Search Publications
Peering into the formation history of β Pictoris b with VLTI/GRAVITY long-baseline interferometry
Förster Schreiber, N. M.; Genzel, R.; Sturm, E. +65 more
Context. β Pictoris is arguably one of the most studied stellar systems outside of our own. Some 30 yr of observations have revealed a highly-structured circumstellar disk, with rings, belts, and a giant planet: β Pictoris b. However very little is known about how this system came into being.
Aims: Our objective is to estimate the C/O ratio i…
The Gaia reference frame for bright sources examined using VLBI observations of radio stars
Lindegren, Lennart
Context. Positions and proper motions of Gaia sources are expressed in a reference frame that ideally should be non-rotating relative to distant extragalactic objects, coincident with the International Celestial Reference System (ICRS), and consistent across all magnitudes. For sources fainter than 16th magnitude, this is achieved through Gaia's d…
Lithium in red giant stars: Constraining non-standard mixing with large surveys in the Gaia era
Jasniewicz, G.; Lagarde, N.; Smiljanic, R. +7 more
Context. Li is extensively known to be a good tracer of non-standard mixing processes occurring in stellar interiors.
Aims: We present the results of a new large Li survey in red giant stars and combine it with surveys from the literature to probe the impact of rotation-induced mixing and thermohaline double-diffusive instability along stella…
A precise architecture characterization of the π Mensae planetary system
Bouchy, F.; Rebolo, R.; Pallé, E. +97 more
Context. The bright star π Men was chosen as the first target for a radial velocity follow-up to test the performance of ESPRESSO, the new high-resolution spectrograph at the European Southern Observatory's Very Large Telescope. The star hosts a multi-planet system (a transiting 4 M⊕ planet at ~0.07 au and a sub-stellar companion on a ~…
Unveiling the β Pictoris system, coupling high contrast imaging, interferometric, and radial velocity data
Genzel, R.; Henning, T.; Meunier, N. +85 more
Context. The nearby and young β Pictoris system hosts a well resolved disk, a directly imaged massive giant planet orbiting at ≃9 au, as well as an inner planet orbiting at ≃2.7 au, which was recently detected through radial velocity (RV). As such, it offers several unique opportunities for detailed studies of planetary system formation and early …
A significant mutual inclination between the planets within the π Mensae system
De Rosa, Robert J.; Nielsen, Eric L.; Dawson, Rebekah
Context. Measuring the geometry of multi-planet extrasolar systems can provide insight into their dynamical history and the processes of planetary formation. These types of measurements are challenging for systems that are detected through indirect techniques such as radial velocity and transit, having only been measured for a handful of systems t…
Properties of carbon stars in the solar neighbourhood based on Gaia DR2 astrometry
de Laverny, P.; Kordopatis, G.; Abia, C. +2 more
Context. Stars evolving along the asymptotic giant branch (AGB) can become carbon rich in the final part of their evolution. The detailed description of their spectra has led to the definition of several spectral types: N, SC, J, and R. To date, differences among them have been partially established only on the basis of their chemical properties. …
Orbital and spectral characterization of the benchmark T-type brown dwarf HD 19467B
Henning, T.; Brandner, W.; Ségransan, D. +42 more
Context. Detecting and characterizing substellar companions for which the luminosity, mass, and age can be determined independently is of utter importance to test and calibrate the evolutionary models due to uncertainties in their formation mechanisms. HD 19467 is a bright and nearby star hosting a cool brown dwarf companion detected with radial v…
A dusty benchmark brown dwarf near the ice line of HD 72946
Absil, O.; Henning, T.; Brandner, W. +12 more
Context. HD 72946 is a bright and nearby solar-type star hosting a low-mass companion at long period (P ∼ 16 yr) detected with the radial velocity (RV) method. The companion has a minimum mass of 60.4 ± 2.2 MJ and might be a brown dwarf. Its expected semi-major axis of ∼243 mas makes it a suitable target for further characterization wit…
A new study of the spectroscopic binary 7 Vul with a Be star primary
Harmanec, P.; Labadie-Bartz, J.; Yang, S. +5 more
We confirmed the binary nature of the Be star 7 Vul, derived a more accurate spectroscopic orbit with an orbital period of 69.d4212±0.d0034, and improved the knowledge of the basic physical elements of the system. Analyzing available photometry and the strength of the Hα emission, we also document the lo…