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Inside-Out Exoplanet System Around Red Dwarf LHS 1903 Challenges Formation Models

Researchers report in Science that the outer planet likely formed late in a depleted disk.

Overview

  • An international team confirms four planets around LHS 1903 with the sequence rock, gas, gas, rock.
  • CHEOPS transit radii combined with HARPS-N radial-velocity masses show the outer planet, LHS 1903 e, has a rocky composition.
  • The configuration conflicts with photoevaporation and thermally driven mass-loss expectations that predict gas-rich worlds farther out.
  • The authors favor a Gas-Depleted Formation scenario in which the outer world formed when little nebular gas remained.
  • TESS first flagged the system around the red dwarf about 116 light-years away, with orbits spanning roughly 2 to 30 days.