Modeling Oxygen Isotopes in the Nascent Solar Nebula for Material to be measured with Rosetta at Comet 67P/Churyumov-Gerasimenko

Abstract:

There are various propositions to explain the formation of the Solar System, yet the information we have about the processes in the proto-Sun is not sufficient to explain its evolution. Studies on chondritic meteorites have shown that they have been formed in the early stages of Solar system growth. Similarly, comets that are mixtures of frozen volatiles and nonvolatile dust carry contents that can provide information about the dynamic processes in the nascent solar nebula. Oxygen is the third most abundant element in the Solar System, and its isotope variability shows indications of a wide range of phenomena such as CO self-shielding and secondary nucleosynthesis. The study of Oxygen isotopes in the nascent solar nebula itself enlightens some of the aforementioned processes as well as magnetic properties of the proto-Sun. Rosetta, an ESA cornerstone mission with a NASA contribution, is on its way to visit comet 67P/Churyumov-Gerasimenko in 2014. Instruments on board will sample the ¹⁶O, ¹⁷O, ¹⁸O content of this primitive body.

In this paper, we would like to address the potential for creation of reservoirs for the stable isotopes of oxygen, and their water isotopologues, including the imposition of radial excursions of proto-coronal flow on the inner edge of the proto-solar disc. The University of Michigan Adaptive Mesh Particle Simulator (AMPS) code is used in this study. The AMPS code employs the Direct Simulation Monte Carlo method to solve Boltzmann Equation for probabilistic distributions of particles in rarefied gas flows. The magnetic and electric field structures are embedded in the model. The magnetic field is a scalar bipolar field, which is characterized by negative polarity surrounded by positive polarity that is similar to that of Coronal Bright Points observed in the Sun. Prelminary results from the study include oxygen formation via collisions, and other processes, in preparation for isotope fractionation work in future steps.

This project was supported at the Jet Propulsion Laboratory/California Institute of Technology under a contract with NASA.