Stellar clustering shapes the architectures of planetary systems

Abstract

Planet formation is generally described in terms of a system containing the host star and a protoplanetary disc 1-3 , of which the internal properties (e.g. mass and metallicity) determine the properties of the resulting planetary system 4 . However, (proto)planetary systems are predicted 5, 6 and observed 7, 8 to be affected by the spatially-clustered stellar formation environment, either through dynamical star-star interactions or external photoevaporation by nearby massive stars 9 . It is challenging to quantify how the architecture of planetary systems is affected by these environmental processes, because stellar groups spatially disperse within <1 billion years 10 , well below the ages of most known exoplanets. Here we identify old, co-moving stellar groups around exoplanet host stars in the astrometric data from the Gaia satellite 11,12 and demonstrate that the architecture of planetary systems exhibits a strong dependence on local stellar clustering in position-velocity phase space, implying a dependence