KELT-2Ab

KELT-2Ab is an extrasolar planet that orbits the star KELT-2A approximately 440 light-years away in the constellation of Auriga. It was discovered by the Kilodegree [Extremely Little Telescope|KELT-North] survey via the transit method - so both its mass and radius are known quite precisely - in a paper led by Thomas Beatty. As of its discovery KELT-2Ab is the fifth-brightest transiting Hot Jupiter known that has a well constrained mass. This makes the KELT-2A system a promising target for future space- and ground-based follow-up observations to learn about the planet's atmosphere.
Water vapour was detected in planetary atmosphere in 2018.
The star KELT-2A is a member of the common-proper-motion binary star system KELT-2. KELT-2B is an early K dwarf approximately 295 astronomical units away.