LHS 1140 and Its Two Known Planets

LHS 1140 is a small, cool red dwarf of spectral type M4.5 V, sitting 48.9 light-years away. It is just 0.184 solar masses and 0.216 solar radii, with a temperature of 3100 K and a reported lower limit of 5 billion years for its age. Its mass, radius, and temperature are all smaller or cooler than the Sun's. Two planets are known to orbit this star.

LHS 1140 b is a Super-Earth discovered by transit in 2017. Its radius is 1.73 Earth radii and its mass is 5.6 Earth masses, both larger than Earth's. It has a mean density of 5.96 g/cm³, 1.08 times Earth's, and completes an orbit in 24.7 days - the longest year among the listed planets.

LHS 1140 c is an Earth-like planet found by transit in 2018. It is smaller than its companion, with a radius of 1.27 Earth radii and a mass of 1.91 Earth masses, both still larger than Earth's. Its mean density is 5.11 g/cm³, 0.928 times Earth's, and its orbital period is 3.78 days - the shortest year and the smallest radius and mass among the listed planets.