Related papers: Atmospheric, Evolutionary, and Spectral Models of …

A medium resolution 1.0-2.5um spectrum of the brown dwarf, Gliese 229B has been obtained using CGS4 on UKIRT. In addition to the broad spectral structure seen in earlier low resolution observations, the new spectrum reveals a large number…

We present preliminary non-grey model atmospheres and interiors for cool brown dwarfs. The resulting synthetic spectra are compared to available spectroscopic and photometric observations of the coolest brown dwarf yet discovered, Gl229B…

Since October of 1995, employing Doppler spectroscopy astronomers have discovered as many as 20 giant planets and brown dwarfs, including companions to $\tau$ Boo, 51 Peg, $\upsilon$ And, 55 Cnc, $\rho$ CrB, 70 Vir, 16 Cyg B, and 47 UMa.…

We present a spectrum of the cool (T_eff = 900 K) brown dwarf Gliese 229B. This spectrum, with a relatively high signal-to-noise ratio per spectral resolution element (> 30), spans the wavelength range from 0.837 microns to 5.0 microns. We…

Owing to their similarities with giant exoplanets, brown dwarf companions of stars provide insights into the fundamental processes of planet formation and evolution. From their orbits, several brown dwarf companions are found to be more…

Methane brown dwarfs, i.e. objects similar to the low mass star Gliese 229B, are characterized by very unusual colours: J-K<~0 and I-J>~5. An analysis of the ESO public images, which cover an area of 37 sq. arcmin in the three filters,…

We investigate the formation of methane line at 2.3 ${\rm \mu m}$ in Brown Dwarf Gliese 229B. Two sets of model parameters with (a) $T_{\rm eff}=940 $K and $\log (g) =5.0$, (b) $T_{\rm eff}=1030 $K and $ \log(g)=5.5$ are adopted both of…

We present JWST/MIRI low-resolution spectroscopy ($4.75-14~\mu$m) of the first known substellar companion, Gliese 229 Bab, which was recently resolved into a tight binary brown dwarf. Previous atmospheric retrieval studies modeling Gliese…

We combine Keck/HIRES radial velocities, imaging with HiCIAO/Subaru and the Hubble Space Telescope, and absolute astrometry from Hipparcos and Gaia to measure a dynamical mass of $70 \pm 5$ Jupiter masses for the brown dwarf companion to Gl…

We summarize and extend recent work on the theory of extrasolar giant planets (EGPs) and brown dwarfs, paying particular attention to Gliese 229 B, the albedos of EGPs, the compositions of substellar atmospheres, the connections with the…

We calculate detailed chemical abundance profiles for a variety of brown dwarf and extrasolar giant planet atmosphere models, focusing in particular on Gliese 229B, and derive the systematics of the changes in the dominant reservoirs of the…

We report preliminary results of a deep near-infrared search for methane-absorbing brown dwarfs; almost five years after the discovery of Gl 229b, there are only a few confirmed examples of this type of object. New J band, wide-field…

We report the discovery of a widely separated (258$\farcs3\pm0\farcs$4) T dwarf companion to the Gl 570ABC system. This new component, Gl 570D, was initially identified from the Two Micron All Sky Survey (2MASS). Its near-infrared spectrum…

With the discovery of the companions of 51 Peg, 55 Cnc, $\tau$ Boo, $\upsilon$ And, 70 Vir, 47 UMa, and Gl229, evolutionary and spectral models of gas giants and/or brown dwarfs with masses from 0.3 through 60 times that of Jupiter assume a…

We report the discovery of the coolest field dwarf yet known, selected as a stellar object with extremely red colors from commissioning imaging data of the Sloan Digital Sky Survey. Its spectrum from 0.8 to 2.5 microns is dominated by…

We present results from an atmospheric retrieval analysis of Gl 229B using the BREWSTER retrieval code. We find the best fit model to be cloud-free, consistent with the T dwarf retrieval work of Line et al. 2017, Zalesky et al. 2022 and…

We identify the pressure--broadened red wings of the saturated potassium resonance lines at 7700 \AA as the source of anomalous absorption seen in the near-infrared spectra of Gliese 229B and, by extension, of methane dwarfs in general.…

The discovery of the first methane brown dwarf provides a framework for describing the important advances in both fundamental physics and astrophysics that are due to the study of companions of stars. I present a few highlights of the…

We report the discovery of four field methane (T-type) brown dwarfs using 2MASS survey data. One additional methane dwarf, previously discovered by SDSS, was also identified. Near-infrared spectra clearly show the 1.6 and 2.2 um CH4…

The nearby late M star Gliese 569B was recently found by adaptive optics imaging to be a double with separation ~1 AU. To explore the orbital motion and masses, we have undertaken a high resolution (~0.05 arcsec) astrometric study. Images…