WASP-18 is a star with 1.22 times the mass of the Sun, and 1.23 times its radius. It is located 402.75 light years away from the solar system and is estimated to be 1 billion years old, as compared to the Sun which is roughly 4.6 billion years old.
WASP-18 is known to have 2 exoplanets in orbit around it.
WASP-18 b was discovered by the SuperWASP observatory, in 2009-08, using the transit method. Its semi-major axis is 0.02 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of WASP-18 b is 3316.594 times the mass of Earth. The radius of WASP-18 b is 13.350 that of Earth. At more than 50 Earth masses, WASP-18 b is a gas giant, a planet whose mass is mostly made up of hydrogen and helium, like Jupiter and Saturn in our solar system.
WASP-18 c was discovered by the Transiting Exoplanet Survey Satellite (TESS) observatory, in 2019-12, using the transit timing variations method. Its semi-major axis is 0.04 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of WASP-18 c is 55.230 times the mass of Earth. The radius of WASP-18 c is 8.580 that of Earth. At more than 50 Earth masses, WASP-18 c is a gas giant, a planet whose mass is mostly made up of hydrogen and helium, like Jupiter and Saturn in our solar system.