Radial velocities & light curves of KELT-24

The host star, KELT-24 (HD 93148), has a T_eff_=6509_-49_^+50^ K, a mass of M_*_=1.460_-0.059_^+0.055^ M_{sun}_, a radius of R_*_=1.506+/-0.022 R_{sun}_, and an age of 0.78_-0.42_^+0.61^ Gyr. Its planetary companion (KELT-24 b) has a radius of R_P_=1.272+/-0.021 R_J_ and a mass of M_P_=5.18_-0.22_^+0.21^ M_J_, and from Doppler tomographic observations, we find that the planet's orbit is well-aligned to its host star's projected spin axis ({lambda}=2.6_-3.6_^+5.1^).

The young age estimated for KELT-24 suggests that it only recently started to evolve from the zero-age main sequence. KELT-24 is the brightest star known to host a transiting giant planet with a period between 5 and 10 days. Although the circularization timescale is much longer than the age of the system, we do not detect a large eccentricity or significant misalignment that is expected from dynamical migration.