KELT-18b: Puffy Planet, Hot Host, Probably Perturbed Academic Article uri icon

abstract

  • Abstract We report the discovery of KELT-18b, a transiting hot Jupiter in a 2.87-day orbit around the bright (V=10.1), hot, F4V star BD+60 1538 (TYC 3865-1173-1). We present follow-up photometry, spectroscopy, and adaptive optics imaging that allow a detailed characterization of the system. Our preferred model fits yield a host stellar temperature of K and a mass of , situating it as one of only a handful of known transiting planets with hosts that are as hot, massive, and bright. The planet has a mass of m{J}}}$?> , a radius of m{J}}}$?> , and a density of m{g}},{mathrm{cm}}^{-3}$?> , making it one of the most inflated planets known around a hot star. We argue that KELT-18bs high temperature and low surface gravity, which yield an estimated 600km atmospheric scale height, combined with its hot, bright host, make it an excellent candidate for observations aimed at atmospheric characterization. We also present evidence for a bound stellar companion at a projected separation of 1100 au, and speculate that it may have contributed to the strong misalignment we suspect between KELT-18's spin axis and its planets orbital axis. The inferior conjunction time is 2457542.5249980.000416 (BJDTDB) and the orbital period is 2.87175100.0000029 days. We encourage RossiterMcLaughlin measurements in the near future to confirm the suspected spinorbit misalignment of this system.

published proceedings

  • ASTRONOMICAL JOURNAL

altmetric score

  • 82.28

author list (cited authors)

  • McLeod, K. K., Rodriguez, J. E., Oelkers, R. J., Collins, K. A., Bieryla, A., Fulton, B. J., ... Trueblood, P.

citation count

  • 12

publication date

  • June 2017