Friendless 'hot Jupiter' exoplanets may not be so lonely after all

"Precisely how hot and warm Jupiters evolved to their short-period orbits around their host stars has been an open question for over 25 years. One leading theory suggests that hot Jupiters formed far away from their host stars in highly elliptical orbits, which shrunk over time into tight, circular paths. During this process, the gas giants migrated toward their parent star. On the way, these giants which gravitationally interacted with other planets and virtually kicked them out of their star systems. This way, they soon became the solitary worlds seen today. A second, less quoted theory posits that hot Jupiters formed in the outer regions of the stellar disk but migrated inward in a more peaceful way, which allowed them to coexist with other nearby planetary companions. So far, astronomers have only found a handful of such systems to support this theory.
In the new study, Wang and his co-authors propose a "unified framework" that incorporates both theories. About 12% of those gas giants form in star systems along with other planets but do not experience strong gravitational interactions with their planetary neighbors, which would explain the handful of detected hot Jupiters with nearby companions, while the remaining 88% of the planets would strip their systems of other planets, supporting the observations from Kepler and TESS, according to the study. While scientists still do not fully understand how hot Jupiters migrate inward, the presence of neighbor worlds around them is strong evidence that not all hot Jupiters have a violent history as was previously thought, Wang said at the news briefing last week. The new research is described in a paper published in March in The Astronomical Journal."

My note. We are getting into the exoplanet weeds now :)