A-type Stars, the Destroyers of Worlds: The lives and deaths of Jupiters in evolving stellar binaries

TL;DR

This paper studies how stellar companions influence the evolution and fate of gas giant planets around A-type stars, revealing the formation of temporary Hot Jupiters and the high likelihood of planetary destruction.

Contribution

It introduces the concept of Temporary Hot Jupiters formed during post-main sequence evolution and quantifies the impact of stellar companions on planetary survival.

Findings

Only 0.15% of A-type stars host Hot Jupiters during main sequence.

Approximately 3.7% of stars develop Temporary Hot Jupiters post-main sequence.

About 70% of gas giants around A-type stars are eventually destroyed or engulfed.

Abstract

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 ($1.6-2.4$ $M_\odot$, i.e., A-type main sequence stars) and evolved stars. The majority of A-type main sequence stars have stellar binary companions, which 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 (EKL) 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 lifetime. 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.