Search Publications
Stellar and substellar companions of nearby stars from Gaia DR2. Binarity from proper motion anomaly
Mignard, François; Thévenin, Frédéric; Kervella, Pierre +1 more
Context. The census of stellar and substellar companions of nearby stars is largely incomplete, in particular toward the low-mass brown dwarf and long-period exoplanets. It is, however, fundamentally important in the understanding of the stellar and planetary formation and evolution mechanisms. Nearby stars are particularly favorable targets for h…
Abundance to age ratios in the HARPS-GTO sample with Gaia DR2. Chemical clocks for a range of [Fe/H]
Chaplin, W. J.; Moya, A.; Davies, G. R. +8 more
Aims: The purpose of this work is to evaluate how several elements produced by different nucleosynthesis processes behave with stellar age and provide empirical relations to derive stellar ages from chemical abundances.
Methods: We derived different sets of ages using Padova and Yonsei-Yale isochrones and HIPPARCOS and Gaia parallaxes fo…
Gaia Data Release 2. Cross-match with external catalogues: algorithms and results
Marinoni, S.; Marrese, P. M.; Altavilla, G. +1 more
Context. Although the Gaia catalogue on its own is a very powerful tool, it is the combination of this high-accuracy archive with other archives that will truly open up amazing possibilities for astronomical research. The advanced interoperation of archives is based on cross-matching, leaving the user with the feeling of working with one single da…
Stellar population of Sco OB2 revealed by Gaia DR2 data
Micela, G.; Sciortino, S.; Pillitteri, I. +2 more
Context. The Sco OB2 association is the nearest OB association, extending over approximately 2000 square degrees on the sky. Only its brightest and most massive members are already known (from HIPPARCOS) across its entire size, while studies of its lower mass population refer only to small portions of its extent.
Aims: In this work we exploit…
Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2. I. Binarity from proper motion anomaly
Mérand, Antoine; Gieren, Wolfgang; Gallenne, Alexandre +8 more
Context. Classical Cepheids (CCs) and RR Lyrae stars (RRLs) are important classes of variable stars used as standard candles to estimate galactic and extragalactic distances. Their multiplicity is imperfectly known, particularly for RRLs. Astoundingly, to date only one RRL has convincingly been demonstrated to be a binary, TU UMa, out of tens of t…
Barium and related stars, and their white-dwarf companions. II. Main-sequence and subgiant starss
Jorissen, A.; Pourbaix, D.; Escorza, A. +12 more
Barium (Ba) dwarfs and CH subgiants are the less evolved analogues of Ba and CH giants. They are F- to G-type main-sequence stars polluted with heavy elements by their binary companions when the companion was on the asymptotic giant branch (AGB). This companion is now a white dwarf that in most cases cannot be directly detected. We present a large…
Detection and characterisation of 54 massive companions with the SOPHIE spectrograph. Seven new brown dwarfs and constraints on the brown dwarf desert
Bouchy, F.; Deleuil, M.; Moutou, C. +35 more
Context. Brown dwarfs (BD) are substellar objects intermediate between planets and stars with masses of ~13-80 MJ. While isolated BDs are most likely produced by gravitational collapse in molecular clouds down to masses of a few MJ, a non-negligible fraction of low-mass companions might be formed through the planet-formation …
Spectral and orbital characterisation of the directly imaged giant planet HIP 65426 b
Queloz, D.; Quanz, S. P.; Avenhaus, H. +38 more
HIP 65426 b is a recently discovered exoplanet imaged during the course of the SPHERE-SHINE survey. Here we present new L' and M' observations of the planet from the NACO instrument at the VLT from the NACO-ISPY survey, as well as a new Y -H spectrum and K-band photometry from SPHERE-SHINE. Using these data, we confirm the nature of the companion …
Constraining the properties of HD 206893 B. A combination of radial velocity, direct imaging, and astrometry data
Aigrain, S.; Rouan, D.; Meunier, N. +25 more
Context. High contrast imaging enables the determination of orbital parameters for substellar companions (planets, brown dwarfs) from the observed relative astrometry and the estimation of model and age-dependent masses from their observed magnitudes or spectra. Combining astrometric positions with radial velocity gives direct constraints on the o…
Spectroscopic orbits of nearby stars
Tokovinin, A.; Sperauskas, J.; Deveikis, V.
Aims: We observed stars with variable radial velocities to determine their spectroscopic orbits.
Methods: Velocities are presented of 132 targets taken over a time span reaching 30 years. These were measured with the correlation radial velocity spectrometers (1917 velocities) and the new VUES echelle spectrograph (627 velocities), with a…