We present the discovery of KELT-24 b, a massive hot Jupiter orbiting a bright (V = 8.3 mag, K = 7.2 mag) young F-star with a period of 5.6 days. The host star, KELT-24 (HD 93148), has a Teff = 6509-+4950 K, a mass of M* = 1.460-+0.0590.055 Me, a radius of R* = 1.506 ± 0.022 Re, and an age of 0.78-+0.420.61 Gyr. Its planetary companion (KELT-24 b) has a radius of RP = 1.272 ± 0.021 RJ and a mass of MP = 5.18-+0.220.21 MJ, and from Doppler tomographic observations, we find that the planet’s orbit is well-aligned to its host star’s projected spin axis (l = 2.6-+3.65.1). 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. The brightness of its host star and its moderate surface gravity make KELT-24b an intriguing target for detailed atmospheric characterization through spectroscopic emission measurements since it would bridge the current literature results that have primarily focused on lower mass hot Jupiters and a few brown dwarfs.
Publication Source (Journal or Book title)
Rodriguez, J., Eastman, J., Zhou, G., Quinn, S., Beatty, T., Penev, K., Johnson, M., Cargile, P., Latham, D., Bieryla, A., Collins, K., Dressing, C., Ciardi, D., Relles, H., Murawski, G., Nishiumi, T., Yonehara, A., Ishimaru, R., Yoshida, F., Gregorio, J., Lund, M., Stevens, D., Stassun, K., Scott Gaudi, B., Colón, K., Pepper, J., Narita, N., Awiphan, S., Chuanraksasat, P., Benni, P., Zambelli, R., Garrison, L., & Wilson, M. (2019). KELT-24b: A 5MJ Planet on a 5.6day Well-aligned Orbit around the Young V = 8.3 F-star HD 93148. Astronomical Journal, 158 (5) https://doi.org/10.3847/1538-3881/ab4136