GIant Planetary Systems Exploration – GIPSE

Giant planets (GP) are major players in the building-up of planetary systems; a good knowledge of the giant planet population is then necessary to get a full understanding of planetary system formation and evolution. Yet, we have only a very partial view of the extrasolar GP populations, because RV/transit technics are sensitive to planets close to the stars, and up to now, direct imaging techniques were sensitive to far away planets (> 10 AU tyP.). Moreover indirect and direct techniques do not consider the same targets (MS stars for the indirect and young stars for the direct techniques). For no star do we have today a complete exploration of its giant planet population today. A solar-system analogue is out of reach of present detection capabilities, for telluric planets, but also for giant planets, and a full exploration of the GP population around mature, solar-type MS stars will not be possible before one or two decades.

We propose here to bridge the present gap for the first time. To do so, we will 1/ undertake the first complete exploration of giant planets, from tenths to hundreds of AUs around a well-chosen sample of young stars, 2/ derive quantitative statistical information on GPs properties, 3/ deduce constraints on GP formation and early (first hundreds Myrs) evolution mechanisms, and 4/ perform detailed various studies of individual systems.

Our project is now possible thanks to two concomitant progresses: the arrival of high performance planet imagers, dedicated to the detection and characterization of planets around young stars on the one hand, and, on the other hand, the maturity of the analysis techniques of radial velocity data that allow now searching for planets around young (and active) stars. We have selected a sample of stars in nearby, young stellar associations that are suited for both radial velocity studies and direct imaging.

Thanks to these unique results, we will constrain the processes of planetary system formation (prevalence of core accretion versus gravitational instability within a disk, constraints on initial conditions), the evolution processes (disk-planet migration versus planet-planet interaction), and their associated timescales. Detailed studies will also help understanding individual systems. Such studies are proven to be very precious to progress in the field so far.

Our team has a strong experiment and records in high contrast imaging of exoplanets on the one hand (PI/PS of NACO and forthcoming SPHERE on the VLT; discovery and studies of several exoplanets in direct imaging), as well as in radial velocity techniques (development and successful use of tools that allow to measure precise radial velocities of rapidly rotating stars, discoveries of radial velocity planets, feasibility study of the detection of giant planets around young -and active- stars; quantitative studies of the impact of stellar/solar activity on the detectability of exoplanets).