PRACE: Quantitative models of a star forming cluster

The PRACE project "Quantitative models of a star forming cluster" will be executed on the Marconi supercomputer for a one year period during 2016-2017. It has been granted 2.5 million core-hours on the x86 broadwell partition and 19.5 million core-hours on knights landing partition of Marconi. In this project page we are collecting and documenting the results from the project.
Project members:
Troels Haugbølle (PI), Søren Frimann, Troels Frostholm, Tommaso Grassi, Jes Jørgensen, Michael Küffmeier, Åke Nordlund, Paolo Padoan, Andrius Popovas, Neil Vaytet
Molecular clouds are made of supersonic, magnetized turbulent cold gas, where energy cascades from large to small scales, generating a roughly self-similar structure down to the gravitationally collapsing scale. This process is a multi-scale phenomenon, and couples the dynamics of molecular clouds at the tens of parsec scale to proto-planetary systems at the astronomical unit scale through the accretion history and magnetic field anchoring. The gravitational collapse channels gas through a disc to the star, in a delicate balance with the environment. Proto-planetary systems consist of dust and gas envelopes, centrifugally supported discs, and powerful outflows, all of which surround a newborn star. Molecules, ices and dust are being destroyed and reformed in a highly dynamical environment, where processes are driven by accretion and the proto-stellar radiation. The new sub-mm facility ALMA is currently providing the first detailed observations of inner discs where planets are harbored. Advanced modeling is crucially important to interpret and make best use of these observations. During the past year, we have built up expertise in complex chemistry, radiative transfer, and dust modeling, leading to the first quantitative models of star forming regions and proto-planetary systems embedded in global models that can be directly compared to ALMA data, and further our understanding of the intricate physics behind star and planet formation.

We propose to perform the first ever simulations of a forming cluster of stars in a Giant Molecular Cloud fragment that includes full non-equilibrium H-C-O chemistry and photochemistry. For the large-scale model we will use a simplified density-optical extinction relation, while re-simulations of single stellar objects will be done including ray-tracing radiative energy transfer. We propose to use 22 million core hours on Maconi which, because of several innovative and new techniques, is enough to 1) evolve a stellar cluster in an already existing model of a 40 parsec Giant Molecular Cloud fragment for an additional 500 kyr at 1 astronomical unit resolution where we expect roughly 1000 stars to form, and 2) zoom-in on selected protostars in the cluster for at least 10 kyr with 0.06 astronomical unit resolution and radiative transfer. This proposal goes far beyond what has been done until now, both by our own and competing groups, with a hitherto unrivalled realistic model of a protostellar cluster, including large-scale anchoring, non-equilibrium photochemistry, and extremely high spatial resolution.