Results 61 to 70 of about 113,078 (269)
On the lithium abundance of the visual binary components ξ Boo A (G8V) and ξ Boo B (K5V)
Astronomische Nachrichten, Volume 343, Issue 9-10, November-December 2022., 2022 Abstract A spectroscopic investigation of the lithium resonance doublet in ξ Boo A and ξ Boo B in terms of both abundance and isotopic ratio is presented. We obtained new R = 130,000 spectra with a signal‐to‐noise ratio (S/N) per pixel of up to 3200 using the 11.8 m LBT and PEPSI.
Klaus G. Strassmeier, Matthias Steffen
wiley +1 more source
Crossmatching of high-proper motion L, T, and Y brown dwarfs with large photometric surveys
Open Astronomy, 2023 L, T, and Y brown dwarf (BD) exploration is a topical issue. First, the transition boundary between planets and BDs is not fully understood yet. Second, there is a phenomenon called the L/T-transition.
Avdeeva Aleksandra S. +2 more
doaj +1 more source
A Method for Selecting M dwarfs with an Increased Likelihood of Unresolved Ultra-cool Companionship [PDF]
, 2016 Locating ultra-cool companions to M dwarfs is important for constraining low-mass formation models, the measurement of sub-stellar dynamical masses and radii, and for testing ultra-cool evolutionary models. We present an optimised method for identifying M dwarfs which may have unresolved ultra-cool companions.
arxiv +1 more source
Extending the Canada-France Brown Dwarf Survey to the near infrared
EPJ Web of Conferences, 2011 We present the first results of the Canada-France Brown Dwarfs Survey-InfraRed, hereafter CFBDSIR, our near infrared extension to the optical wide field survey CFBDS.
Bertin E. +8 more
doaj +1 more source
The Astrophysical Journal, 2023 Constraining L dwarf properties from their spectra is challenging. Near-infrared (NIR) spectra probe a limited range of pressures, while many species condense within their photospheres. Condensation creates two complexities: gas-phase species “rain out” (
Melanie J. Rowland +2 more
doaj +1 more source
The Y-Type Brown Dwarfs: Estimates of Mass and Age from New Astrometry, Homogenized Photometry and Near-Infrared Spectroscopy [PDF]
, 2017 The survey of the mid-infrared sky by the Wide-field Infrared Survey Explorer (WISE) led to the discovery of extremely cold low-mass brown dwarfs, classified as Y dwarfs, which extend the T class to lower temperatures. Twenty-four Y dwarfs are known at the time of writing.
arxiv +1 more source
The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey [PDF]
, 2010 Context. Thanks to recent and ongoing large scale surveys, hundreds of brown dwarfs have been discovered in the last decade. The Canada-France Brown Dwarf Survey is a wide-field survey for cool brown dwarfs conducted with the MegaCam camera on the Canada-France-Hawaii Telescope telescope. Aims.
arxiv +1 more source
Physical Parameters and Properties of 20 Cold Brown Dwarfs in JWST
The Astrophysical JournalWe present a comprehensive analysis of 20 T and Y dwarfs using spectroscopy from the Near-Infrared Spectrograph (NIRSpec) CLEAR/PRISM and Mid-Infrared Instrument (MIRI) low-resolution spectrometer instruments on the James Webb Space Telescope.
Zhijun Tu, Shu Wang, Jifeng Liu
doaj +1 more source
The Astrophysical Journal, 2023 Brown dwarf spectra offer vital testbeds for our understanding of the chemical and physical processes that sculpt substellar atmospheres. Recently, atmospheric retrieval approaches have been successfully applied to low-resolution ( R ∼ 100) spectra of L,
Callie E. Hood +3 more
doaj +1 more source
GIANOY-band spectroscopy of dwarf stars: Phosphorus, sulphur, and strontium abundances [PDF]
Astronomy & Astrophysics, 2015 In recent years a number of poorly studied chemical elements, such as phosphorus, sulphur, and strontium, have received special attention as important tracers of the Galactic chemical evolution. By exploiting the capabilities of the infrared echelle spectrograph GIANO mounted at the Telescopio Nazionale Galileo, we acquired high resolution spectra of ...
Ernesto Oliva +9 more
openaire +6 more sources