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We present astrometric measurements of eleven nearby ultracool brown dwarfs of spectral types Y and late-T, based on imaging observations from a variety of space-based and ground-based telescopes. These measurements have been used to…

We present initial results from a wide-field (30,000 deg^2) search for L/T transition brown dwarfs within 25 pc using the Pan-STARRS1 and WISE surveys. Previous large-area searches have been incomplete for L/T transition dwarfs, because…

In recent years brown dwarfs have been extended to a new Y-dwarf class with effective temperatures colder than 500K and masses in the range 5-30 Jupiter masses. They fill a crucial gap in observable atmospheric properties between the much…

Solar and Stellar Astrophysics · Physics 2015-06-23 C. G. Tinney , Jacqueline K. Faherty , J. Davy Kirkpatrick , Mike Cushing , Caroline V. Morley , Edward L. Wright

Y dwarfs represent the coldest class of brown dwarfs, with effective temperatures below 500K, and provide unique analogues to cold giant exoplanets. We present a large compilation of uniform near-infrared photometry from the Hubble Space…

We present a UVES/VLT high resolution atlas of three L dwarfs and one T dwarf system, spectral classes at which most of the objects are brown dwarfs. Our atlas covers the optical region from H$\alpha$ up to the near infrared at 1 $\mu$m. We…

Astrophysics · Physics 2009-11-13 A. Reiners , D. Homeier , P. H. Hauschildt , F. Allard

Context: Brown dwarfs exhibit complex atmospheric signatures, and their properties depend sensitively on effective temperature, surface gravity, and metallicity. Several physical properties of brown dwarfs in binary systems can be well…

Astrophysics · Physics 2009-11-13 K. Geißler , G. Chauvin , M. F. Sterzik

We present Spitzer IRAC photometry of twelve very late-type T dwarfs; nine have [3.6], [4.5], [5.8] and [8.0] photometry and three have [3.6] and [4.5] photometry only. We investigate trends with type and color for the planning and…

A large suite of 228 atmospheric retrievals is performed on a curated sample of 19 brown dwarfs spanning the L0 to T8 spectral types using the open-source Helios-r2 retrieval code, which implements the method of short characteristics for…

Earth and Planetary Astrophysics · Physics 2022-05-18 Anna Lueber , Daniel Kitzmann , Brendan P. Bowler , Adam J. Burgasser , Kevin Heng

The application of machine learning principles in the photometric search of elusive astronomical objects has been a less-explored frontier of research. Here we have used three methods: the Neural Network and two variants of k-Nearest…

Solar and Stellar Astrophysics · Physics 2019-07-10 D. Bhavana , S. Vig , S. K. Ghosh , Rama Krishna Sai S. Gorthi

Cold, low-mass, field brown dwarfs are important for constraining the terminus of the stellar mass function, and also for optimizing atmospheric studies of exoplanets. In 2020 new model grids for such objects were made available:…

With the discovery of Y dwarfs by the WISE mission, the population of field brown dwarfs now extends to objects with temperatures comparable to those of Solar System planets. To investigate the atmospheres of these newly identified brown…

Solar and Stellar Astrophysics · Physics 2015-06-23 A. Rajan , J. Patience , P. A. Wilson , J. Bulger , R. J. De Rosa , K. Ward-Duong , C. Morley , F. Pont , R. Windhorst

We investigate applications of machine learning models to directly infer physical properties of brown dwarfs from their photometry and spectra using $\textit{The Cannon}$. We demonstrate that absolute magnitudes, spectral types, and…

Solar and Stellar Astrophysics · Physics 2022-04-06 S. Jean Feeser , William M. J. Best

We present an approach to identifying and characterizing unresolved, very low mass spectral blend binaries composed of late-M, L, and T dwarfs using machine learning methodologies. We generated and evaluated a series of hierarchical random…

We propose a new T, Y dwarf search model using machine learning (ML), called the "BROWn Dwarf Image Explorer (BROWDIE). Brown dwarfs (BD) are estimated to make up 25 percent of all celestial objects in the Galaxy, yet only a small number…

Solar and Stellar Astrophysics · Physics 2024-09-10 Gwujun Kang , Jiwon Lim , Bohyun Seo

The determination of the fundamental properties (mass, separation, age, gravity and atmospheric properties) of brown dwarf companions allows us to infer crucial informations on their formation and evolution mechanisms. Spectroscopy of…

Earth and Planetary Astrophysics · Physics 2020-06-03 D. Mesa , V. D'Orazi , A. Vigan , D. Kitzmann , K. Heng , R. Gratton , S. Desidera , M. Bonnefoy , B. Lavie , A. -L. Maire , S. Peretti , A. Boccaletti

We have identified a sample of cool field brown dwarf candidates using IRAC data from the Spitzer Deep, Wide-Field Survey (SDWFS). The candidates were selected from 400,000 SDWFS sources with [4.5] <= 18.5 mag and required to have…

Benchmark brown dwarfs in wide binary systems are crucial for characterizing substellar objects and calibrating atmospheric and evolutionary models. However, brown dwarf benchmarks with subsolar metallicity, very cool temperatures, or…

We present the discovery of seven new T dwarfs identified in the Two Micron All Sky Survey. Low-resolution (R$\sim$150) 0.8--2.5 micron spectroscopy obtained with the IRTF SpeX instrument reveal the characteristic H$_2$O and CH$_4$ bands in…

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 applied to a number of low-resolution (R~100)…

Solar and Stellar Astrophysics · Physics 2023-07-12 Callie E. Hood , Jonathan J. Fortney , Michael R. Line , Jacqueline K. Faherty

By comparing near-infrared spectra with atmosphere models, we infer the effective temperature, surface gravity, projected rotational velocity, and radial velocity for 21 very-low-mass stars and brown dwarfs. The unique sample consists of…

Solar and Stellar Astrophysics · Physics 2014-11-20 Emily L. Rice , T. Barman , Ian S. McLean , L. Prato , J. Davy Kirkpatrick