Document Type


Publication Date


Published In

Astronomical Journal


We announce the discovery of KELT-23Ab, a hot Jupiter transiting the relatively bright (V = 10.3) star BD+66 911 (TYC 4187-996-1), and characterize the system using follow-up photometry and spectroscopy. A global fit to the system yields host-star properties of Teff = 5900 ± 49 K, M* = 0.945 ((+0.060)/(-0.054))M, R* = 0.995 ± 0.015 R, L* = 1.082 ((+0.051)/(-0.048)) L, log g* = 4.418 ((+0.026)/(-0.025) (cgs), and [Fe/H] = -0.105 ± 0.077. KELT-23Ab is a hot Jupiter with a mass of Mp = 0.938 ((+0.045)/-0.042)) M3, radius of Rp = 1.322 ± 0.025 R3, and density of ��P = 0.054 ((+0.038)/(-0.035)) g cm−3. Intense insolation flux from the star has likely caused KELT-23Ab to become inflated. The time of inferior conjunction is T0 = 2458149.40766 ± 0.00091 BJDTDB and the orbital period is P = 2.255353 ((+0.000031)/(-0.000030)) days. There is strong evidence that KELT-23A is a member of a long-period binary star system with a less luminous companion, and due to tidal interactions, the planet is likely to spiral into its host within roughly a gigayear. This system has one of the highest positive ecliptic latitudes of all transiting planet hosts known to date, placing it near the Transiting Planet Survey Satellite and James Webb Space Telescope continuous viewing zones. Thus we expect it to be an excellent candidate for long-term monitoring and follow up with these facilities.


This work is a preprint that is freely available courtesy of IOP Publishing and the American Astronomical Society. The final published version is available online.