Yale Astronomy Virtual Colloquium - Damien Ségransan

Event time: 
Thursday, April 29, 2021 - 2:30pm
Damien Ségransan
Speaker Institution: 
University of Geneva (Université de Genève)
Talk Title: 
Probing the architecture of planetary systems using radial velocities, astrometry and direct imaging.
Event description: 

Characterizing the global architecture of planetary systems is crucial to understand their formation history and dynamical evolution. While more than 4000 exoplanets have already been detected, it remains extremely challenging to fully characterize both the inner and outer regions of planetary systems due to the disparate planetary orbital periods ranging from hours to decades, and to the detection limits and biases of the different observing methods (transit, radial velocities, and imaging). Thus, the coupling between the inner and outer parts of planetary systems, during the formation of the planets and their subsequent evolution, remains poorly constrained by observations. The situation is however changing thanks to ongoing and forthcoming large scale radial velocity surveys, the expected release of a substellar companions catalog for GAIA DR3&4 and synergies with high contrast imaging programmes to image cool companions to nearby solar type stars.

I will first revisit a multiple planet system discovered with HARPS to illustrate the need to constantly improve our statistical methods to search for and hopefully detect Earth-analogs using radial velocities. I will then present the latest results from the 22-year-long CORALIE radial velocity survey and  estimate the occurence of massive giant planets and brown dwarfs companions up to 5 AU. As a teaser, and based on real GAIA astrometric time series, I will show how the astrometric mission will contribute to this science case. For separations larger than 5 AU, the CORALIE survey also provides ultra-cool companion candidates to be imaged using the SPHERE high contrast imaging instrument located at ESO/Paranal.