WASP-19b is an extrasolar planet

Extrasolar planet

An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...

, notable for possessing the shortest orbital period of any known planetary body: 0.7888399 days or approximately 18.932 hours.
It has a mass close to that of Jupiter

Jupiter

Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

 (1.15 Jupiter mass

Jupiter mass

Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....

es), but by comparison has a much larger radius (1.31 times that of Jupiter, or 0.13 Solar radii); making it nearly the size of a low-mass star. It orbits the star WASP-19a in the Vela constellation.