Recently, the international journal Monthly Notices of the Royal Astronomical Society published research findings by Ph.D. candidate GUO Shuaishuai from the Stellar Physics Research Group at the Yunnan Observatories, Chinese Academy of Sciences, his supervisor Researcher GUO Jianheng, and other collaborators. The study focuses on the phase in the evolution of hot Jupiters around stars where a long-term synchronization phenomenon occurs between the stellar rotation rate and the planetary orbital rate.

Astronomers have discovered extremely massive hot Jupiters and brown dwarfs near certain types of stars. The presence of synchronized orbits can significantly slow down the tidal evolution of planetary systems and extend the lifespan of planets. Observational evidence suggests that close companions around F-type stars may have larger masses than those around lower-mass host stars. This is consistent with theoretical simulations.

The researchers combined stellar evolution with tidal interactions in star-planet systems. They found that when massive close-in planets orbiting stars larger than the Sun or with lower metallicity rotate around their host stars, the occurrence of double synchronization is more likely. Double synchronization occurs when the stellar rotation rate synchronizes with the planetary orbital rate.

The study examined a sample of 243 hot Jupiters and brown dwarf systems with relatively complete observational parameters orbiting F and G-type stars. The results indicates that the CoRoT-3 system may currently be in a state of long-term double synchronization, while the HAT-P-57 and KELT-21 systems may reach this state in the future as they evolve. This work has provided theoretical constraints for identifying observational samples that are in a state of double synchronization.

This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Key Research and Development Program, the National Natural Science Foundation of China, the Yunnan Talent Project, and the Key Laboratory for the Research of Supernovae in Yunnan Province.

Figure 1, the current evolutionary state of 243 observed systems. When a system is located above the solid line in the diagram, long-term double synchronization can be maintained. Image by GUO.