14:45 〜 15:00
[PAE18-17] Constraints on early atmospheric evolution from the dynamical architecture of the TRAPPIST-1 system
キーワード：TRAPPIST-1, Atmospheric mass loss, Angular momentum transfer, N-body simulations, Orbital dynamics, Planetary resonances
The TRAPPIST-1 system, a remarkable seven-planet configuration located 40 light-years away, exhibits intricate mean motion resonances that suggest a stable yet complex dynamical history. The system's planets, likely once surrounded by hydrogen-dominated atmospheres, are believed to have experienced significant atmospheric escape during their early stages, primarily driven by photoevaporation. This process likely played a key role in shaping their current orbital properties and the system's long-term stability.
We aim to investigate the long-term evolution of the TRAPPIST-1 system with atmospheric mass loss. By exploring the impact of this atmospheric mass loss on orbital configurations, we aim to constrain the planets' initial atmospheric conditions.
We use N-body simulations to model the long-term evolution of the TRAPPIST-1 system, incorporating mass loss and orbital changes due to angular momentum transfer between escaped gas and the planet. These simulations allow us to track changes in the planets' orbits under different mass loss scenarios, testing various mass loss fractions and angular momentum transfer efficiency.
Our results show that even modest atmospheric mass loss can lead to significant changes in the orbital configuration of the TRAPPIST-1 planets. The figure shows the case where the innermost planet, TRAPPIST-1 b, loses about 1.8% of its initial mass with the mass loss timescale of 1 Myr under angular momentum conservation—that is, all the angular momentum of escaped gas is transferred to the planet. The orbit of the innermost planet expands, leading to convergent migration between the planets. The eccentricities of the planets increase and the 3-body resonance (3BR) angle of the b-c-d pair shifts to about 45°, indicating a significant change in the resonant relationship. This demonstrates that a mass loss fraction of around 2% can lead to noticeable changes in the system's orbital configuration.
We conclude that the TRAPPIST-1 planets likely retained no more than 6% of their primordial atmospheres during formation, offering new constraints on their early atmospheric evolution.
We aim to investigate the long-term evolution of the TRAPPIST-1 system with atmospheric mass loss. By exploring the impact of this atmospheric mass loss on orbital configurations, we aim to constrain the planets' initial atmospheric conditions.
We use N-body simulations to model the long-term evolution of the TRAPPIST-1 system, incorporating mass loss and orbital changes due to angular momentum transfer between escaped gas and the planet. These simulations allow us to track changes in the planets' orbits under different mass loss scenarios, testing various mass loss fractions and angular momentum transfer efficiency.
Our results show that even modest atmospheric mass loss can lead to significant changes in the orbital configuration of the TRAPPIST-1 planets. The figure shows the case where the innermost planet, TRAPPIST-1 b, loses about 1.8% of its initial mass with the mass loss timescale of 1 Myr under angular momentum conservation—that is, all the angular momentum of escaped gas is transferred to the planet. The orbit of the innermost planet expands, leading to convergent migration between the planets. The eccentricities of the planets increase and the 3-body resonance (3BR) angle of the b-c-d pair shifts to about 45°, indicating a significant change in the resonant relationship. This demonstrates that a mass loss fraction of around 2% can lead to noticeable changes in the system's orbital configuration.
We conclude that the TRAPPIST-1 planets likely retained no more than 6% of their primordial atmospheres during formation, offering new constraints on their early atmospheric evolution.