Related papers: The discovery of a very cool binary system

Ultra-cool dwarfs as wide companions to subgiants, giants, white dwarfs and main sequence stars can be very good benchmark objects, for which we can infer physical properties with minimal reference to theoretical models, through association…

We present observations of a new very low mass field binary, discovered during an infrared imaging survey of 250 DENIS L and very late-M dwarfs. DENIS-J055146.0-443412.2 is an M8.5+L0 pair, with a physical separation of over 200 AU. This…

We present near-infrared spectra for a sample of T dwarfs, including eleven new discoveries made using the Two Micron All Sky Survey. These objects are distinguished from warmer (L-type) brown dwarfs by the presence of methane absorption…

We present the spectroscopic analysis of a large sample of late-M, L, and T dwarfs from UKIDSS. Using the YJHK photometry from ULAS and the red-optical photometry from SDSS we selected a sample of 262 brown dwarf candidates and we…

We have discovered that the extremely red, low-gravity L7 dwarf 2MASS J11193254-1137466 is a 0.14" (3.6 AU) binary using Keck laser guide star adaptive optics imaging. 2MASS J11193254-1137466 has previously been identified as a likely…

We present IRTF SpeX observations of the M/L binary system 2MASS J17072343-0558249. SpeX imaging resolves the system into a 1"01+/-0.17 visual binary in which both components have red near infrared colors. Resolved low-resolution (R~150)…

We present new JHKL'M' photometry on the MKO system for a large sample of L and T dwarfs identified from SDSS and 2MASS and classified according to the scheme of Geballe et al. (2002). We have compiled a sample of 105 L and T dwarfs that…

WISE J104915.57-531906.1 A+B and WISE J085510.83-071442.5 were recently discovered as the third and fourth closest known systems to the Sun, respectively (2.0 and 2.3 pc). The former consists of a L8+T0.5 binary and the latter is a probable…

We present the results of an intense photometric monitoring in the near-infrared (~0.9 microns) with the TRAPPIST robotic telescope of the newly discovered binary brown dwarf WISE J104915.57-531906.1, the third closest system to the Sun at…

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…

We report the discovery of a wide (approximately 400 AU projected separation), common proper motion companion to the nearby M dwarf LHS 2803 (PSO J207.0300-13.7422). This object was discovered during our census of the local T dwarf…

We present the discovery of a companion to the Y-dwarf, CWISEP J193518.59-154620.3, the second Y-Y dwarf binary detected to date. Y-dwarfs are the coldest known free-floating objects ($<$ 500 K) and on average represent the lowest mass…

We report the discovery of the ultracool dwarf binary system J1250+0455AB, a low-mass (M$_\odot$$_\mathrm{tot} <$ 0.2 M$_\odot$) system in which the components straddle the M/L dwarf boundary. The binary was resolved through near-infrared…

We present 0.9 - 2.5 um resolved spectra for the ultracool binary WISEPC J121756.91+162640.2AB. The system consists of a pair of brown dwarfs that straddles the currently defined T/Y spectral type boundary. We use synthetic spectra…

We report on nine wide common proper motion systems containing late-type M, L, or T companions. We confirm six previously reported companions, and identify three new systems. The ages of these systems are determined using diagnostics for…

We report the discovery of the coolest subdwarf reported to date. The star LSR1425+7102 was discovered in our survey for faint high proper motion stars in the northern sky. Follow-up spectroscopy revealed the star to be a very red object…

We present Keck II laser guide star adaptive optics observations of the brown dwarf WISEP J061135.13-041024.0 showing it is a binary with a component separation of 0.4". This system is one of the six known resolved binaries in which the…

Ultra-cool white dwarfs are among the oldest stellar remnants in the Universe. Their efficient gravitational settling and low effective temperatures are responsible for the smooth spectra they exhibit. For that reason, it is not possible to…

Astrometric observations of resolved binaries provide estimates of orbital periods and will eventually lead to measurement of dynamical masses. Only a few very low mass star and brown dwarf masses have been measured to date, and the…

Binaries provide empirical key constraints for star formation theories, like the overall binary fraction, mass ratio distribution and the separation distribution. They play a crucial role to calibrate the output of theoretical models, like…