Related papers: Exploring the planetary-mass population in the Upp…
We have obtained high contrast images of four nearby, faint, and very low mass objects 2MASSJ04351455-1414468, SDSSJ044337.61+000205.1, 2MASSJ06085283-2753583 and 2MASSJ06524851-5741376 (here after 2MASS0435-14, SDSS0443+00, 2MASS0608-27…
We observe 14 young low-mass substellar objects in young moving groups using the SINFONI IFS with LGS-AO to detect and characterize 3 candidate binary systems. Together with the adopted young moving group ages we employ isochrones from…
The mass domain where massive extrasolar planets and brown dwarfs lay is still poorly understood. Indeed, not even a clear dividing line between massive planets and brown dwarfs has been established yet. This is partly due to the paucity of…
We present the discovery of a planetary-mass companion to CFHTWIR-Oph 98, a low-mass brown dwarf member of the young Ophiuchus star-forming region, with a wide 200-au separation (1.46 arcsec). The companion was identified using Hubble Space…
Directly imaged exoplanets in wide orbits challenge current gas giant formation theories. They need to form quickly and acquire enough material before the disk dissipates, which cannot be accommodated by in-situ formation by core accretion.…
We present first results of a survey for companions among X-ray selected pre-main sequence stars, most of them being weak-line T Tauri stars (WTTS). These T Tauri stars have been identified in the course of optical follow-up observations of…
We present K-band photometry and low-resolution near-infrared spectroscopy from 1.44 to 2.45 micron of isolated planetary-mass candidate members in the sigma Orionis cluster found by Zapatero Osorio et al. The new data have been obtained…
We present Keck/OSIRIS 1.1-1.8 um adaptive optics integral field spectroscopy of the planetary-mass companion to GSC 06214-00210, a member of the ~5 Myr Upper Scorpius OB association. We infer a spectral type of L0+/-1, and our spectrum…
We associate 132 low-mass ultracool dwarfs in the southern hemisphere as candidate members of five moving groups using photometric and astrometric selection techniques. Of these objects, we present high resolution spectroscopy for seven…
Aims: Low-resolution optical spectroscopic observations for 78 very low-mass star and brown dwarf candidates that have been photometrically selected using the DENIS survey point source catalogue. Methods: Spectral types are derived for them…
We report the results of a deep near infrared (JHK) survey of the outer parts of the Trapezium Cluster with Gemini South/Flamingos. 396 sources were detected in a 26 arcmin^2 area, including 138 brown dwarf candidates, defined as M<0.075…
In 2022, the James Webb Space Telescope (JWST) obtained 1-5um images of the center of the Orion Nebula Cluster (ONC). I have analyzed these data in an attempt to search for substellar members of the cluster. Using a pair of color-color…
The discovery and characterization of free-floating planetary-mass objects (FFPMOs) is fundamental to our understanding of star and planet formation. Here we report results from an extremely deep spectroscopic survey of the young star…
We found that multi-periodic low-mass stars discovered by Kepler K2 in the Upper Scorpius association are close binaries with typical separations of the order of 10 au and large mass ratios. These stars were surveyed by speckle…
Deep optical imaging is used to study time-domain properties of young brown dwarfs in sigma Orionis over typical rotational time-scales and to search for new substellar and planetary-mass cluster members. We used VIMOS at the VLT to monitor…
We present results from a Hubble Space Telescope imaging search for low-mass binary and planetary companions to 33 nearby brown dwarfs with spectral types of T8-Y1. Our survey provides new photometric information for these faint systems,…
We present the discovery of a substellar companion on a wide orbit around the ~2.5 Msun star HIP 78530, which is a member of the 5 Myr-old Upper Scorpius association. We have obtained follow-up imaging over two years and show that the…
We have performed a survey for substellar companions to young brown dwarfs in the Taurus star-forming region using the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. In these data, we have discovered a candidate…
Context. Though only a handful of extrasolar planets have been discovered via direct imaging, each of these discoveries had tremendous impact on our understanding of planetary formation, stellar formation and cool atmosphere physics. Aims.…
I present infrared spectroscopy of 37 brown dwarf candidates in the Upper Sco association, 35 of which are classified as young and cool, making them likely members. This sample includes many of the faintest spectroscopically confirmed…