Seminars at FGG
Searching for natural satellites around directly imaged giant exoplanets and brown dwarfs with the radial velocity technique
Speaker: Ilaria Giovannini (University of Padova, Italy)
Date and time: 2026-09-28 11:00
Nowadays, almost 6000 planets outside our Solar System have been detected with a plethora of different techniques. Despite the fact that the Solar System contains more than 400 moons, no natural satellite has been confirmed around any exoplanet. Satellites are objects orbiting around an exoplanet or a brown dwarf that help us understand the formation and dynamical evolution of their system. My research investigates the potential for detecting satellite companions. We collected spatially resolved giant exoplanets and brown dwarfs from NASA and ESA archives that showed characteristics suitable for satellite detection through radial velocity (RV). This is a cutting-edge technique, as it extracts the RV measure from the high-resolution spectrum of the planet itself, rather than the host star’s. Radial velocity signals induced by natural satellites are indeed of the order of 300-500 m/s. We estimated the expected RV precision for each target to understand the detection limits of CRIRES+ and HiRISE at VLT, as well as future facilities like ANDES at ELT. This approach has been proven successful by a recent 0.9 MJ satellite detection around a substellar companion at a separation of 0.2 AU through CRIRES+. Even if this research approach is already effective, the potential for detecting satellites will expand towards fainter objects with ANDES and next-generation telescopes like ELT are crucial if we aim to find the first ever Earth-like exomoon. An extensive analysis of the capabilities of these new instruments before their first-light is essential to be prepared for when they will be available to the community.