Host Stars Shape Planetary Systems into Two Distinct Families

• Researchers analyzed 300 well-characterized multi-planet systems and identified two distinct architectural families.
• The characteristics of the host star play a critical role in shaping the "genetic" development and final structure of its planetary system.

The Two Planetary Families

• Lower-Mass Systems:
  • Hosted by stars with masses equal to or lower than the Sun.
  • Feature "peas-in-a-pod" configurations where neighboring planets have similar sizes and masses.
  • Exhibit low orbital eccentricity and inclination, characterizing them as "cold" systems with less violent dynamical histories.
• High-Mass Systems:
  • Form in metal-rich environments around solar-to-supersolar stars.
  • Feature wider orbits with a combined mass two to ten times that of our Solar System.
  • Display high dynamical excitation, meaning more eccentric and inclined orbits caused by violent planet-planet scattering and global instabilities, marking them as "hot" systems.

Methodology and Implications

• The team used the Normalized Angular Momentum Deficit (NAMD) to measure the dynamical history of these systems; higher NAMD values indicate more violent interactions.
• This research rejects the long-held assumption that our Solar System is a universal template for all planetary architectures.
• Findings suggest that the fate of a planetary system is determined by a combination of birth conditions—governed by the host star—and subsequent evolutionary pathways.