Kepler-539 and Its Two Worlds

Kepler-539 is a G2 V star, a Sun-like main-sequence dwarf, located 1000 light-years away. Its reported mass is 1.05 solar masses, its reported radius is 0.952 solar radii, and its temperature is 5820 K. Two planets are known to orbit this host.

Both planets were discovered in 2016 by the transit method, which detects the small dip in a star's brightness when a planet crosses in front of it. Kepler-539 b is a Jupiter-like planet with a radius of 8.37 Earth radii, larger than Earth's, and a mass of 308 Earth masses, also larger than Earth's. Its mean density is 2.89 g/cm³, 0.525 times Earth's. It completes an orbit every 126 days. Among the listed planets, Kepler-539 b has the smallest reported mass.

Kepler-539 c was found through transit timing variations, in which slight shifts in a transiting planet's schedule reveal the pull of a companion. Its mass is 763 Earth masses, larger than Earth's and roughly 2.4 times Jupiter's mass. Its orbital period is a reported lower limit of 1000 days. Among the listed planets, Kepler-539 c has the largest reported mass.