source

Kepler planet occurrence rates for mid-type M dwarfs as a function of spectral type [PDF]

, 2019
Previous studies of planet occurrence rates largely relied on photometric stellar characterizations. In this paper, we present planet occurrence rates for mid-type M dwarfs using spectroscopy, parallaxes, and photometry to determine stellar ...
Christiansen, Jessie, Cushing, Michael, Hardegree-Ullman, Kevin, Muirhead, Philip   +3 more
core   +2 more sources

89 New Ultracool Dwarf Comoving Companions Identified with the Backyard Worlds: Planet 9 Citizen Science Project

The Astronomical Journal
We report the identification of 89 new systems containing ultracool dwarf companions to main-sequence stars and white dwarfs, using the citizen science project Backyard Worlds: Planet 9 and cross-reference between Gaia and CatWISE2020.
Austin Rothermich, Jacqueline K. Faherty, Daniella Bardalez-Gagliuffi, Adam C. Schneider, J. Davy Kirkpatrick, Aaron M. Meisner, Adam J. Burgasser, Marc Kuchner, Katelyn Allers, Jonathan Gagné, Dan Caselden, Emily Calamari, Mark Popinchalk, Genaro Suárez, Roman Gerasimov, Christian Aganze, Emma Softich, Chin-Chun Hsu, Preethi Karpoor, Christopher A. Theissen, Jon Rees, Rosario Cecilio-Flores-Elie, Michael C. Cushing, Federico Marocco, Sarah Casewell, Thomas P. Bickle, Les Hamlet, Michaela B. Allen, Paul Beaulieu, Guillaume Colin, Jean Marc Gantier, Leopold Gramaize, Peter Jalowiczor, Martin Kabatnik, Frank Kiwy, David W. Martin, Billy Pendrill, Ben Pumphrey, Arttu Sainio, Jorg Schumann, Nikolaj Stevnbak, Guoyou Sun, Christopher Tanner, Vinod Thakur, Melina Thevenot, Zbigniew Wedracki   +45 more
doaj   +1 more source

GEMINI near-infrared spectroscopic observations of young massive stars embedded in molecular clouds

, 2008
K-band spectra of young stellar candidates in four southern hemisphere clusters have been obtained with the near-infrared spectrograph GNIRS in Gemini South.
A. Rodriguez-Ardila, A. Roman-Lopes, Arias, Balog, Barba, Bik, Bik, Blum, Blum, Blum, Borissova, Bronfman, Calvet, Carr, Casali, Casali, Caswell, Cesaroni, Cesaroni, Churchwell, Dutra, Elias, Figuerêdo, Figuerêdo, Fitzpatrick, Giveon, Glass, Gomes, Grasdalen, Hanson, Hanson, Hanson, Hanson, Hoffmeister, Hofner, Honma, Horner, Indebetouw, Johnson, Koornneef, Kumar, Lada, Lada, Leistra, Liseau, Martins, Massey, Massi, May, Melena, Morisset, Murphy, Nishiyama, Ortiz, R. Ortiz, Rieke, Roman-Lopes, Roman-Lopes, Roman-Lopes, Roman-Lopes, Roman-Lopes, Roman-Lopes, Savage, Sterling, Straw, Straw, Tapia, Walborn, Whitney, Wood, Z. Abraham   +70 more
core   +1 more source

NutMaat: A Python Package for Stellar Spectral Classification on the MK System

The Astronomical Journal
Stellar spectral classification according to the Morgan–Keenan (MK) system remains fundamental to astrophysical studies, yet modern surveys require automated, scalable tools.
R. I. El-Kholy, Z. M. Hayman
doaj   +1 more source

The stellar temperature scale for stars of spectral types from O8 to F6 and the standard deviation of the MK spectral classification

Astrophysics and Space Science, 1991
Empirical effective temperatures of 211 early-type stars found in a previous investigation (Kontizas and Theodossiou, 1980; Theodossiou, 1985) are combined with the effective temperatures of other 313 early-type stars found from literature. From these effective temperatures of a total number of 524 early-type stars of spectral types from O8 to F6 we ...
Theodossiou, E., Danezis, E.
openaire   +2 more sources

Estimating Stellar Atmospheric Parameters and [α/Fe] for LAMOST O-M-type Stars Using a Spectral Emulator

The Astrophysical Journal Supplement Series
Abstract In this paper, we developed a spectral emulator based on the Mapping Nearby Galaxies at Apache Point Observatory Stellar Library (MaStar) and a grouping optimization strategy to estimate effective temperature (T eff), surface gravity (log g), metallicity ([Fe/H]), and the abundance of alpha elements with ...
Jun-Chao Liang, A-Li Luo, Yin-Bi Li, Xiao-Xiao Ma, Shuo Li, Shu-Guo Ma, Hai-Ling Lu, Yun-Jin Zhang, Bing Du, Xiao Kong   +9 more
openaire   +3 more sources

First JWST/NIRSpec Spectroscopy of O Stars in the Small Magellanic Cloud

The Astrophysical Journal Letters
Determining how much mass is removed by stellar winds is crucial to understanding massive star evolution and feedback. However, traditional spectroscopic diagnostics in the UV and optical are not sensitive enough to characterize weak stellar winds of OB ...
Armin Mang Román, Peter Zeidler, Wolf-Rainer Hamann, Lidia M. Oskinova, M. J. Rickard, S. Reyero Serantes, H. Todt, J. S. Gallagher III, D. Massa, D. Pauli, V. Ramachandran, E. Sabbi, A. A. C. Sander   +12 more
doaj   +1 more source