LHS 1903: A Cool Red Dwarf with Four Known Planets

LHS 1903 is a small, cool red dwarf star located 116 light-years away. Its spectral type is M, and it has an age of 7.08 billion years. The star's mass is 0.538 solar masses, its radius is 0.539 solar radii, and its reported temperature is 3660 K, all smaller or cooler than the Sun's corresponding values. Four planets are known to orbit this host: LHS 1903 b, c, d, and e. All four were discovered by the transit method in 2026.

LHS 1903 b is an Earth-like planet with a mass of 3.28 Earth masses and a radius of 1.38 Earth radii. Its mean density is 6.85 g/cm³, 1.24 times Earth's. It completes an orbit every 2.16 days, the shortest year among the listed planets.

LHS 1903 c is a Super-Earth with an mass of 4.55 Earth masses and an radius of 2.05 Earth radii. Its mean density is 2.93 g/cm³, 0.531 times Earth's. Its orbital period is 6.23 days, the second-shortest year among the listed planets.

LHS 1903 d is a Neptune-like planet with an mass of 5.96 Earth masses and an radius of 2.5 Earth radii. Its mean density is 2.1 g/cm³, 0.381 times Earth's. Its orbital period is 12.6 days, the second-longest year among the listed planets.

LHS 1903 e is a Super-Earth with an mass of 5.79 Earth masses and an radius of 1.73 Earth radii. Its mean density is 6.14 g/cm³, 1.11 times Earth's. It orbits every 29.3 days, the longest year among the listed planets.