Oral Presentation Astronomical Society of Australia Annual Scientific Meeting including HWWS 2013

Unveiling the 2D Chemistry of Protoplanetary Discs (#11)

Francesco Pignatale 1 , Sarah Maddison 1 , Kurt Liffman 2 , Geoffrey Brooks 3
  1. Swinburne University of Technology, Hawthorn, Vic, Australia
  2. MSE, CSIRO, Melbourne, Vic, Australia
  3. FEIS, Swinburne University of Technology, Melbourne, Vic, Australia

Planets, meteorites and all the objects of our Solar System result from different physical and chemical processes which occurred during the protoplanetary disc phase. IR observations of protoplanetary discs provide insights into the chemistry of the surface layers, but do not provide any information on the chemistry of the disc interior and the midplane where planets form. Theoretical radial condensation sequences are in general agreement with the bulk composition of the Solar System planets, but they can not explain the chemistry of rare objects like carbonaceous and enstatite chondrites, and the carbon-rich content of asteroids. Hence, more detailed modeling is required.

We utilize a chemical equilibrium code and a 2D disc model to derive the largest chemical simulation of the Solar Nebula, and, for the first time, simultaneously compute the chemical composition within all regions of the disc, from its surface to the midplane, for over 400 gases and solid compounds.

In this talk I will present an overview of the resulting 2D chemical distribution, focusing on some key compounds such as silicates, and show that: (1) the chemistry derived from IR observations are not representative of the bulk chemistry of the disc midplane; (2) we have identified the potential zone in which enstatite chondrites could have formed, supporting recent evidence that these objects and the surface of Mercury shared similar bulk compositions ; and (3) the 2D disc hosts carbon-rich reservoirs, which could have led to the formation of carbon-rich asteroids, and from which the gas giants might have accreted their atmospheres.

These new results were only achievable with the 2D chemical distribution, which provides new insight not possible with 1D condensation sequences.