1. Dynamics of Binary Planets within Star Clusters
- Author
-
Huang, Yukun, Zhu, Wei, and Kokubo, Eiichiro
- Subjects
Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Solar and Stellar Astrophysics - Abstract
We develop analytical tools and perform three-body simulations to investigate the orbital evolution and dynamical stability of binary planets within star clusters. Our analytical results show that the orbital stability of a planetary-mass binary against passing stars is mainly related to its orbital period. We find that critical flybys, defined as stellar encounters with energy kicks comparable to the binary binding energy, can efficiently produce a wide range of semimajor axes ($a$) and eccentricities ($e$) from a dominant population of primordially tight JuMBOs. Applying our results to the recently discovered Jupiter-Mass Binary Objects (JuMBOs) by the James Webb Space Telescope (JWST), our simulations suggest that to match the observed $\sim$9\% wide binary fraction, an initial semimajor axis of $a_0 = 10$--20~au and a density-weighted residence time of $\chi \gtrsim 10^4$~Myr~pc$^{-3}$ are favored. These results imply that the JWST JuMBOs probably formed as tight binaries near the cluster core., Comment: 9 pages, 4 figures, submitted to ApJL
- Published
- 2024