TOI-1338 A and Its Two Circumbinary Planets

TOI-1338 A is an F-type star located 1300 light-years away. Its spectral type of F8 places it in a temperature class hotter than the Sun's G-type, and its reported temperature of 6050 K is likewise hotter than the Sun's. The star's reported mass of 1.13 solar masses and radius of 1.33 solar radii are both larger than the Sun's. It is estimated to be 4.4 billion years old. Two planets are known to orbit this host, and both are circumbinary, orbiting both stars of the binary system rather than one star alone.

TOI-1338 b was discovered in 2020 by the transit method, which detects the small dip in brightness when a planet passes in front of its star; repeated dips help establish orbital periods. This Jupiter-like planet has a radius of 7.66 Earth radii, larger than Earth's, and a mass of 11.3 Earth masses, also larger than Earth's. Its mean density is 0.138 g/cm³. It completes an orbit in 95.4 days.

TOI-1338 c was discovered in 2023 using the radial velocity method, which measures the wobble a planet's gravity induces in its star's motion, with repeated wobbles revealing the planet and its orbital period. Its mass of 75.4 Earth masses is larger than Earth's, and it orbits once every 216 days. Neither planet's radius is reported for TOI-1338 c, and no period is listed beyond the 216 days given for its orbit.