HAT-P-13 and Its Two Known Planets

HAT-P-13 is a star located 805 light-years away with a spectral type of G4. It has an age of 5 billion years, a mass of 1.22 solar masses, and a radius of 1.56 solar radii. Its reported temperature is 5650 K, cooler than the Sun's, while its mass and radius estimates are both larger than the Sun's. Two planets are known to orbit this host.

HAT-P-13 b is a Jupiter-like planet discovered by the transit method in 2009. Its radius is 14.3 Earth radii, larger than Earth's, and its mass is 270 Earth masses, also larger than Earth's. Its mean density is 0.514 g/cm³, 0.0933 times Earth's. It completes an orbit in 2.92 days, the shortest year among the listed planets by reported estimates.

HAT-P-13 c was discovered by radial velocity in 2009, the same year as its companion. Radial velocity measures the wobble a planet's gravity induces in its star's motion. Its minimum mass is 4540 Earth masses, larger than Earth's and roughly 14.3 times Jupiter's mass. It orbits in 446 days, the longest year among the listed planets by reported estimates.