2018AJ....156..128S

Hot Jupiters (HJs), gas giant planets orbiting their host stars with periods on the order of days, commonly occur in the Galaxy, including relatively massive (1.6-2.4 M_☉, i.e., A-type main-sequence stars) and evolved stars. The majority of A-type main-sequence stars have stellar binary companions, that can strongly affect the dynamical evolution of planets around either star. In this work, we investigate the effects of gravitational perturbations by a far away stellar companion on the orbital evolution of gas giant planets orbiting A-type stars, the so-called Eccentric Kozai-Lidov mechanism, including the effects of general relativity, post-main-sequence stellar evolution, and tides. We find that only 0.15% of A-type stars will host HJs during their main-sequence lifetimes. However, we also find a new class of planets, Temporary Hot Jupiters (THJs), that form during the post-main-sequence lifetime of about 3.7% of former A-type main-sequence stars. These THJs orbit on periods of tens to a hundred days and only exist for a few 100,000 years before they are engulfed, but they reach similar temperatures as "classical" HJs due to the increased stellar luminosities. THJs' spin-orbit angles will mostly be misaligned. THJ effects on the host stars' evolution could also be observable for longer than a few 100,000 years. Overall, we find that approximately 70% of all gas giant planets orbiting A-type stars will eventually be destroyed or engulfed by their star, about 25% during the main-sequence lifetime, about 45% during post-main-sequence evolution.