Planetary systems form two families linked to their stars
A study of 300 well-characterised planetary systems links their architecture to the stars they orbit. Massive, metal-rich stars tend to host wide, heavy systems with signs of turbulent evolution. More compact systems surround stars similar to or smaller than the Sun. The peer-reviewed research examines how formation conditions remain visible after planets change their orbits.
Science··Morning
Stellar properties separate planetary families
An international team led by Italy’s National Institute for Astrophysics, INAF, connected the layout of planetary systems with the properties of their host stars. The peer-reviewed study examined 300 well-characterised systems from more than a thousand known in the Milky Way. Wide, massive systems tend to orbit stars larger than the Sun and richer in elements other than hydrogen and helium. Compact systems cluster around stars similar to or smaller than the Sun.[1], [2]
Wide systems bear traces of turbulent evolution
The wide family often contains between twice and ten times the Solar System’s total planetary mass. Its orbits depart further from a quiet configuration in which planets move on circular paths in a common plane. Researchers associate those departures with gravitational instability, giant collisions and the ejection of planets. In compact systems, planets within the same family have more similar masses and sizes. Many orbit closer to their stars than Mercury does to the Sun.[1]
Simulations test the systems’ starting conditions
Detection methods favour some planets over others, so the researchers examined the role of observational selection in the two groups. Numerical simulations also followed systems from different starting conditions. Configurations unstable from birth best reproduced the dynamical properties of the wide, massive family. The team links this to the greater amount of planet-forming material around those stars. The comparison concerns system architecture and its evolution; it does not identify an inhabited world.[1]
