Related papers: Mapping the Shores of the Brown Dwarf Desert I.: U…
The Upper Scorpius OB association is the nearest region of recent massive star formation and thus an important benchmark for investigations concerning stellar evolution and planet formation timescales. We present nine EBs in Upper Scorpius,…
We are studying the influence of stellar multiplicity on exoplanet systems, in particular systems that have been detected via radial-velocity searches. We are in particular interested in the closest companions as they would have a strong…
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 report on initial results from a Spitzer program to search for very low-mass brown dwarfs in Ophiuchus. This program is an extension of an earlier study by Allers et al. which had resulted in an extraordinary success rate, 18 confirmed…
Searches for companions of brown dwarfs by direct imaging mainly probe orbital separations > 3-10 AU. On the other hand, previous radial velocity surveys of brown dwarfs are mainly sensitive to separations smaller than 0.6 AU. It has been…
Distinguishing classes within substellar objects and understanding their formation and evolution need larger samples of substellar companions such as exoplanets, brown dwarfs, and low-mass stars. In this paper, we look for substellar…
We present a 3-5um LBT/MMT adaptive optics imaging study of three Upper Scorpius stars with brown dwarf (BD) companions with very low-masses/mass ratios (M_BD < 25M_Jup; M_BD / M_star ~ 1-2%), and wide separations (300-700 AU): GSC 06214,…
We present the first statistical analysis of exoplanet direct imaging surveys combining adaptive optics imaging at small separations with deep seeing-limited observations at large separations allowing us to study the entire orbital…
Almost all massive stars are part of a binary system. Given the wide range of separations at which these companions are found, several observational techniques have been adopted to characterize them, but contrasts greater than 4 in the…
We present the discovery of 61 wide (>5 arcsecond) separation, low-mass (stellar and substellar) companions to stars in the solar neighborhood identified from Pan-STARRS\,1 (PS1) data and the spectral classification of 27 previously known…
Giant planets are usually thought to form within a few tens of AU of their host stars, and hence it came as a surprise when we found what appeared to be a planetary mass (~0.008 Msun) companion around the 5 Myr-old solar mass star 1RXS…
Astrometric measurements are presented for seven nearby stars with previously detected planets: six M dwarfs (GJ 317, GJ 667C, GJ 581, GJ 849, GJ 876, and GJ 1214) and one K dwarf (BD $-$10 3166). Measurements are also presented for six…
In recent decades, thousands of substellar companions have been discovered with both indirect and direct methods of detection. In this paper, we focus our attention on substellar companions detected with the direct imaging technique, with…
We report on a deep photometric survey covering an area of 1.17 deg$^2$ in the young Upper Scorpius stellar association using VIMOS $Iz$ and UKIDSS $ZJHK$ data taking several years apart. The search for the least massive population of Upper…
We present a near-infrared photometric search for unresolved substellar companions and debris disks around white dwarfs in the UKIRT Infrared Deep Sky Survey Large Area Survey. We cross-correlate the SDSS DR4 and McCook & Sion catalogues of…
We present the results of a radial velocity (RV) survey of 14 brown dwarfs (BDs) and very low-mass (VLM) stars in the Upper Scorpius OB association (UScoOB) and 3 BD candidates in the rho Ophiuchi dark cloud core. We obtained…
A combination of high-resolution and wide-field imaging reveals two binary stars and one triple star system among the sample of the first 11 stars with planets detected by radial velocity variations. High resolution speckle or adaptive…
I review here the results of the first RV survey for spectroscopic companions to very young brown dwarfs (BDs) and (very) low-mass stars in the ChaI star-forming cloud with UVES at the VLT. This survey studies the binary fraction in an as…
We report the discovery of three low-mass double-lined eclipsing binaries in the pre-main sequence Upper Scorpius association, revealed by $K2$ photometric monitoring of the region over $\sim$ 78 days. The orbital periods of all three…
Aims. The project aims to understand better the role of wide brown dwarf companions on planetary systems. Methods. We obtained high-resolution spectra of six bright stars with co-moving wide substellar companions with the SONG, CARMENES,…