WASP-18b

WASP-18b orbits extraordinarily close to its host star, completing a full orbit in less than one Earth day, which produces extremely strong tidal interactions between the star and the planet. This makes it one of the best-known real-world laboratories for testing theoretical predictions of tidal dissipation and orbital decay in gas giants.

WASP-18b has an estimated mass of about 10 Jupiter masses, placing it near the boundary between a very massive gas giant and a brown dwarf. Despite its enormous mass, its radius is comparable to Jupiter's because the intense stellar heat inflates the planet's atmosphere.

Yes, WASP-18b is expected to be consumed by its star on timescales that are very short by astronomical standards—potentially within the next few million years. Transit timing observations have been used to measure the rate of its orbital decay, providing one of the few empirical tests of tidal dissipation theory.

WASP-18b was discovered in 2009 by the SuperWASP survey, a ground-based transit-detection project using arrays of wide-angle cameras. The planet was identified by periodic dips in its host star's brightness caused by the planet passing in front of the star from our line of sight.