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Inside-Out Planetary System Around LHS 1903 Challenges How Planets Form

New Science results point to planets forming sequentially in a gas-poor disk rather than all at once.

Overview

  • A peer-reviewed study published February 12 confirms four close-in planets orbiting the red dwarf LHS 1903 about 116 light-years away.
  • The system’s architecture is rocky–gaseous–gaseous–rocky, with the outer world LHS 1903 e measured at roughly 1.7 Earth radii and consistent with a rocky composition.
  • NASA’s TESS first identified the system, and ESA’s CHEOPS plus multiple ground-based observatories refined planet sizes and orbits, all with periods under 30 days.
  • Dynamical simulations ruled out giant impacts, atmospheric stripping, and planet swapping or migration as sufficient explanations for the observed layout.
  • Researchers propose inside-out, sequential formation in a gas-depleted environment, and experts highlight the system as a target for follow-up, including potential JWST atmospheric studies.