CHEOPS Reveals 'Inside-Out' Four-Planet System Around Red Dwarf LHS 1903

Overview

• LHS 1903, a red dwarf about 116 light-years away, hosts four planets ordered rocky, gaseous, gaseous, then rocky.
• The outer planet, LHS 1903 e, measures roughly 1.7 times Earth’s radius and appears to be a dense, rocky super-Earth.
• NASA’s TESS first flagged the system, and ESA’s CHEOPS with ground-based telescopes refined planet sizes and confirmed the unusual architecture.
• Dynamical tests do not support explanations based on giant impacts, atmospheric stripping, or large-scale orbital rearrangement.
• The research team favors sequential formation after disk gas depletion, while outside experts highlight the need for atmospheric observations, potentially with JWST, to test the scenario.