KELT-24b: A 5M J Planet on a 5.6 day Well-aligned Orbit around the Young V = 8.3 F-star HD 93148
Cargile, Phillip A.; Bieryla, Allyson; Latham, David W.; Quinn, Samuel N.; Berlind, Perry; Calkins, Michael L.; Esquerdo, Gilbert A.; Pepper, Joshua; Stassun, Keivan G.; Siverd, Robert J.; Zhou, George; Bayliss, Daniel; Tan, Thiam-Guan; Kuhn, Rudolf B.; Wittenmyer, Robert A.; Fulton, Benjamin J.; Wright, Jason T.; Collins, Karen A.; Holoien, Thomas W. -S.; Shappee, B. J.; Ciardi, David R.; Narita, Norio; Lund, Michael B.; Rodriguez, Joseph E.; Oelkers, Ryan J.; Stevens, Daniel J.; Beatty, Thomas G.; Gaudi, B. Scott; Labadie-Bartz, Jonathan; Penev, Kaloyan; Johnson, Marshall C.; Colón, Knicole D.; Evans, Phil; Yao, Xinyu; Stockdale, Chris; Eastman, Jason D.; Cohen, David H.; Curtis, Ivan A.; Feliz, Dax; Gregorio, Joao; Jensen, Eric L. N.; Johnson, John A.; Joner, Michael D.; Kielkopf, John F.; Manner, Mark; McCrady, Nate; McLeod, Kim K.; Oberst, Thomas E.; Penny, Matthew T.; Reed, Phillip A.; Sliski, David H.; Stephens, Denise C.; Villanueva, Steven, Jr.; Zambelli, Roberto; Relles, Howard M.; Dressing, Courtney D.; James, David J.; Yonehara, Atsunori; Christiansen, Jessie L.; Wang, Sharon X.; Conti, Dennis M.; Jang-Condell, Hannah; Murawski, Gabriel; Jayasinghe, Tharindu; Nishiumi, Taku; Awiphan, Supachai; Benni, Paul; Wilson, Maurice L.; Cornachione, Matthew A.; Yoshida, Fumi; Ishimaru, Ryo; Chuanraksasat, Pongpichit; Garrison, Lehman H.; Rodríguez, Romy; Depoy, D. L.; Khakpash, Somayeh; Marshall, Jennifer L.; Trueblood, Mark; Trueblood, Pat
United States, Poland, Japan, Portugal, Spain, Thailand, Italy, Brazil, United Kingdom, Australia, Chile, South Africa
Abstract
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 T eff = {6509}-49+50 K, a mass of M * = {1.460}-0.059+0.055 M ⊙, a radius of R * = 1.506 ± 0.022 R ⊙, 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 (λ ={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. 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.