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COALA - Computational Astrophysics Laboratory

Planetary Science

Raquel Salmeron

Planet and Star Formation

The mechanism(s) responsible for generating the angular momentum transport required for star/planet formation remain poorly understood. A number of mechanisms have been invoked over the years (e.g., Stone et al. 2000), but they have all proved to be either extremely inefficient (molecular viscosity), not general enough (the presence of a companion star) or not to work at all (convection). In recent times it has been realised that the answer may lie in the complex interaction of gas and magnetic fields present in the flattened disc of material that surrounds the star in formation (e.g., Balbus & Hawley 1998) . Analytical and numerical studies conducted so far have adopted a number of simplifications to treat the fluid, but they are poor approximations to the gas in these cold, dense `protostellar discs'.

Magneto-Hydrodynamics (MHD) Simulations. Salmeron aims to use a novel theoretical model, incorporating (a) a realistic treatment of the microphysics, and (b) a more comprehensive range of physical mechanisms, to model protostellar disc dynamics and the fast jets that are commonly associated with them (Fig. 5.1). It will, specifically construct new, realistic models of the mechanisms responsible for angular momentum transport in a protoplanetary system, determine the resulting disc -- jet structure and examine the implications for planet formation and migration in such discs. This research project offers a fresh approach to these issues, based upon previous contributions Dr. Salmeron has made in the area of protostellar disc dynamics, particularly the modelling of magnetically-driven turbulence in accretion discs (Salmeron & Wardle 2003, 2004, 2005, 2008) and fundamental studies of the radial and vertical angular momentum transport in these systems (Salmeron et al. 2007a,b). These models are computationally intensive, particularly when a realistic ionization and thermal structure are incorporated in the calculations. COALA will be very useful for efficient testing and debugging of the code, as well as for the timely manipulation and analysis of the results.

Figure 5.1 - A Hubble Space Telescope image of a young, forming star and its associated jet. The mechanism that enables disk material to flow towards the centre to form the star -- and the impact on any forming planets -- remains poorly understood.

COALA : Universe Galaxy AGN Star Planet