Yale Researchers Unveil the Mystery of Double Hot Jupiters: A Dance of Gravity in Binary Star Systems

In a recent breakthrough, astronomers have uncovered the intriguing origins of the universe's most peculiar planets, known as "double hot Jupiters." These exoplanets are scorching hot gas giants that orbit so closely to their parent stars that a single year on their surface can last less than an Earth day. While hot Jupiters are rare, with only 1% of stars hosting one, even rarer are "double hot Jupiters" found in binary star systems with one planet orbiting around each of the twin stars. The discovery of these double hot Jupiters challenges existing theories of planet formation, and a team of astronomers at Yale University believes they may have found the key to this puzzle. Their research suggests that the normal, long-term evolution of binary systems can naturally lead to the formation of a hot Jupiter around each star. This process is known as von Zeipel-Lidov-Kozai (ZLK) migration, which posits that over time, planets with unusual orbits or orbital angles can be influenced by the gravity of another object, leading them to become a hot Jupiter close to their parent star. "The ZLK mechanism is a dance of sorts," explains team leader Malena Rice. "In a binary system, the extra star can shape and warp planets' orbits, causing the planets to migrate inward. We show how planets in binary systems can undergo a mirrored migration process, so that both stars end up with hot Jupiters." To reach their conclusion, Rice and colleagues performed a number of simulations of the evolution of binary stars with two planets using the Grace computing cluster at the Yale Center for Research Computing with data from NASA's Exoplanet Archive and the European Space Agency's (ESA) star-tracking mission Gaia. The results suggest that the right combination of separation between the stars is crucial for the formation of double hot Jupiters. "Our proposed mechanism works best when the stars are at a moderate separation," explains team member Tiger Lu. "They need to be far enough apart that giant planets are still expected to form around each star, but close enough together for the two stars to influence each other during the system lifetime." The team's research was published on June 10 in The Astrophysical Journal and has the potential to revolutionize our understanding of planet formation. The discovery not only sheds light on the origins of these rare exoplanets but also opens up new avenues for finding more double hot Jupiters by revisiting binary systems in which one hot Jupiter has already been discovered. In conclusion, this groundbreaking research by Yale University's team challenges existing theories and offers a new perspective on how planets form in binary star systems. As we continue to explore the cosmos, we may uncover even more mysteries about our universe's most curious planets.