WASP-1
WASP-1 is a magnitude 12 binary star system located about light-years away in the Andromeda constellation. The binary system consists of a metal-rich F-type main-sequence star, named WASP-1A, and a distant low-mass star, named WASP-1B. WASP-1A has one known transiting hot Jupiter exoplanet named WASP-1b.
Stellar companion
WASP-1A has a distant companion star, named WASP-1B. WASP-1B is a low-mass star that is around 0.3 times as massive as the Sun and has an effective temperature of about. WASP-1B is located northward of WASP-1A at an angular separation of about 4.6 arcseconds, corresponding to a projected distance of 1587 AU. WASP-1B was first identified in observations from 2006 and confirmed in further observations from 2012 to 2014, which showed that it shares the proper motion of WASP-1A, indicating the two stars are gravitationally bound to each other.Planetary system
In 2006, an extrasolar planet was discovered by the Wide Angle Search for Planets team using the transit method. The planet has a density of 0.31 to 0.40 g/cm3, making it about half as dense as Saturn, and one third as dense as water. The orbit of WASP-1b is inclined to the rotational axis of the star by 79.0 degrees, making it a nearly "polar" orbit.Two searches for additional planets using transit-timing variations have yielded negative results.