KELT-2Ab

KELT-2Ab is an extrasolar planet that orbits the star KELT-2A approximately 440 light-years away in the constellation of Auriga.^[1] It was discovered by the 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.^[3]

KELT-2Ab

Discovery
Discovered by	T. G. Beatty et al.
Discovery date	7 June 2012
Detection method	Transit
Orbital characteristics
Semi-major axis	0.5504 ± 0.00086 AU (82,339,000 ± 129,000 km)
Eccentricity	0
Orbital period (sidereal)	4.1137913 ± 0.00001 d
Inclination	88.56 ± 1.14
Time of periastron	2455974.60338 ± 0.00083
Argument of periastron	90
Semi-amplitude	161.1 ± 7.8
Star	KELT-2A
Physical characteristics
Mean radius	1.290 ± 0.057[1] RJ
Mass	1.524 ± 0.088[1] MJ
Mean density	0.940 ± 0.090 g/cm3[1]
Surface gravity	22.7 m/s2 (74 ft/s2) 2.3 g
Temperature	1994±104 K or 1782±111 K[2]

Water vapour was detected in planetary atmosphere in 2018.^[4]

The star KELT-2A is a member of the common-proper-motion binary star system KELT-2 (HD 42176). KELT-2B is an early K dwarf approximately 295 astronomical units away.

See also

• KELT
• KELT-9b
• KELT-1
• KELT-10
• KELT-11b