| A potential asteroid bombardment in TRAPPIST-1 system |
| Zoltán Dencs |
| Konkoly Observatory, CSFK, Hungary |
| Three of the seven rocky planets in TRAPPIST-1 system orbit in the habitable zone of the host star. It means that water can be in liquid state at their surface, which is essential for life. Recent studies suggest that TRAPPIST-1 planets formed beyond the snow line of the host star, and collected significant amount of water in this region. However, a part of the initial water reservoir can be lost during the planet formation due to the stellar activity of an infant low-mass star. A potential subsequent water delivery could be provided by an asteroid bombardment event, similarly to the late heavy bombardment (LHB) in the Solar System. According to some theories a water delivery event can replenish the lost planetary water reservoirs. To study this water delivery process the 3DNAL group set up a simple model in which an additional planet is orbiting beyond the snow line of TRAPPIST-1. This putative eighth planet is embedded in a water-rich asteroid belt. Asteroids perturbed out from the chaotic zone of the putative planet can enter into the inner system and accreted by the known planets. I will show the details of our main findings, as well as the larger is the orbital distance of a given planet, the higher is the amount of water delivered to the planet by the LHB-like event. Moreover we found a short heavy and a longer lighter phase of the asteroid bombardment, depending on the initial position of the perturbed asteroids. |