We announce the discovery of KELT-23Ab , a hot Jupiter transiting the relatively bright ( V = 10.3 ) star BD+66 911 ( TYC 4187-996-1 ) , and characterize the system using follow-up photometry and spectroscopy .
A global fit to the system yields host-star properties of T _ { eff } = 5900 \pm 49 K , M _ { * } = 0.945 ^ { +0.060 } _ { -0.054 } M _ { \Sun } , R _ { * } = 0.995 \pm 0.015 R _ { \Sun } , L _ { * } = 1.082 ^ { +0.051 } _ { -0.048 } L _ { \Sun } , \log { g _ { \star } } = 4.418 ^ { +0.026 } _ { -0.025 } ( cgs ) , and \left [ { Fe } / { H } \right ] = -0.105 \pm 0.077 .
KELT-23Ab is a hot Jupiter with mass M _ { P } = 0.938 ^ { +0.045 } _ { -0.042 } M _ { J } , radius R _ { P } = 1.322 \pm 0.025 R _ { J } , and density \rho _ { P } = 0.504 ^ { +0.038 } _ { -0.035 } g cm ^ { -3 } .
Intense insolation flux from the star has likely caused KELT-23Ab to become inflated .
The time of inferior conjunction is T _ { 0 } = 2458149.40776 \pm 0.00091 ~ { } { BJD _ { TDB } } and the orbital period is P = 2.255353 ^ { +0.000031 } _ { -0.000030 } days .
There is strong evidence that KELT-23A is a member of a long-period binary star system with a less luminous companion , and due to tidal interactions , the planet is likely to spiral into its host within roughly a Gyr .
This system has one of the highest positive ecliptic latitudes of all transiting planet hosts known to date , placing it near the Transiting Planet Survey Satellite and James Webb Space Telescope continuous viewing zones .
Thus we expect it to be an excellent candidate for long-term monitoring and follow-up with these facilities .