WASP-4

WASP-4 is a G-type main-sequence star approximately 891 light-years away in the constellation of Phoenix. Despite its advanced age, the star is rotating rapidly, being spun up by the tides raised by a giant planet on a close orbit.

Planetary system
In 2007 the exoplanet WASP-4b was discovered orbiting this star. With an orbital period of just 1.3 days it is classified as a hot Jupiter. The planet's orbital period appears to be decreasing at a rate of $12.468$ milliseconds per year, suggesting that its orbit is decaying, with a decay timescale of 15.77$12.468$ million years. Another superjovian planet in the system is suspected.