2016MNRAS.459.4281K

We report the discovery of KELT-10b, the first transiting exoplanet discovered using the KELT-South telescope. KELT-10b is a highly inflated sub-Jupiter mass planet transiting a relatively bright V=10.7 star (TYC 8378-64-1), with T_eff=5948±74 K, log g= 4.319_{-0.030}^{+0.020} and [Fe/H]= 0.09_{-0.10}^{+0.11} , an inferred mass M_*= 1.112_{-0.061}^{+0.055} M_☉ and radius R_*= 1.209_{-0.035}^{+0.047} R_☉. The planet has a radius R_p= 1.399_{-0.049}^{+0.069} R_J and mass M_p= 0.679_{-0.038}^{+0.039} M_J. The planet has an eccentricity consistent with zero and a semimajor axis a= 0.052 50_{-0.000 97}^{+0.000 86} au. The best-fitting linear ephemeris is T₀=2457 066.720 45±0.000 27 BJD_TDB and P=4.166 2739±0.000 0063 d. This planet joins a group of highly inflated transiting exoplanets with a larger radius and smaller mass than that of Jupiter. The planet, which boasts deep transits of 1.4 per cent, has a relatively high equilibrium temperature of T_eq= 1377_{-23}^{+28} K, assuming zero albedo and perfect heat redistribution. KELT-10b receives an estimated insolation of 0.817_{-0.054}^{+0.068} x 10⁹ erg/s/cm2, which places it far above the insolation threshold above which hot Jupiters exhibit increasing amounts of radius inflation. Evolutionary analysis of the host star suggests that KELT-10b may not survive beyond the current subgiant phase, depending on the rate of in-spiral of the planet over the next few Gyr. The planet transits a relatively bright star and exhibits the third largest transit depth of all transiting exoplanets with V