Orateur
Description
Large impacts dominated the accretion during the early solar system. They contribute to the
heating, melting, and sometimes vaporization of the impact bodies. Quantifying the frequency of
the different resulting structures’ aftershocks is a key point in understanding the evolution of the
protoplanetary disk. In this study, we work on the behavior of early Earth-like materials under
shocks.
We performed ab initio molecular dynamics simulations using the VASP6 package. The post-
processing analysis was done with the UMD package [1].
We compare the Hugoniot equations of the state of realistic multi-component silicate systems
under different shock conditions. We choose different compositions which are relevant for the
early stage of Earth’s accretion. We monitor changes in the Hugoniot equation of the melts when
the initial density and temperature of the shocked material change. However, changes in the
composition of the major elements do not affect the Hugoniot. The Hugoniot equation provides
realistic PT conditions that the bodies experience as a result of impacts during accretion. Using
thermodynamic integration methods we compute the entropy produced during a shock and the
liquid-vapor dome of the pyrolite in the entropy against temperature phase space. Those hugoniots
in the entropy-temperature diagram give us a precise criterion to estimate if an impact leads to
partial vaporization. Thanks to our results, we can build new scenarios about the physical states
of proto-planets and planetary bodies during the early stages of solar system formation. The
characterization of the physical state of the protoplanetary disk may have a significant impact on
our view of the early degassing of primordial reservoirs and volatile distribution in the early solar
system.
