SEMINAR OF THE DEPARTMENT OF ASTRONOMY
Volatile loss from the Moon driven by Earth's tides
a talk by Gustavo Madeira (Observatório Nacional)
Abstract:
The similarities in the mass-independent isotopic composition of refractory elements between the Moon and the bulk silicate Earth suggest that both bodies formed from the same reservoir of material. On the other hand, the volatile depletion of the Moon and the isotopic composition of moderately volatile elements point to a global devolatilisation process, likely during a lunar magma ocean phase. We investigate the devolatilisation of a molten Moon due to tidally-assisted hydrodynamic escape, with a focus on the dynamics of the evaporated gas. Unlike the steady-state 1D approach of Charnoz et al. (2021), we use time-dependent 2D hydrodynamic simulations to account for the magma ocean as a source of gas. Near Earth's Roche limit, where the proto-Moon likely formed, gases evaporated from the lunar magma ocean form a circumterrestrial volatile disk, with less than 30% of the material being reaccreted by the Moon. We find that the measured depletion of K and Na on the Moon can be reproduced if the lunar magma ocean has a surface temperature of approximately 1800–2000 K. After about 1000 years, a thermal boundary layer or flotation crust forms a lid that inhibits further volatile escape. Mapping the volatile velocity field reveals varied trends in volatile reaccretion longitudes on the lunar surface: material is predominantly reaccreted on the farside once the Earth–Moon distance exceeds 3.5 Earth radii, suggesting a dichotomy in volatile abundances between the nearside and farside of the Moon. This dichotomy may provide insights into the tidal conditions of the early molten Earth.
Short-Bio:
Gustavo holds a Bachelor's degree in Physics from the São Paulo State University (UNESP), where he also completed his Master's and PhD in Physics and Astronomy. He was a postdoctoral researcher at the Institut de Physique du Globe de Paris for two years and is currently an adjunct researcher in Planetary Science at the National Observatory of Brazil. He is the founder of the Satellite Origin and Dynamics Group (GODS), a former member of NASA's DART mission, and is currently part of ESA’s Hera mission. His research aims to advance our understanding of the formation, evolution, and composition of bodies in the Solar System, as well as those in exoplanetary systems.
Google Meet: https://meet.google.com/pcw-gmem-jyi
Link da transmissão: https://www.youtube.com/c/AstronomiaIAGUSP/live