We present the discovery of KELT-22Ab , a hot Jupiter from the KELT-South survey .
KELT-22Ab transits the moderately bright ( V \sim 11.1 ) Sun-like G2V star TYC 7518-468-1 .
The planet has an orbital period of P = 1.3866529 \pm 0.0000027 days , a radius of R \textsubscript { P } = 1.285 _ { -0.071 } ^ { +0.12 } ~ { } R \textsubscript { J } , and a relatively large mass of M \textsubscript { P } = 3.47 _ { -0.14 } ^ { +0.15 } ~ { } M \textsubscript { J } .
The star has R \textsubscript { $ \star$ } = 1.099 _ { -0.046 } ^ { +0.079 } ~ { } R \textsubscript { $ \odot$ } , M \textsubscript { $ \star$ } = 1.092 _ { -0.041 } ^ { +0.045 } ~ { } M \textsubscript { $ \odot$ } , T _ { eff } = 5767 _ { -49 } ^ { +50 } K , \log { g _ { \star } } = 4.393 _ { -0.060 } ^ { +0.039 } ( cgs ) and [ m/H ] = +0.259 _ { -0.083 } ^ { +0.085 } , and thus , other than its slightly super-solar metallicity , appears to be a near solar twin .
Surprisingly , KELT-22A exhibits kinematics and a Galactic orbit that are somewhat atypical for thin disk stars .
Nevertheless , the star is rotating quite rapidly for its estimated age , shows evidence of chromospheric activity , and is somewhat metal rich .
Imaging reveals a slightly fainter companion to KELT-22A that is likely bound , with a projected separation of 6″ ( \sim 1400 AU ) .
In addition to the orbital motion caused by the transiting planet , we detect a possible linear trend in the radial velocity of KELT-22A suggesting the presence of another relatively nearby body that is perhaps non-stellar .
KELT-22Ab is highly irradiated ( as a consequence of the small semi-major axis of a / R \textsubscript { $ \star$ } = 4.97 ) , and is mildly inflated .
At such small separations , tidal forces become significant .
The configuration of this system is optimal for measuring the rate of tidal dissipation within the host star .
Our models predict that , due to tidal forces , the semi-major axis of KELT-22Ab is decreasing rapidly , and is thus predicted to spiral into the star within the next Gyr .