Recently, the Stellar Astrophysics Group at Yunnan Observatories, Chinese Academy of Sciences, has made significant progress in the study of stellar-planet tidal interactions. This research, led by Dr.GUO Shuaishuai under the guidance of Professor GUO Jianheng , has been published in the journal "Research in Astronomy and Astrophysics" (RAA). The study utilized a tidal interaction model established on Modules for Experiments in Stellar Astrophysics(MESA) to simulate a larger parameter space and discussed the influence of different initial parameters of hot Jupiters on stellar rotation. The results of this research can lead to refinements in the stellar rotation periods of hot Jupiter systems, thereby enabling more accurate stellar age estimation through gyrochronology.

The tidal interaction between close-in hot Jupiters and their host stars is of paramount importance. On the one hand, the tidal action of hot Jupiters on their host stars can accelerate the stellar rotation. On the other hand, tidal interactions cause the orbital decay of hot Jupiters, leading them to migrate towards their host stars.

The authors constructed a database of star-planet interaction models spanning 0.8 to 1.3 times the mass of the Sun for stars and 0.1 to 13.0 times the mass of Jupiter for planets. They also considered different stellar metallicities, initial orbital distances, initial stellar rotation periods, and tidal quality factors. Through analysis of the model database, it was found that for lower-mass stars with higher metallicities, the variation in stellar rotation period caused by planet engulfment quickly disappears after the planet is engulfed. Conversely, for higher-mass stars with lower metallicities, larger initial rotation periods and planetary masses result in more pronounced period changes, and the effects of planet engulfment persist for a longer duration.

Furthermore, Regarding the simulation results for the WASP-19 system, the influence of different initial stellar rotation periods on system evolution is minimal. The authors estimated the tidal quality parameter and initial semi-major axis of the system. In extreme cases, the use of gyrochronology could lead to an age estimate of WASP-19 exceeding 10 billion years, while its actual age is less than 220 million years. This discrepancy might erroneously portray an extremely old star as very young. Therefore, caution is advised when using gyrochronology for close-in hot Jupiter systems.

This achievement received support from the Chinese Academy of Sciences Strategic Priority Research Program, the National Key Research and Development Program, and the National Natural Science Foundation of China.

Contact：
Shuai-Shuai Guo
Yunnan Observatories, Chinese Academy of Sciences
Phone: 15600616369
E-mail: guoshuaishuai@ynao.ac.cn