Phyllosilicates as a source of water in the Trappist-1 protoplanetary disk

In many ways the architecture of the Trappist-1 system resembles that of the Galilean moons orbiting around Jupiter. With seven confirmed planet, including three terrestrial planets in the habitable zone, it is a unique laboratory to study planetary formation scenarios. Recent results derived from interior modelling show a gradient in the planets’ water mass fractions (WMF). From little to no water to an estimated WMF of 10%, this gradient is puzzling formation models considering that all planets’ orbits are inside the system’s snow line. A mean to bring water inside the snow line is to consider the dihydroxylation of hydrated minerals. Phyllosilicates are good candidates as they can carry up to 10% of water in mass. With a 1+1D proto- stellar nebula toy model (PSN), we study the effect of a water vapor source at the location of the dehydroxylation of particles dominated by phyllosilicates. One major unknown remains however the dehydroxylation temperature of phyllosilicates under PSN thermodynamic conditions. We have then used three plausible devolatilization temperatures, namely 400 K, 600 K and 800 K. We show that the water vapor released from phyllosilicates can increase the water ice abundance located at the snowline. Those enrichments range from 2 to 5 times the initial water abundance in phyllosilicates.