Related papers: AB Doradus C: Age, Spectral Type, Orbit, and Compa…

The aim of the Degenerate Objects around Degenerate Objects (DODO) survey is to search for very low mass brown dwarfs and extrasolar planets in wide orbits around white dwarfs via direct imaging. The direct detection of such companions…

We present detailed evolutionary calculations for carbon - oxygen - and helium - core white dwarf (WD) models with masses ranging from M= 0.1 to M= 1.2 solar masses and for metallicities Z= 0.001 and Z= 0. The sequences cover a wide range…

GJ 229B, the first type-T brown dwarf to be discovered, has presented a tension between comparisons with evolutionary models and the larger-than-expected mass and radius values derived from spectroscopic and astrometric observations. We…

We present a spectral analysis of the Hubble Space Telescope Cosmic Origins Spectrograph spectrum of the southern VY Scl nova-like variable BB Doradus, obtained as part of a Cycle 20 {\it HST/COS} survey of accreting white dwarfs in…

The origin of the very red optical and infrared colours of intermediate-age ($\sim$10 - 500 Myr) L-type dwarfs remains unknown. It has been suggested that low-gravity atmospheres containing large amounts of dust may account for the observed…

We present evolutionary models for young low mass stars and brown dwarfs taking into account episodic phases of accretion at early stages of the evolution, a scenario supported by recent large surveys of embedded protostars. An evolution…

With a uniform VLT SINFONI data set of nine targets, we have developed an empirical grid of J,H,K spectra of the atmospheres of objects estimated to have very low substellar masses of \sim5-20 MJup and young ages of \sim1-50 Myr. Most of…

We measure dynamical masses for five objects--three ultracool dwarfs, one low-mass star, and one white dwarf--by fitting orbits to a combination of the Hipparcos-Gaia Catalog of Accelerations, literature radial velocities, and relative…

We report individual dynamical masses for the brown dwarfs Epsilon Indi B and C, which have spectral types of T1.5 and T6, respectively, measured from astrometric orbit mapping. Our measurements are based on a joint analysis of astrometric…

We aim to reveal the nature of the reddest known substellar companion HD 206893 B by studying its near-infrared colors and spectral morphology and by investigating its orbital motion. We fit atmospheric models for giant planets and brown…

We present analyses of high resolution and medium resolution spectra of early L dwarfs. We used our latest set of model atmospheres to reproduce and analyze the observed features. We can model the optical flux and the atomic line profiles…

We present near-infrared photometry and spectroscopy, and warm-Spitzer IRAC photometry of the young very cool T dwarf Ross 458C, which we have typed as T8.5p. By applying the fiducial age constraints (< 1Gyr) imposed by the properties of…

Recent observations point to the presence of structured dust grains in the discs surrounding young brown dwarfs, thus implying that the first stages of planet formation take place also in the sub-stellar regime. Here, we investigate the…

We performed a radial velocity (RV) monitoring of the 40 Myr old star DS Tuc A with HARPS at the ESO-3.6m to determine the planetary mass of its 8.14-days planet, first revealed by TESS. We also observed two planetary transits with HARPS…

We present the detection of [$3.6~\mu$m] photometric variability in two young, L/T transition brown dwarfs, WISE J004701.06+680352.1 (W0047) and 2MASS J2244316+204343 (2M2244) using the \textit{Spitzer Space Telescope}. We find a period of…

The masses of compact objects like white dwarfs, neutron stars and black holes are fundamental to astrophysics, but very difficult to measure. We present the results of an analysis of subluminous B (sdB) stars in close binary systems with…

We present observations of Halpha emission line profiles taken at Magellan Observatory for a sample of 39 young low-mass stars and brown dwarfs in the Taurus and Chamaeleon I star forming regions. We have identified 11 new substellar…

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:…

Aims: Our objective is the optical and near-infrared spectroscopic characterisation of 2MASS J0249-0557 c, a recently discovered young planetary mass companion to the $\beta$ Pictoris member 2MASS J0249-0557. Methods: Using the Visible and…

We observed eclipses of the transiting brown dwarf CWW 89Ab at 3.6um and 4.5um using Spitzer/IRAC. The CWW 89 binary system is a member of the $3.0\pm0.25$ Gyr-old open cluster Ruprecht 147, and is composed of a Sun-like primary and an…