Oral title: The GJ 504 system revisited:  combining high contrast imaging, interferometry, and RV data

Oral abstract: The G-type star GJ504 is known to host a substellar companion whose temperature (Teff~400-600K), 
mass (3-35 MJup), and projected separation (~44 au) all contribute to make it a unique benchmark for the planet 
formation theories and for testing the atmospheric models of giant planets and brown dwarfs at the so-called Y/T 
transition.
We present new VLT/SPHERE deep imaging data on the system. Our 0.9-2.3 µm photometry enables to test the latest 
atmospheric models and to infer new temperature, surface gravity, and metallicity estimates for the companion. We also 
present a new characterization of the host star using CHARA/VEGA interferometric measurements which enable to 
derive a new age estimates for the system and the inclination of the host star. We combine the SPHERE multi-epoch 
detection limits to the long-term (21 years of Lick and SOPHIE data) radial velocy monitoring of the star to set 
unprecedented contraints on the system architecture.  We discuss the system properties and their implications for the 
planet formation and evolution models.