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A near-infrared excess is detected at the white dwarf PHL5038 in UKIDSS photometry, consistent with the presence of a cool, substellar companion. We have obtained H- and K-grism spectra and images of PHL5038 using NIRI on Gemini North. The…

We present the direct imaging discovery of an extrasolar planet, or possible low-mass brown dwarf, at a projected separation of 55 +/- 2 AU (1.058 +/- 0.007 arcsec) from the B9-type star Kappa And. The planet was detected with Subaru/HiCIAO…

In the course of our search for double degenerate (DD) binaries as potential progenitors of type Ia supernovae with the UVES spectrograph at the ESO VLT (ESO SN Ia Progenitor surveY - SPY) we discovered HE2209-1444 to be a double-lined…

Luhman and collaborators recently discovered an early-T dwarf companion to the G0 dwarf star HN Peg, using Spitzer Infrared Array Camera (IRAC) images. Companionship was established on the basis of the common proper motion inferred from…

We present the results of near-infrared, follow-up imaging and spectroscopic observations at VLT, aimed at characterizing the long-period companions of the exoplanet host stars HD196885, HD1237 and HD27442. The three companions were…

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…

For a decade there has been a factor of 2.5 gap in luminosity between the 275K WISE J085510.83-071442.5 (Luhman 2014) and all other Y dwarfs, with Teff >= 350K. Recently three objects were found which may fall in this gap. Two are…

We present a model atmosphere analysis of ten new DO white dwarfs and five new PG 1159 stars discovered in the Sloan Digital Sky Survey DR1, DR2 and DR3. This is a significant increase in the number of known DOs and PG 1159 stars. DO white…

Young brown dwarfs share many properties with directly imaged giant extrasolar planets. They therefore provide unique laboratories for investigating the full range of temperature and mass encompasses by the growing collection of planets…

We report on Keck and {\em Hubble Space Telescope} observations of the binary millisecond pulsar PSR B1855+09. We detect its white-dwarf companion and measure $\mv=25.90\pm0.12$ and $\mi=24.19\pm0.11$ (Vega system). From the…

Hot subdwarf stars (sdO/Bs) are evolved core helium-burning stars with very thin hydrogen envelopes, which can be formed by common envelope ejection. Close sdB binaries with massive white dwarf (WD) companions are potential progenitors of…

We present a near-infrared spectrum of the close, detached white dwarf + brown dwarf binary WD0137-349 (Maxted et al 2006), that directly reveals the substellar companion through an excess of flux longwards of 1.95 microns. We best match…

We present high-resolution VLT spectra of a new helium-rich DO white dwarf and a new PG1159 star, which we identified in the ESO SPY survey. We performed NLTE model atmosphere analyses and found that the PG1159 star is a low-gravity,…

We present Hubble Space Telescope + Cosmic Origins Spectrograph (HST+COS) data of the eclipsing double white dwarf binary CSS 41177. Due to the temperature difference between the two white dwarfs, the HST+COS far-ultraviolet data are…

We present preliminary results of a study aimed at detecting double white dwarf systems using a method based on a comparison of optical and UV spectra for 141 DA stars drawn from the IUE archives. In particular, we are looking for…

We report on the discovery of the companion star to the millisecond pulsar PSR J1835-3259B in the Galactic globular cluster NGC 6652. Taking advantage of deep photometric archival observations acquired through the Hubble Space Telescope in…

We present ugriz photometry and optical spectroscopy for 28 DB and DO white dwarfs with temperatures between 28,000K and 45,000K. About 10 of these are particularly well-observed; the remainder are candidates. These are the hottest DB stars…

We present the results of a HST/NICMOS coronagraphic survey for the direct detection of substellar companions within the young TW Hydrae and Tucana Associations. At the distance of these associations, the lower mass limit of detection,…

Hot subdwarf B (sdB) stars are post-main-sequence stars of high temperature and gravity. Approximately 30$\%$ of sdBs exhibit stable pressure and/or gravity-mode pulsations, which can be used via the timing method to test for companion…

Based on the astrometry and photometry in Gaia DR3, we identified new nearby white dwarfs and validated those that had been missed from recent white dwarf catalogues despite being previously documented. To ensure the reliability of their…