Possible rewrite: Presence of companionship challenges the notion of ‘Hot Jupiters’ as solitary orbiters.

The research, led by an Indiana University astronomer, challenges long-held beliefs about isolated “hot Jupiters” and proposes a new mechanism for understanding the evolution of exoplanets.

While Jupiter is farther from the Sun, hot Jupiters are gas giant planets that orbit stars outside our solar system with an orbital period of less than 10 days. Previous studies indicated that they rarely have any nearby companion planets, leading scientists to believe that hot Jupiters formed and evolved through a violent process that kicked other planets out of the region as they approached their host stars. The research team’s findings reveal that hot Jupiters don’t always orbit on their own.

“Our research shows that at least a portion of hot Jupiters could not have formed through a violent process,” said Songuo Wang, assistant professor of astronomy in the College of Arts and Sciences. “This is an important contribution to further our understanding of the formation of hot Jupiters, which can help us learn more about our solar system.”

The study has been published in The Astronomical JournalWang presented the search results in June 2023 meeting of the American Astronomical Society In Albuquerque, New Mexico.

The researchers analyzed the full four-year dataset of warm, hot Jupiter from NASA’s Kepler mission. Warm Jupiters have a longer orbital period, ranging from 10 to 300 days. The researchers used transit timing differences to determine that at least 12% of hot Jupiters and 70% of warm Jupiters have a close companion planet orbiting their host stars.

Wang and his collaborators combined their findings with existing observational limitations to propose a new framework to explain the evolution of hot, warm Jupiters and why some have companion planets. They determined that the formation of hot and warm Jupiter systems depends on the presence of gas giants in the system, which affects how well the planets interact and migrate.

The findings provide a starting point for future research on exoplanets and planets in our solar system.

“The ultimate goal for astronomers is to put our solar system in the bigger picture — are we unique?” Wang said. “This helps us understand why there are no hot Jupiters in our solar system.”

Additional collaborators are Dong-Hong Wu, a lecturer in the Department of Physics at Anhui Normal University, and Malena Rice, a 51 Pegasi b fellow at MIT and upcoming professor at Yale.

Wang has always been interested in the formations and demographics of the outer planets. It uses observational research to try to understand their dynamics and origins, helping astronomers better understand how our solar system fits into a larger cosmic context.