Final Report Summary - DISCSIM (Hydrodynamical simulations of protoplanetary discs in the era of ALMA imaging)
The DISCSIM project has centred on theoretical/numerical modeling of protoplanetary discs in order to interpret new observational data on these objects, particularly that provided by the Atacama Large Millimetre Array (ALMA) which has evolved to full capacity over the timeline of the project. Our chief results relate to
i) the evolution of discs during their earliest, self-gravitating phase
ii) the study of disc dispersal due to external photoevaporation
iii) developing diagnostics of the presence of planets in discs and
iv) the modeling of chemical transport in discs.
In each area our theoretical work has been closely linked to the interpretation of observations and the acquisition and analysis of new observational data with which to test predictions. Under i) we have studied the conditions for fragmentation of self-gravitating discs and explained how disc mass affects the existence of a steady state with angular momentum transport dominated by spiral modes. We have modeled two striking recent examples of discs which show spiral structure consistent with gravitational instability. We have also examined the kinetics of dust in self-gravitating discs and have concluded that the collision speed between grains is sufficiently small so as to allow icy grains to undergo coagulation at this early evolutionary phase. Under ii) we have developed the first photochemical/hydrodynamical models for photoevaporation of discs by environmental ultraviolet radiation, and have shown that this is the dominant environmental effect in all star forming regions, far surpassing the effects of star-disc interactions in importance. We have also identified examples of photoevaporating discs in regions not previously known to experience this effect. Under iii) we have developed methods to interpret structure in mm and infrared continuum imaging of discs in terms of embedded planets. These studies allow the locations and masses of planets to be derived from imaging data; we have additionally shown how multi-wavelength data can be used to detect migration of protoplanets, a key process in the evolution of exoplanetary systems but one for which there is currently no direct observational evidence. We have acquired and analysed data on a remarkable four planet system orbiting a million year old star, providing the first evidence that the association between hot Jupiters and siblings at larger radii is in place already in the protoplanetary disc phase. Under iv) we have pioneered studies of radial transport of chemical species in discs. Our chemo-hydrodynamical modelling has been applied to the creation of solid cores within planets formed by gravitational instability as well as to the long range advection of species in the form of icy grain mantles. These studies pave the way for the future use of exoplanetary abundance data to constrain the location and mechanism for planet formation.
i) the evolution of discs during their earliest, self-gravitating phase
ii) the study of disc dispersal due to external photoevaporation
iii) developing diagnostics of the presence of planets in discs and
iv) the modeling of chemical transport in discs.
In each area our theoretical work has been closely linked to the interpretation of observations and the acquisition and analysis of new observational data with which to test predictions. Under i) we have studied the conditions for fragmentation of self-gravitating discs and explained how disc mass affects the existence of a steady state with angular momentum transport dominated by spiral modes. We have modeled two striking recent examples of discs which show spiral structure consistent with gravitational instability. We have also examined the kinetics of dust in self-gravitating discs and have concluded that the collision speed between grains is sufficiently small so as to allow icy grains to undergo coagulation at this early evolutionary phase. Under ii) we have developed the first photochemical/hydrodynamical models for photoevaporation of discs by environmental ultraviolet radiation, and have shown that this is the dominant environmental effect in all star forming regions, far surpassing the effects of star-disc interactions in importance. We have also identified examples of photoevaporating discs in regions not previously known to experience this effect. Under iii) we have developed methods to interpret structure in mm and infrared continuum imaging of discs in terms of embedded planets. These studies allow the locations and masses of planets to be derived from imaging data; we have additionally shown how multi-wavelength data can be used to detect migration of protoplanets, a key process in the evolution of exoplanetary systems but one for which there is currently no direct observational evidence. We have acquired and analysed data on a remarkable four planet system orbiting a million year old star, providing the first evidence that the association between hot Jupiters and siblings at larger radii is in place already in the protoplanetary disc phase. Under iv) we have pioneered studies of radial transport of chemical species in discs. Our chemo-hydrodynamical modelling has been applied to the creation of solid cores within planets formed by gravitational instability as well as to the long range advection of species in the form of icy grain mantles. These studies pave the way for the future use of exoplanetary abundance data to constrain the location and mechanism for planet formation.