Kepler-129: A Sun-Like Star and Its Three Worlds

Kepler-129 is a G-type main-sequence star 1330 light-years away. Its spectral type, G4 V, marks it as a Sun-like dwarf, and it is older than the Sun at 8.91 billion years. It is also somewhat larger and more massive than the Sun, with 1.07 solar masses and 1.56 solar radii, and cooler, at a temperature of 5530 K. The system has one cataloged star, and three planets are known to orbit this star.

Kepler-129 b is a Super-Earth discovered by the transit method in 2014. Its radius is 2.4 Earth radii, larger than Earth's, and it completes an orbit every 15.8 days, the shortest orbital period among the listed planets. Its minimum mass carries a reported upper limit of 20 Earth masses.

Kepler-129 c, a Neptune-like planet also found by transit in 2014, has a radius of 2.52 Earth radii and a mass of 43 Earth masses, both larger than Earth's. Its mean density is 14.8 g/cm³, 2.69 times Earth's. It orbits every 82.2 days, the second-shortest orbital period among the listed planets.

Kepler-129 d was discovered in 2021 by the radial velocity method, which detects the wobble a planet's gravity induces in its star. It has a minimum mass of 2640 Earth masses, roughly 8.3 times Jupiter's mass and larger than Earth's, and its orbital period is 2650 days, the longest among the listed planets.