KELT-24b: A 5M _J Planet on a 5.6 day Well-aligned Orbit around the Young V = 8.3 F-star HD 93148

November 2019 • 2019AJ....158..197R

Authors • Rodriguez, Joseph E. • Eastman, Jason D. • Zhou, George • Quinn, Samuel N. • Beatty, Thomas G. • Penev, Kaloyan • Johnson, Marshall C. • Cargile, Phillip A. • Latham, David W. • Bieryla, Allyson • Collins, Karen A. • Dressing, Courtney D. • Ciardi, David R. • Relles, Howard M. • Murawski, Gabriel • Nishiumi, Taku • Yonehara, Atsunori • Ishimaru, Ryo • Yoshida, Fumi • Gregorio, Joao • Lund, Michael B. • Stevens, Daniel J. • Stassun, Keivan G. • Gaudi, B. Scott • Colón, Knicole D. • Pepper, Joshua • Narita, Norio • Awiphan, Supachai • Chuanraksasat, Pongpichit • Benni, Paul • Zambelli, Roberto • Garrison, Lehman H. • Wilson, Maurice L. • Cornachione, Matthew A. • Wang, Sharon X. • Labadie-Bartz, Jonathan • Rodríguez, Romy • Siverd, Robert J. • Yao, Xinyu • Bayliss, Daniel • Berlind, Perry • Calkins, Michael L. • Christiansen, Jessie L. • Cohen, David H. • Conti, Dennis M. • Curtis, Ivan A. • Depoy, D. L. • Esquerdo, Gilbert A. • Evans, Phil • Feliz, Dax • Fulton, Benjamin J. • Holoien, Thomas W. -S. • James, David J. • Jayasinghe, Tharindu • Jang-Condell, Hannah • Jensen, Eric L. N. • Johnson, John A. • Joner, Michael D. • Khakpash, Somayeh • Kielkopf, John F. • Kuhn, Rudolf B. • Manner, Mark • Marshall, Jennifer L. • McLeod, Kim K. • McCrady, Nate • Oberst, Thomas E. • Oelkers, Ryan J. • Penny, Matthew T. • Reed, Phillip A. • Sliski, David H. • Shappee, B. J. • Stephens, Denise C. • Stockdale, Chris • Tan, Thiam-Guan • Trueblood, Mark • Trueblood, Pat • Villanueva, Steven, Jr. • Wittenmyer, Robert A. • Wright, Jason T.

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.

Links

• PREPRINT http://arxiv.org/abs/1906.03276
• ELECTR https://doi.org/10.3847%2F1538-3881%2Fab4136
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2019AJ....158..197R
• PDF https://stacks.iop.org/1538-3881/158/197/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/158/197
• DATA http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?type=REFERENCE&bibcode=2019AJ....158..197R