KELT-4Ab: an Inflated hot Jupiter in a Hierarchical Trinary System

KELT-4Ab: An inflated Hot Jupiter transiting the bright (V~10) component of a hierarchical triple

Authors:

Eastman et al

Abstract:

We report the discovery of KELT-4Ab, an inflated, transiting Hot Jupiter orbiting the brightest component of a hierarchical triple stellar system. The host star is an F star with Teff=6206±75 K, logg=4.108±0.014, [Fe/H]=−0.116+0.065−0.069, M∗=1.201+0.067−0.061 M⊙, and R∗=1.610+0.078−0.068 R⊙. The best-fit linear ephemeris is BJDTDB=2456193.29157±0.00021+E(2.9895936±0.0000048). With a magnitude of V∼10, a planetary radius of 1.699+0.046−0.045 RJ, and a mass of 0.902+0.060−0.059 MJ, it is the brightest host among the population of inflated Hot Jupiters (RP>1.5RJ), making it a valuable discovery for probing the nature of inflated planets. In addition, its existence within a hierarchical triple and its proximity to Earth (210 pc) provides a unique opportunity for dynamical studies with continued monitoring with high resolution imaging and precision radial velocities. In particular, the motion of the binary stars around each other and of both stars around the primary star relative to the measured epoch in this work should be detectable when it rises in October 2015.